June 1, 2017 • 51 mins
In this episode of The Psychology Podcast, Dr. Eric Turkheimer and I take a deep dive into some of the most complex and controversial topics in all of psychology. What is intelligence? How is intelligence measured? Is intelligence meaningful? Is IQ modifiable? Is IQ heritable? What does heritability really mean? Is heritability of IQ the same across social classes? Are there race differences in IQ? If so, what are the potential causes of race differences in IQ? Why does any of this matter? Note to our listeners: This is a very technical discussion, mostly geared towards those who are interested in understanding the debate, and the various nuances on the table. For those who would like to join in the discussion, you can do so below. Enjoy!
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Episode Transcript
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Speaker 1 (00:00):
Hello, and welcome to the Psychology Podcast with Doctor Scott
Barry Kaufman, where we give you insights into the mind, brain, behavior,
and creativity. Each episode will feature a new guest who
will stimulate your mind and give you a greater understanding
of yourself, others, and the world we live in. Hopefully
we'll also provide a glimpse into human possibility. Thanks for
listening and enjoy the podcast. So today it's great to
(00:40):
have doctor Eric Turkheimer on the podcast. Doctor Turkhimer is
the Hugh Scott Hamilton Professor of Psychology at the University
of Virginia. His lab studies how interactions between genes and
environments shape the development of human behavior. Today, we'll be
focusing mostly on Turkimer's research on intelligence, genetics, and family background.
The topic of intelligence is a favorite here the Psychology Podcast.
(01:01):
Some of our previous guests discussing this topic include Christopher
Shaburri and Stuart Ritchie. I personally have studied this topic
since the beginning of my career, so I'm always eager
to engage in respectful, mature discussion on the topic. If
you'd like to join in the discussion, please go to
the Psychology podcast dot com and leave comments on the
post for this episode. Eric. Great to have you on
(01:21):
the show today. Nice see us, Scott. Let's jump right
into this. What is intelligence? How do you define it?
What's your personal conceptualization? I think intelligence is the ability
to process information and solve problems. I mean, that's pretty basic,
(01:42):
I guess. I mean there's more technical definition of intelligence,
of course, but I don't know. I guess I think
that's a pretty good starting place, Okay. And then there's
so there's two issues of the question of a definition,
and there's the issue of measurement. Now what do you
think are some of the best measures of what you
just defined that are out there right now? Well, I
(02:05):
don't know. I don't know what you mean specifically. But
there's of course an entire universe of intelligence tests IQ
tests so called, of various different kinds, and those range
from formal IQ tests that you might take with a
professional psychologist too. In my opinion, things like the SATs
(02:28):
that you take in high school are more or less
a kind of intelligence test. They're formulated and conceptualized a
little bit differently. So it sounds like you're saying IQ
test that's the answer, it sounds like you're saying because
one could say that it's you know that IQ is
a very limited measure of intelligence, and there's been arguments
in that effect and et cetera. So I just want
(02:50):
to make sure that we're on the same page, that
everyone understands exactly what you're saying at every step of
this way. Yeah, and I think if this is where
you're headed, that some of the more general things that
people sometimes talk about as intelligence, social intelligence, and in
our personal intelligence and emotional intelligence, those are all really
important things in the world. But I guess I do
(03:13):
think of those as separate from what I think of
as intelligence per se, which is more about problem solving
specifically than it is about the kind of much broader
activities that people have to conduct in the world. Yeah. Sure,
but you know, so one could make the argument that
(03:34):
certain kinds of problem solving are very contextual, based on
the mean specific areas of human adaptation throughout the course
of human evolution. So it sounds like when you say
problem solving, you talk about a general problem solving ability
that's captured by what we can talk about the G factor.
We can talk about the chief factor if you want yeah,
we should talk about the G factor because I have
(03:55):
fairly particular ideas about the G factor that may aren't
necessarily the same as other people you might talk to
about it. Great, I'd love to hear what your thoughts
are on the G factor, and you can understand why
I want to make sure we qualify how you think
about intelligence and how you think we should measure it,
because you know there is no objective, you know ten
(04:17):
commandments that God gave us saying this is the measure
of intelligence, and this is how we should defind So
you know, that's why it's very important for people to
quarify their terms. So tell me what the G factor is? Well,
I mean, what the G factor definitely is? I mean,
and I think the question is whether it's more than this,
But what it I think it indisputably is. Is a
(04:41):
statistical construct that describes the fact that ability tests, very broadly,
ability tests are positively correlated with each other, and people
who do well on one ability tests tend to do
well on other ability tests. People often speak as though
the positive of correlations among ability tests mean that there
(05:03):
is only one kind of intelligence that explains all of
why tests go together and I don't think that's the case,
even though it's the case that the correlations among different
ability tests are positive. But in any event, as a
statistical matter, anytime you have a number of tests that
are positively correlated with each other, it's possible in a
(05:26):
statistical way to extract from that matrix of tests something
that's called the first principal component, which describes the way
that those tests correlate together. And that literally is what
general intelligence or G is. It's the first principal component
(05:47):
of a matrix of positively correlated intelligence tests. Now, at
that point, I think there comes a theoretical fork in
the road in the history of thinking about intelligence. That
one school of thought about intelligence, and I think probably
it's safe to say the dominant school of thought about
(06:09):
intelligence that goes back to Charles Spearman, says that this G,
this statistical G thing that describes the positive correlation among
a whole bunch of ability tests, must represent some kind
of actual thing inside human beings that causes those tests
(06:29):
to go together, something in our brain that represents G,
something in our genes that represent G. I don't agree
with that conclusion. I think it's much better to think
of G as a descriptive thing rather than a causal thing.
G is a way of describing the way mental tests
(06:50):
go together. It's not a way of explaining why mental
tests go together. Beautiful. That is in line with a
lot of recent research on statistical modeling of G showing
that it's a better model to look at G as
reflective variable, you know, in a structural equation model, as
sort of the emergent property of multiple indicators of cognobility
(07:10):
as opposed to the causal force. So even from like
a from a statistical model and then from a brain
model theory kind of oh, you know, I'm referring to
recent statistical models of G that have tried to model
it as either a causal force or an outcome, you know,
and research shows that it does make more sense to
think of it, you said, descriptive, and that's exactly what
(07:31):
the research suggests, is a better way of things as
an emergence. You know, it's not a thing, it's an
emergent property. And also it's that seems in line with
the recent research on G not making any sense as
existing in an individual brain. It has to do with
individual differences, you know. Even Arthur Jensen, who a lot
of people malign or you know, who's done a lot
(07:52):
of good scientific work on this topic. And we can
get to some of his more controversial stuff later, but
he has done some significant scientific work. You know. He
made the case that G intelligence has no meaning if
you're the only one in a desert island, if you
can't compare your G leveled anyone else in that island,
it makes no sense to you can't measure your G.
So all that I just want to say is consistent
(08:13):
with what you just said. Yeah, and I think to
get back, I think I've placed a marker on something
while we're getting to where we are about the uni
dimensionality of G and intelligence, because I think that's very
important that, you know, going back to Charles Spearman, who
came up with this idea in the first place. People
have asked, once again a statistical question about whether all
(08:34):
of the various covariation along the many the infinite number
of mental tests that you could give to people can
be fit by a single common factor. And the answer
to that question, going back to Spearman, is no. In fact,
as domains of tests go, it's true that intelligence is
fairly well fairly well described by a single factor, more
(08:58):
than say personality or something thing. But Spearman himself showed
that G per se, one single factor was not enough.
And I think, people, well, it's two things. People. It
can be very easy to think that because all tests
are positively correlated with each other, that means that there
(09:19):
must only be one thing that's causing them, and that,
as a statistical matter, is not the case. And second,
once you come up with this statistical thing called G
and describe it mathematically and name it as G, it's
very easy to fall in love with it a little
bit and think that, well, now that we have this
(09:39):
thing called G, and it does describe quite a bit
of the variation and intelligence, that it must be the single,
one and only thing and the whole domain of describing
something as complicated as intelligence with latent factors like G,
it's way more complicated as soon as you have more
(09:59):
than one factor to work with. Great points, And I
really like the Johnson and Bichard model that has really
done some systematic analyses of the fundamental group factors of
G and shown in verbal, nonverbal, and spatial are some
pretty essential group factors. Yeah, so you one can reduce
all these different cognitive ability tests to a single dimension,
(10:20):
and one can do that and that does have predictive value.
Something my mentor Nickel I did my master's agree with
Nicholas McIntosh at Cambridge, who I think wrote the best
textbook on this topic. And you know, he constantly has
made that point that you know, G, this positive manifold
doesn't stop with cognitobility. There are a whole nexus of
(10:42):
socioeconomic status. I mean, this normalogical network of G is
very broad. And one thing that is difficult to do
is disentangle, you know, all of these causal forces and
disentangle which is causing what you know within this normalogical network,
because that it's no easy feed, is it. No? That's right, yeah.
(11:04):
And one school of thought that I'm sure we'll get
into is to sort of take G and put it
at the center of that universe and say that everything
else that happened is caused by this G thing, rather
than seeing G as part of a much broader descriptive network. Good.
(11:25):
And you know, one analogy that I've been kicking around
some is with the idea of health. Let's say you
took a whole bunch of medical measurements from people. You
got their blood pressure and their BMI and their lung
capacity and how fast they could run, and all those
various things, and got correlations among all those things. They
(11:48):
would be I would imagine positively correlated. Maybe not quite
as positively correlated as mental tests are, but you'd still
be able to take a first principal component out of
them that describe the way all these various health measures
go together, and you can call it health. And some
people at any given moment are healthier than other people.
(12:09):
We're very accustomed to talking about it this way, and
on surveys you ask people a single question, you know,
how good would you how would you describe your health
on a scale from one to ten. But it wouldn't
occur to us to think of health as this special
inner quality that people carry around, And it wouldn't occur
to us to start looking for the health center in
(12:32):
people's brain body, or start to ask, well, what are
the specific genes that cause people to be healthier than
each other. We recognize health as just what you say.
It's a health is a way of describing a certain
domain of covariation in a very complicated network of things.
(12:54):
But it's not a cause of those things, it's a
description of those things. I love that. And then it
also taking that analogy, it seems like it would be
incredibly uncompassionate and immoral to apply that same argument to say,
you know, the cognitive lead argument, but we make the
health elite argument and say, you know, if you take
the same logic and say people who are west ces
are doomed to be low sees because they have little health, well,
(13:16):
so therefore we should give all interventions to help people
be healthy. I mean that would it's not just politically,
you know, put a correct thing to say. It's called
like just being a fundamentally having humanity, and it misses
that health is at least as much an effect as
it is a cause. Absolutely, Okay, I'd really like to
transition here to the question of is IQ heritable? And
(13:40):
when you're answering this question, you know, when you define
what heritability means, if you could please add some caveats
and nuance that often gets missed in that answer to
the effect, where you let people know that heritability has
nothing to do with the modifiability. Okay, well, yes, I
mean the simple answer the question is that IQ is terrible,
(14:01):
and I mean as good a description of my career
as any is. It's been about understanding the complications of
saying that's some kind of individual difference, like intelligence is heritable.
I mean, that's what I do. And first, my preferred
way of saying what it means for something to be
heritable right now is this that there is a correlation
(14:25):
between how genetically similar any two people are and how
similar their intelligence is. Right, so you can think of
them in the classic way to think about that is
in terms of identical and fraternal twins, and pairs of
identical twins are more similar than pairs of praternal twins,
and the IQs of identical twins are more similar than
(14:45):
the IQ's of paternal twins. You can do with other
kinds of or what you can do with siblings and
half siblings the same thing, and nowadays you can do
it with pairs of people who aren't related, just in terms,
because we can now calculate how much DNA any particular
pair of people share, and you get technically different but
more or less similar answers when you do it that way,
(15:07):
And so that's what it is. It's a correlation between
genetic similarity and similarity in whatever it is that you're
interested in, And as such, it doesn't show that there
are genes for anything in particular, it doesn't really tell
you anything about why it's the case that more genetically
similar people are more similar for whatever. I'm trying to
(15:31):
avoid using the word phenotype here, which is just a
technical word for the observable ways that people are similar.
That's one thing. The other thing that you have to
think about, even while I'll get the malleability in a second,
The other thing that you have to think about when
you think about the heritability of intelligence is what en
That's not something interesting and special about intelligence that Wow,
(15:54):
how do you like that? It turns out that intelligence
is heritable. Everything about human beings is heritable. Any difference
among human beings that you can measure is heritable. So
your personality is heritable, your risk of having a mental
disease is heritable. And then you can get past things
like that, how much television you watch is heritable, how
(16:17):
liberal and conservative you are is heritable. Everything about people
is heritable. And all that means is that in general,
people who are more genetically similar are more similar. Whatever
that as we go through the course of our lives
becoming whatever it is that we've become. I think of
it as our genes have their finger on the scales,
(16:38):
and they are always nudging us in one direction or another,
so that wherever we come out, well, our genes had
a little bit to do with how we got there,
so it's not a specific characteristic of any one thing.
One more before I get the malleability. The next thing
is that now, in the last fifteen or twenty years,
that we can study these things not just with identical
(17:00):
and fraternal twins or parents and children and stuff like that,
but with actual measured DNA biological DNA that we get
out of our bodies. We have made the amazing discovery
that for something like intelligence that's heritable. There are a
lot to be said about this, but in a simple sense,
there are no genes for any of these things. There
(17:23):
is no gene that, in a known biological way, causes
people to be smarter. There are genes that, in a
known biological way cause people to be less intelligent because
it gives them major diseases. But leaving that aside, there
are no big genes for intelligence. You could say there's
a lot of little genes. But I think even that
(17:44):
is too strong. So anyway, the genetics of intelligence exists
in this matrix of everything being intelligent, and that our genes,
like your grandmother said that, you know, the apple doesn't
fall far from the tree. That our genes in very
general ways influence everything we become. Because it's so general,
(18:04):
doesn't have a lot of implications ultimately for the way
we think about ourselves. I think most of us always
knew that our genes placed a certain amount of constraint
on what was likely to happen to us. And it
seems surprising the first time you hear it. Once you
stop and think about I don't really think it's so
surprising at all. So anyway, malleability, I think when you
(18:26):
the first time you think about something being heritable, and
the first time you think about your genes having some
kind of input into an outcome, it's natural to think
of it as well, this is an aspect of us
that's more fixed than we had thought that it might be. Otherwise, Well, gee,
you know, I thought that my intelligence was just the
result of my hard work, or how my parents raised me,
(18:49):
or how good my school is. Well it turns out
it's in my genes. There's not that much we can
do about it. And that is formally, mathematically, bio logically
not the case. The two things. They don't really have
a whole lot to do with each other. There are
a whole lot of very standard examples that I didn't
(19:09):
think up about it. One good one is height. Height
is an obviously heritable thing, and nobody is surprised to
hear that height is heritable, and we don't, in fact
even think of ourselves as being able to do anything
to control our height. But the fact is the height
of various populations of people has changed enormously in a
(19:31):
very short period of time. Japanese people now are about
five inches taller than they were before World War Two.
That's not a genetic change. Height was very heritable before
World War Two, very heritable after World War Two, and
height has increased an enormous amount in Japan over that time.
(19:52):
You can tell the same story in an interesting way
with Dutch people. Before World War two, Americans were on
average several inches taller than the Dutch. They are now
several inches taller than us. It was heritable then, it's
herritble now there's been a big change One more example,
a slightly different one that gets added from a slightly
different angle, is a disease called phenol keatonuia. Phenel keatonuria
(20:17):
is a metabolic disease that, unlike everything else we've been
talking about, is controlled by a single dominant gene. It's
not like all these complex things like intelligence and height.
There is a gene for phenol keatonurea. If you have
the dominant gene, you're unable to metabolize a naturally existing
chemical called phenolalanine that exists in food, and if you
(20:40):
eat foods with phenylalanine, it poisons you and causes severe
metal retardation and eventually death. So that's a very bits
of genetic disorder in a straightforward way. However, it turns
out that if you avoid foods with phenylalanine, everything's fine.
So it's a genetically call disorder, and the treatment for
(21:01):
it is entirely environmental. Good. You said a lot of
really interesting things that I hope clarify, So I want
to further quarify something. So this July behavior geneticis will
nounce over six hundred smps statistically associated with educational attainment,
which we know is correlated with IQ. Even if let's
do the Thur experiment, Even if it comes back and
(21:22):
says one hundred percent of individual differences in educational attainment
is explained by the combination of six hundred small smps,
that still wouldn't mean that the environment couldn't influence an outcome.
Is that correct? Yep? Absolutely so. I think a lot
of people aren't aware of that, And not only not
(21:42):
aware of that, but a lot of my listeners are like,
what the hex and SMP. You could explain that a
little bit. Well, it's literally something called single nucleotide polymorphism.
I usually just refer to it as a snip. I
think that's usually the way people say. A snip is
a single unit of DNA A you know, the in
the ACGT sequence that makes up chromosomes and genes are
(22:08):
long collections long strings of ACGT. There are certain particular
locations that only take one of two values acgt. Those
are referred to as snips. And I'm not, frankly very
good at the biological technical side, so I hope I
don't get any of this wrong. But we are now
(22:30):
able to put I think two million tests for those
snips on a single chip a snip chip and determine
which of the two a particular individual has. And there
have been very, very very elaborate detailed maps that allow
us to go from which particular values of snips you
have at different locations on your chromosome and how that
(22:53):
maps on to what genes you're carrying. So the sort
of current state of the art in gene hunting is
to do the hunting at the level of snips, and
simply it's a very simple process of looking for individual
paired snips and where one value seems to be associated
(23:15):
with having a higher educational attainment than another value, and
then there's inferential work can be done on top of
that to try and identify genes, though that starts to
get very very complicated. There's I think one other important
thing to say about this overall process. By the way,
I don't think you used. This is called juas or
(23:37):
association study. Is this process of searching for snips associated
with and so we're now doing this process for all
of the many human traits that we discovered were heritable
fifty years ago, using twins and siblings and adopt these
(24:00):
and all that kind of stuff. And it's interesting that
we're able to do this now, and it may well
turn out as time goes by that we learn important
things from doing this. But it's not surprising for all
these heritable traits that we're able to find snips that
are associated with them once we knew that intelligence was heritable.
(24:24):
Another way of saying that is to say, well, there
are differences in DNA that are associated with intelligence. We
knew that was true, and so a lot of modern
snip finding, from my point of view, is a matter
of confirming what we already knew. It's finding out the
same things about heritability that we already knew from twins
(24:49):
and siblings and families. I think there's a tendency to
sometimes that, even now that people have gotten used to
the idea that behavior is broadly heritable, to make the
same mistake you were suggesting of thinking, wow, now that
we're finding out that there are actual little bits of
DNA that are associated with these behaviors, that must really
be fixing it. You know that we're really finding the
(25:12):
education genes or more and more commonly, the IQ genes here,
and I personally don't really think we are. I think
it's safe to say the jury is still out And
I think there are a lot of people who think
that at least we're at the beginning of a road
that's going to end up with a actual genetic biological
understanding of something like educational attainment. I myself am quite
(25:36):
a bit more skeptical. But you would never you could
never do without the socialization process in this no matter
what is found. If you want to increase educational team.
Even if it turns out that some people have greater
genetic potential for the ultimate heights of learning and rate
of learning, et cetera, et cetera, that still doesn't mean
(25:57):
that we should provide the most challenging opportun coortunities for everyone, right, Oh,
of course not so. I think that kind of gets
missed sometimes in these discussions. Is you know, we can
get so lost in the weeds that so like so
what you know, like, you know, what's the practical implication here? Now,
some people have written some thoughtful books about a genetic
understand how genetically informed understanding of school could lead us
(26:21):
to teach an individualized learning for different people, et cetera,
et cetera. And I think there are some thoughtful things
out there about that, but still doesn't get rid of
the teaching part. No, of course not. I know you say,
of course not, but I do think that is missed
in somebody's well yes, no, and no. I mean I say,
of course not by way of agreeing with you. But
it it's an incredibly difficult and complicated problem. I mean,
(26:44):
I've spent my entire professional life trying to think about
exactly what it means that our genes might be related
to how much education people wind up obtaining. And you know,
if you put me on the spot and say, okay,
you've got three minutes explain exactly how that works, I'm
(27:06):
not sure I could do it. And it's a very
very deep and difficult theoretical problem. When you have a
problem like that, I think what happens is that the
two poles of the problem, the two easy ends of it,
become magnets for people. And you find people saying, oh, yeah,
we got the genes, you know, and people are just
(27:27):
born that way, and some people are born smarter than others.
And then you have people on the other side saying,
how could you say such a thing that the genes
have something to do with educational attainment, That that's determinism
and et cetera, et cetera, et cetera, and want to
argue that genes must have nothing to do with it,
and neither of those two polls is ever a good
(27:49):
answer good. I would not want it to be the
case that our intelligence was one hundred percent determined by
either the environment or one hundred percent determined by our genes.
Either situation would really suck if you think about it, right,
I mean, then you would have no free will either way.
Kind of. But people don't realize is that the way
the reality of the world is is actually pretty neat
(28:11):
in a way. There is something that it means to
be you, but there's also a lot that you can
do to construct yourself and become who you consciously want
to be. And also, I want to say I abhore
the process of the idea that someday we'll be able to,
as early as possible, measure people's genes and then use
that as a forecasting utility value to differentiate people into
(28:33):
different tracks as early as possible based on their genetics. Now,
I really really do not advocate for that. I agree
with you, Yeah, not just from like a there's a
moral standpoint, but just from like a human potential standpoint.
I'm not convinced that doing that would maximize Yeah, it
would be. I mean, the fact is people think of
it as something we could do off in some science
(28:55):
fiction future. But the fact is we could do it today.
About how we could do it today shows I think
why it's morally wrong. Here's how you predict kids' school
performance from their genes. You look up their parents' IQ scores,
and parents' IQ scores are really powerful predictors of children's
(29:16):
IQ scores. I mean really much much, much better than
anything we could do with genomic information. And much of
the reason for why parents IQ scores predict kid's IQ
scores are genetic. So why not just say, well, we
should take parents who are really smart and give best
resources to their children because they have the best genetic potential.
(29:39):
You can't do that because people have a right to
make the best of what they are, regardless of your
judgment of what their genetic potential is. I couldn't agree more.
Maybe I don't know if this is plain Devil's out
it be kid a little bit, But I want to
ask you a question I just thought of. So if
we agreed that the inhritability coefficient of a pt or population.
(30:00):
And by the way, heartability is a population variable related variable,
and it has to do with individual differences. There's no
other thing as a heritability within a person, just like
there's such a thing as a cube within a person.
And it also means that for me, the question what's
the heritability of intelligence is a really bad question. Intelligence
doesn't have a erritability. It's like a property of it
(30:24):
that it carries around from place to place. The heritability
of intelligence depends on the particulars of the situation in
which of the population in which that intelligence is measured. Absolutely,
so that's one part of it. But so if we
can agree that heritability is not a good proxy for
the ability to change, then you've shown done research interests,
(30:47):
a very interesting research showing that heritability coefficients are not
the same magnitude across social classes. Now, even if that
is true, and I'm kind of playing table's advocate for
a second, Even if that is true, and we already
just concluded that ritable is not a proxy for the
ability to change, then what's even the practical implication of
your own findings in that regard? Do you know what
I'm saying, yes, it's funny. I mean, if I'm honest
(31:09):
as somebody who's sometimes critical of people obsessing about what
the heritability of this or that is, I do think
it's hard to say exactly what it means that the
heritability of intelligence, which is what that research is about,
is different in some places than others. But I do
think you can put meat on the bones of that finding.
(31:30):
And the finding is that the heritability of intelligence, and
I should add it seems like it's in the United
States is lower in poor people than it is in
well off people, middle class and better people. Doesn't seem
like that happens in Europe, which is the main other
place that's been studied, probably because there's less economic and
equality there, and especially educational inequality. And I frankly can't
(31:54):
prove this. I think this is informed speculation about what
that might mean. A variant on a standard example for
thinking about genetic differences. I suppose you have a bunch
of seeds that are vary genetically for how tall plants
are going to be, and you plant them in really
excellent soil, and some plants wind up taller than others,
(32:17):
and that they're all in the same soil, the same
good soil, and some wind up taller than others, and
that's genetic variation in the seeds. You then take the
same handful of seeds or another handful out of the
same population and plant them in sand. Well, two things
are going to happen. First of all, they're all going
to be shorter, we all know that. But they're also
(32:38):
going to be less varied because they're all going to
be stunted. Even the seeds that had the genetic potential
to produce tall plants in the good soil are going
to wind up stunted. And of course if the soil
is bad enough, they're not going to grow at all.
So it makes sense that individuals need a reasonably supportive
(32:59):
and vironment in order to express their genetic variability. And
if people are in an environment that doesn't permit them
to seek out the environments that they can use to support,
as you said, who they're going to become, well, then
that's going to cut down on the variability. And with
(33:20):
heritability as a way of describing variability, so you know,
I think that's what's going on. Then you can take
a kid who has the potential to be a genius
and raise that kid in an environment with a different
family and crummy schools and a terrible neighborhood, and that
(33:41):
kid is not going to be able to find the
resources to help him or her become really, really smart.
And so it's a leveler. I say the rest of
this podcast, let's talk about the most controversial topics, because
I think that's it feels right to transition into those now.
So when we talk about sees the cause of SES
differences in this idea, you know, Charles Murray has the
(34:04):
CTD of the cognitive elite as kind of being a reason. Now,
it's a reasonable thing to say that there are IQ
differences between different SES groups. Just to say that is reasonable,
But to me, it seems to ignore all the you know,
it kind of puts too much focus on this one variable,
you know, when there are so many other variable one
(34:27):
could pick any one variable and write a whole book
of assigned the key causal role to that barrier. It
doesn't see intelligence as part of the network of good
things that happen to people when they're in a successful
society and have resources. It sees them as the cause
(34:50):
for why they're in that position. In the first place.
And you know, it brings us back to just everything
we were talking about the beginning. That g is this
property that exists inside people and causes them to express
all those good things that happen to them. That's the
Bell curve basically. And like you say, I mean, it's
not a I don't think that's a crazy idea or
(35:12):
a evil idea particularly. I just think it's wrong. I
just think it mischaracterizes the role that intelligence actually plays
in life. It's not the inner causal agent that causes
any more than health is to say. You know, like
you say, you could talk about there's a health elite, right,
not even health. We could add to this list any trait.
We could say aggression. Let's take aggression. I've seen some
(35:35):
fabulous research come out recently by Daniel Nettell and others
from an evolutionary point of you're showing just minor social
economic changes you make that reduce the aggression level significantly.
Now in some studies, I've seen their aggresion levels produced
so much that there's no difference anymore between well SS
and high SS. Once you make some minor system wide
(35:55):
tweaks to a really unstable and harsh environment, that people
are living in. So one could make argument they are
the way they are because they have low impulsivity, because
they have aggression. But if you instead view it as
the smaller we're talking about as these are all outcome
indicators kind of barometer, a barometer of what environmental experiences
interacting with genes that we all have, that any of
(36:17):
us could become in a way with certain environment Christians,
that's a different way of thinking about it, right, Yeah,
it's a much more complex way of thinking about it,
and it doesn't locate all the causation in one particular variable.
So let's go to the most controversial topic. Let's go
right there. Okay, race differences in IQ. Now, look again,
(36:41):
it is not an unreasonable thing to say that there
are race differences in average IQ scores between whites and blacks.
That's just an observation fact. And that gap does not
seemed to narrow in the past twenty five years. Okay,
I narrowed a little bit. It's not a topic I'm
an expert on, but some of my common co authors,
(37:02):
Jim Plann, dick nisbet Bill Dickens, who know more about
that than I do, I think, argue very persuasively that
it's down by a third over the last thirty four years. Okay,
so it's down, but there's still exists. Way, it hasn't
gone away. Okay, now there, and then there's the other question,
what are the causal forces? Just we have the same
(37:23):
discussion about sees Lyell and let's you know, we could
talk about group. Okay. The thing about this issue is
that Okay, so first of all, we know that just
because IQ is heritable, there's nothing in what we learn
about the hritle bit of IQ that can be directly
applied to understanding whether or not genes explain the difference
between blacks and whites. So we can have a whole
(37:45):
discussion as we are having on this podcast, agreeing that yes,
there is a genetic contribution to individual differences in IQ
in the general population, and that doesn't have anything to
say about whether or not to the extent to which
genes explain differences between different groups. Now, do are we
grid in that as well? Absolutely? So here's a question
I have is racist social construction. Does it make sense
(38:08):
even in the first place, to look for genetic environmental
factors that explain difference between whites and blacks in America. Well,
I mean, I'm not sure I have the same You
ask two questions, and I'm not sure I have the
same answer to both of them. The first one is
race to social construction, and the second doesn't make sense
to talk about genetic environmental great point, because one could
(38:29):
be yes, the other one can be right yes as well.
I'm a moderate sort of on that whole social construction business.
And in some funny way, that's a question that people
have argued about for so long, and it doesn't really
seem very complicated to me. In a way. There are
a lot of things that we know are true. The
human evolutionary story is a real thing, and we know
(38:52):
a lot about where human beings came from and how
they came out of Africa and how they spread around
the globe over a very very long evolutionary time span.
It's also the case that in more recent times, people
who live together in certain parts of the world are
more genetically related to each other. People who live in
(39:12):
Lithuania and think of themselves as Lithuanians are more like
each other than they are like Japanese people who are
like each other, and so it's not like the difference
between Japanese people and Lithuanians. Is this imaginary social thing
that we made up. There's biological reality, but the evolutionary
(39:34):
story and the geographical sorting of people around the world
is by and large continuous and dynamic. There aren't bright
lines dividing groups of people Lithuanians from Slovs. From those
lines that we impose on that biological reality are yes,
(39:57):
socially constructed. Now does that make them wrong? No? Does
it make them useless? No? It makes them artificial boundaries
that we impose on a very complex biological reality. So
one more example, just to make the point that I
was just thinking about. It's a kind of a trivial example,
(40:19):
but I think it gets the point. Ski slopes are
very complicated things. They differ in slope, they differ in
how many moguls they have, they differ in how long
they are, they differ in how narrow they are, all
sorts of things, and there are all sorts of ways
we could think about the difficulty of ski slopes. But
what do we do. We come up with yellow, blue,
and black, and we classify ski slopes as though there
(40:43):
were just three kinds yellow, blue and black. Now, if
we ask, are there really three kinds of ski slopes
in the world and only three kinds of ski slopes?
Of course not right. Ski slopes are much more complicated
than that. But sometimes under some circumstances, it's useful to
break them up in these those groups, as long as
we remember that the three part and the exact borderline
(41:07):
between yellow and blue is not given by nature. That's
something that we do. So that's the answer to that
A too long answer to the is it a social
construction question? Should I go on to looking for intelligence difference? No,
because I want to talk about the nittigree of this
now again. I refer people for a really nuanced review
of the current state of evidence. I refer people to
(41:29):
read Nicholas mcintosha's second edition of IQ and Human Intelligence.
He's a whole chapter on this, and I was say,
in a nutshell, after reviewing carefully all the evidence, there
is no good evidence that genes whatsoever play a role
in explaining differences between blacks and whites. The perspective I'm
coming from is, you know, education is such a crucial
(41:52):
gateway to opportunities in life. When I see the evidence
that blacks and whites differ on average in educational attainment
standardized test scores. Things like this, I immediately go into
like intervention mode, like I want to know, like what
are the whole causal factors? What are the things we
can do to change the culture, perhaps in some ways
(42:12):
to motivate show people who are in low sees environments,
for those who are difficult circumstances, that there's a future
for them. And all these factors have been shown to
help reduce the gap, little by little, lots of little
factors add up. Now the question is, even if they
don't all add up one hundred percent? To explain the differences,
I have this so what question? And Charles Murray was
(42:32):
recently on the Sam Harris podcast As You Know, and
Sam Harris asked him, you know, the so what question?
And the only answer Charles Murray had to the purpose
of finding out detaining the genetic information was implications for
college entrants for you know, And I don't feel like
I understood whatsoever. I still left that podcast not understanding
(42:53):
the so what question? Can you convince me at all
that there's any practically meaningful societal other than just knowledge
for the sake of knowledge of knowing that even like
five percent of the differences between different groups can be
not one hundred percent deterministic but are influenced by gene differences.
I have, again, I've complicated feelings about this. I'm I'm
(43:16):
not one who would think that there's ever a valid
scientific reality out there that we shouldn't go to because
the consequences are bad and we don't see the utility.
I mean, And in addition, as a practical matter, I
think it's generally impossible to keep those genies in the
(43:36):
bottle anyway. And if it's true and real, sooner or
later it's going to out and everybody's going to know
it anyway. So and I guess I do think that
for something that is on a sound theoretical footing and
has real meaning and it's true, we should go there.
And so I actually don't like the defense against genetically
(44:00):
based race differences, which says this is a bad thing there,
nothing good can come of it. Why should we know it?
I mean, if it were true and if it made sense,
and I don't think it makes sense, it's going to
happen anyway. By the way, I agree, I don't think
that knowledge should be censored and I encourage more research
on whatever someone wants to research. So I want to
(44:20):
be very clear about that. My question, the so what
question I'm asking is not the so what in terms
of like we shouldn't be doing the research. It's like,
you know, the so what is like I've been asking
so what a lot today, Like when we talked about
the fact that i Q might be heritable, Well, how
does that help me, as an individual think about what
is possible within me? So my question is people act
(44:41):
as though it'd be so forbidden if we found that
some small proportion of race differences was correlated with genetic differences.
But I'm trying to say, is even if we gosh
forbid found that, would that change change? I think would
be really bad. Frankly, tell me more, because what would it?
I mean again, I ultimately don't think this concept of
(45:01):
genetically based differences between groups makes any sense, and it
makes me nervous about talking about the consequences as though
it did make sense. But if we really knew that
an entire group, the only thing I can imagine that
meaning that statement meaning is that this group of people
has lower IQ than that group of people, and there's
nothing you can do about it. That's not what that
(45:22):
would mean, right, Well, I think would If it doesn't
mean that, then what sense does it make to say
that the mean difference is based in the genes, right,
If you can make it go way environmentally, then it
wasn't based in the genes in the first place. We
really don't know that because of the genes an individual
has that there's a limitation to what their IQ could
(45:44):
be under any possible environment that we could expose them to.
We don't know that short of them having some major
genetic disorder or something. And actually, I think that's a
very important idea that it's very important that we know
basically at asolutely nothing about the biology of why some
people are smarter than others from a genetic point of view,
(46:07):
because that really means that, as a matter of potential,
our malleability is practically unlimited. And it brings us back
to your original point that knowing that intelligence is heritable
does not put a limit on the malleability of that intelligence. Right. So,
(46:28):
if what you said is true that the heritability of
IQ is independent of the malleability of IQ, it's not
the case that printing out my genome when I was born,
gives you information that allows you to say that it's
impossible that the world might have turned me into a
(46:52):
Nobel Prize winner much smarter than I actually am. And
what we know about group differences in intelligence is that
the magnitude of them is smaller than we absolutely know
the malleability of intelligence to be in a number of ways,
that when children are adopted out of poor homes into
(47:15):
well off homes, the amount of change in their IQs
is larger than the modern difference between blacks and whites.
The difference in the average iq of white people in
the United States now and white people in the United
States in nineteen fifty is larger than the difference between
(47:36):
blacks and whites. So that we know, we know that
average IQs are malleable well within the range of that difference.
So knowing that, I simply don't see how it makes sense.
And you know, and when you were talking before about
mining to turnout, well that it's just a few percent,
just five percent, the whole percent thing, which is problematic
(47:58):
enough at the individual level, it makes no sense at
all at the group level. There is no group heritability
coefficient that can come out to be equal to a
particular number. If you go look at the articles the
very by the people who really believe in genetic differences
between the races, and in their own way take a
(48:19):
very scholarly and serious approach to the problem. It's not
like they're listing studies and saying this one shows that
it's twelve percent heritable, and this one shows that it's
twenty eight percent heritable. Because there's no mathematical model to
produce those numbers, the idea of the group difference being
x percent heritable doesn't make sense in terms, there's no
(48:40):
quantitative genetics that produces those numbers. One more and then
I'll stop, because I think this is the key important idea.
You know, if it made sense that groups might differ
in complex behavior, that the groups like different complex behavior
in a way that's partially in some percentage, wouldn't it
be the case that there were other group differences in
(49:01):
behavior that we'd already figured out. You know that Japanese
people are more introverted than people from the Dominican Republic.
Oh yes, and we've done some research and it turns
out that's genetic. On the other hand, you know, Chinese
people are better table tennis players than people from Kenya,
And hey, how do you like that we did the
(49:22):
research and that turns out to be environmental? Right, there's
not a single complex human trait that has ever been
shown to be genetic or environmental in any proportion, because
to me, it's not really an empirical question. The empirical
question is how malleable are these things? And to the
extent we know they're malleable, and things are way more
(49:43):
malleable than we think, to the extent they're malleable, we
can't prove that they're fixed genetically. Eric, I love that point.
I want to end on the point that the idea
of how niable things is a separate issue. I think
that's a theme of this whole discussion today, separate issue
from what's the herod ability? Explit good? And I want
to leave for the last thirty seconds on a very
(50:04):
personal note. I don't want to belabor it, but I
would be remiss not to say that I personally saw
what it was like to grow up with people expecting
very low things from you because of your IQ score,
because of a learning disability and auditory learning disability. I
had a very low measured IQ and that really I
was labeled a slow learner, and it really did affect
(50:25):
how people looked at me and treated me, and then
it affected my own self esteem and then what I did.
And it took a couple of people to really believe
in me and kind of look past the labels before
I was inspired to see what I was capable of achieving.
So I want to just say that some of these
researchers might want to spend some time digging more into
different perspectives. I look forward to reading your book. It
(50:45):
looks fascinating. Thank you so much for such an interesting
chat today. Okay, good, that was a pleasure. Thanks very much.
Thank you for the chat. Have a good day. Okay, yep,
I'll be in touch. Bye bye. Thanks for listening to
The Psychology Podcast with doctor Scott barrk Kaufman. I hope
you found this episode just as thought per booking and
interesting as I did. If you'd like to read the
show notes for this episode or hear past episodes, you
(51:07):
can visit the Psychology Podcast dot com.
Hello, and welcome to the Psychology Podcast with Doctor Scott
Barry Kaufman, where we give you insights into the mind, brain, behavior,
and creativity. Each episode will feature a new guest who
will stimulate your mind and give you a greater understanding
of yourself, others, and the world we live in. Hopefully
we'll also provide a glimpse into human possibility. Thanks for
listening and enjoy the podcast. So today it's great to
(00:40):
have doctor Eric Turkheimer on the podcast. Doctor Turkhimer is
the Hugh Scott Hamilton Professor of Psychology at the University
of Virginia. His lab studies how interactions between genes and
environments shape the development of human behavior. Today, we'll be
focusing mostly on Turkimer's research on intelligence, genetics, and family background.
The topic of intelligence is a favorite here the Psychology Podcast.
(01:01):
Some of our previous guests discussing this topic include Christopher
Shaburri and Stuart Ritchie. I personally have studied this topic
since the beginning of my career, so I'm always eager
to engage in respectful, mature discussion on the topic. If
you'd like to join in the discussion, please go to
the Psychology podcast dot com and leave comments on the
post for this episode. Eric. Great to have you on
(01:21):
the show today. Nice see us, Scott. Let's jump right
into this. What is intelligence? How do you define it?
What's your personal conceptualization? I think intelligence is the ability
to process information and solve problems. I mean, that's pretty basic,
(01:42):
I guess. I mean there's more technical definition of intelligence,
of course, but I don't know. I guess I think
that's a pretty good starting place, Okay. And then there's
so there's two issues of the question of a definition,
and there's the issue of measurement. Now what do you
think are some of the best measures of what you
just defined that are out there right now? Well, I
(02:05):
don't know. I don't know what you mean specifically. But
there's of course an entire universe of intelligence tests IQ
tests so called, of various different kinds, and those range
from formal IQ tests that you might take with a
professional psychologist too. In my opinion, things like the SATs
(02:28):
that you take in high school are more or less
a kind of intelligence test. They're formulated and conceptualized a
little bit differently. So it sounds like you're saying IQ
test that's the answer, it sounds like you're saying because
one could say that it's you know that IQ is
a very limited measure of intelligence, and there's been arguments
in that effect and et cetera. So I just want
(02:50):
to make sure that we're on the same page, that
everyone understands exactly what you're saying at every step of
this way. Yeah, and I think if this is where
you're headed, that some of the more general things that
people sometimes talk about as intelligence, social intelligence, and in
our personal intelligence and emotional intelligence, those are all really
important things in the world. But I guess I do
(03:13):
think of those as separate from what I think of
as intelligence per se, which is more about problem solving
specifically than it is about the kind of much broader
activities that people have to conduct in the world. Yeah. Sure,
but you know, so one could make the argument that
(03:34):
certain kinds of problem solving are very contextual, based on
the mean specific areas of human adaptation throughout the course
of human evolution. So it sounds like when you say
problem solving, you talk about a general problem solving ability
that's captured by what we can talk about the G factor.
We can talk about the chief factor if you want yeah,
we should talk about the G factor because I have
(03:55):
fairly particular ideas about the G factor that may aren't
necessarily the same as other people you might talk to
about it. Great, I'd love to hear what your thoughts
are on the G factor, and you can understand why
I want to make sure we qualify how you think
about intelligence and how you think we should measure it,
because you know there is no objective, you know ten
(04:17):
commandments that God gave us saying this is the measure
of intelligence, and this is how we should defind So
you know, that's why it's very important for people to
quarify their terms. So tell me what the G factor is? Well,
I mean, what the G factor definitely is? I mean,
and I think the question is whether it's more than this,
But what it I think it indisputably is. Is a
(04:41):
statistical construct that describes the fact that ability tests, very broadly,
ability tests are positively correlated with each other, and people
who do well on one ability tests tend to do
well on other ability tests. People often speak as though
the positive of correlations among ability tests mean that there
(05:03):
is only one kind of intelligence that explains all of
why tests go together and I don't think that's the case,
even though it's the case that the correlations among different
ability tests are positive. But in any event, as a
statistical matter, anytime you have a number of tests that
are positively correlated with each other, it's possible in a
(05:26):
statistical way to extract from that matrix of tests something
that's called the first principal component, which describes the way
that those tests correlate together. And that literally is what
general intelligence or G is. It's the first principal component
(05:47):
of a matrix of positively correlated intelligence tests. Now, at
that point, I think there comes a theoretical fork in
the road in the history of thinking about intelligence. That
one school of thought about intelligence, and I think probably
it's safe to say the dominant school of thought about
(06:09):
intelligence that goes back to Charles Spearman, says that this G,
this statistical G thing that describes the positive correlation among
a whole bunch of ability tests, must represent some kind
of actual thing inside human beings that causes those tests
(06:29):
to go together, something in our brain that represents G,
something in our genes that represent G. I don't agree
with that conclusion. I think it's much better to think
of G as a descriptive thing rather than a causal thing.
G is a way of describing the way mental tests
(06:50):
go together. It's not a way of explaining why mental
tests go together. Beautiful. That is in line with a
lot of recent research on statistical modeling of G showing
that it's a better model to look at G as
reflective variable, you know, in a structural equation model, as
sort of the emergent property of multiple indicators of cognobility
(07:10):
as opposed to the causal force. So even from like
a from a statistical model and then from a brain
model theory kind of oh, you know, I'm referring to
recent statistical models of G that have tried to model
it as either a causal force or an outcome, you know,
and research shows that it does make more sense to
think of it, you said, descriptive, and that's exactly what
(07:31):
the research suggests, is a better way of things as
an emergence. You know, it's not a thing, it's an
emergent property. And also it's that seems in line with
the recent research on G not making any sense as
existing in an individual brain. It has to do with
individual differences, you know. Even Arthur Jensen, who a lot
of people malign or you know, who's done a lot
(07:52):
of good scientific work on this topic. And we can
get to some of his more controversial stuff later, but
he has done some significant scientific work. You know. He
made the case that G intelligence has no meaning if
you're the only one in a desert island, if you
can't compare your G leveled anyone else in that island,
it makes no sense to you can't measure your G.
So all that I just want to say is consistent
(08:13):
with what you just said. Yeah, and I think to
get back, I think I've placed a marker on something
while we're getting to where we are about the uni
dimensionality of G and intelligence, because I think that's very
important that, you know, going back to Charles Spearman, who
came up with this idea in the first place. People
have asked, once again a statistical question about whether all
(08:34):
of the various covariation along the many the infinite number
of mental tests that you could give to people can
be fit by a single common factor. And the answer
to that question, going back to Spearman, is no. In fact,
as domains of tests go, it's true that intelligence is
fairly well fairly well described by a single factor, more
(08:58):
than say personality or something thing. But Spearman himself showed
that G per se, one single factor was not enough.
And I think, people, well, it's two things. People. It
can be very easy to think that because all tests
are positively correlated with each other, that means that there
(09:19):
must only be one thing that's causing them, and that,
as a statistical matter, is not the case. And second,
once you come up with this statistical thing called G
and describe it mathematically and name it as G, it's
very easy to fall in love with it a little
bit and think that, well, now that we have this
(09:39):
thing called G, and it does describe quite a bit
of the variation and intelligence, that it must be the single,
one and only thing and the whole domain of describing
something as complicated as intelligence with latent factors like G,
it's way more complicated as soon as you have more
(09:59):
than one factor to work with. Great points, And I
really like the Johnson and Bichard model that has really
done some systematic analyses of the fundamental group factors of
G and shown in verbal, nonverbal, and spatial are some
pretty essential group factors. Yeah, so you one can reduce
all these different cognitive ability tests to a single dimension,
(10:20):
and one can do that and that does have predictive value.
Something my mentor Nickel I did my master's agree with
Nicholas McIntosh at Cambridge, who I think wrote the best
textbook on this topic. And you know, he constantly has
made that point that you know, G, this positive manifold
doesn't stop with cognitobility. There are a whole nexus of
(10:42):
socioeconomic status. I mean, this normalogical network of G is
very broad. And one thing that is difficult to do
is disentangle, you know, all of these causal forces and
disentangle which is causing what you know within this normalogical network,
because that it's no easy feed, is it. No? That's right, yeah.
(11:04):
And one school of thought that I'm sure we'll get
into is to sort of take G and put it
at the center of that universe and say that everything
else that happened is caused by this G thing, rather
than seeing G as part of a much broader descriptive network. Good.
(11:25):
And you know, one analogy that I've been kicking around
some is with the idea of health. Let's say you
took a whole bunch of medical measurements from people. You
got their blood pressure and their BMI and their lung
capacity and how fast they could run, and all those
various things, and got correlations among all those things. They
(11:48):
would be I would imagine positively correlated. Maybe not quite
as positively correlated as mental tests are, but you'd still
be able to take a first principal component out of
them that describe the way all these various health measures
go together, and you can call it health. And some
people at any given moment are healthier than other people.
(12:09):
We're very accustomed to talking about it this way, and
on surveys you ask people a single question, you know,
how good would you how would you describe your health
on a scale from one to ten. But it wouldn't
occur to us to think of health as this special
inner quality that people carry around, And it wouldn't occur
to us to start looking for the health center in
(12:32):
people's brain body, or start to ask, well, what are
the specific genes that cause people to be healthier than
each other. We recognize health as just what you say.
It's a health is a way of describing a certain
domain of covariation in a very complicated network of things.
(12:54):
But it's not a cause of those things, it's a
description of those things. I love that. And then it
also taking that analogy, it seems like it would be
incredibly uncompassionate and immoral to apply that same argument to say,
you know, the cognitive lead argument, but we make the
health elite argument and say, you know, if you take
the same logic and say people who are west ces
are doomed to be low sees because they have little health, well,
(13:16):
so therefore we should give all interventions to help people
be healthy. I mean that would it's not just politically,
you know, put a correct thing to say. It's called
like just being a fundamentally having humanity, and it misses
that health is at least as much an effect as
it is a cause. Absolutely, Okay, I'd really like to
transition here to the question of is IQ heritable? And
(13:40):
when you're answering this question, you know, when you define
what heritability means, if you could please add some caveats
and nuance that often gets missed in that answer to
the effect, where you let people know that heritability has
nothing to do with the modifiability. Okay, well, yes, I
mean the simple answer the question is that IQ is terrible,
(14:01):
and I mean as good a description of my career
as any is. It's been about understanding the complications of
saying that's some kind of individual difference, like intelligence is heritable.
I mean, that's what I do. And first, my preferred
way of saying what it means for something to be
heritable right now is this that there is a correlation
(14:25):
between how genetically similar any two people are and how
similar their intelligence is. Right, so you can think of
them in the classic way to think about that is
in terms of identical and fraternal twins, and pairs of
identical twins are more similar than pairs of praternal twins,
and the IQs of identical twins are more similar than
(14:45):
the IQ's of paternal twins. You can do with other
kinds of or what you can do with siblings and
half siblings the same thing, and nowadays you can do
it with pairs of people who aren't related, just in terms,
because we can now calculate how much DNA any particular
pair of people share, and you get technically different but
more or less similar answers when you do it that way,
(15:07):
And so that's what it is. It's a correlation between
genetic similarity and similarity in whatever it is that you're
interested in, And as such, it doesn't show that there
are genes for anything in particular, it doesn't really tell
you anything about why it's the case that more genetically
similar people are more similar for whatever. I'm trying to
(15:31):
avoid using the word phenotype here, which is just a
technical word for the observable ways that people are similar.
That's one thing. The other thing that you have to
think about, even while I'll get the malleability in a second,
The other thing that you have to think about when
you think about the heritability of intelligence is what en
That's not something interesting and special about intelligence that Wow,
(15:54):
how do you like that? It turns out that intelligence
is heritable. Everything about human beings is heritable. Any difference
among human beings that you can measure is heritable. So
your personality is heritable, your risk of having a mental
disease is heritable. And then you can get past things
like that, how much television you watch is heritable, how
(16:17):
liberal and conservative you are is heritable. Everything about people
is heritable. And all that means is that in general,
people who are more genetically similar are more similar. Whatever
that as we go through the course of our lives
becoming whatever it is that we've become. I think of
it as our genes have their finger on the scales,
(16:38):
and they are always nudging us in one direction or another,
so that wherever we come out, well, our genes had
a little bit to do with how we got there,
so it's not a specific characteristic of any one thing.
One more before I get the malleability. The next thing
is that now, in the last fifteen or twenty years,
that we can study these things not just with identical
(17:00):
and fraternal twins or parents and children and stuff like that,
but with actual measured DNA biological DNA that we get
out of our bodies. We have made the amazing discovery
that for something like intelligence that's heritable. There are a
lot to be said about this, but in a simple sense,
there are no genes for any of these things. There
(17:23):
is no gene that, in a known biological way, causes
people to be smarter. There are genes that, in a
known biological way cause people to be less intelligent because
it gives them major diseases. But leaving that aside, there
are no big genes for intelligence. You could say there's
a lot of little genes. But I think even that
(17:44):
is too strong. So anyway, the genetics of intelligence exists
in this matrix of everything being intelligent, and that our genes,
like your grandmother said that, you know, the apple doesn't
fall far from the tree. That our genes in very
general ways influence everything we become. Because it's so general,
(18:04):
doesn't have a lot of implications ultimately for the way
we think about ourselves. I think most of us always
knew that our genes placed a certain amount of constraint
on what was likely to happen to us. And it
seems surprising the first time you hear it. Once you
stop and think about I don't really think it's so
surprising at all. So anyway, malleability, I think when you
(18:26):
the first time you think about something being heritable, and
the first time you think about your genes having some
kind of input into an outcome, it's natural to think
of it as well, this is an aspect of us
that's more fixed than we had thought that it might be. Otherwise, Well, gee,
you know, I thought that my intelligence was just the
result of my hard work, or how my parents raised me,
(18:49):
or how good my school is. Well it turns out
it's in my genes. There's not that much we can
do about it. And that is formally, mathematically, bio logically
not the case. The two things. They don't really have
a whole lot to do with each other. There are
a whole lot of very standard examples that I didn't
(19:09):
think up about it. One good one is height. Height
is an obviously heritable thing, and nobody is surprised to
hear that height is heritable, and we don't, in fact
even think of ourselves as being able to do anything
to control our height. But the fact is the height
of various populations of people has changed enormously in a
(19:31):
very short period of time. Japanese people now are about
five inches taller than they were before World War Two.
That's not a genetic change. Height was very heritable before
World War Two, very heritable after World War Two, and
height has increased an enormous amount in Japan over that time.
(19:52):
You can tell the same story in an interesting way
with Dutch people. Before World War two, Americans were on
average several inches taller than the Dutch. They are now
several inches taller than us. It was heritable then, it's
herritble now there's been a big change One more example,
a slightly different one that gets added from a slightly
different angle, is a disease called phenol keatonuia. Phenel keatonuria
(20:17):
is a metabolic disease that, unlike everything else we've been
talking about, is controlled by a single dominant gene. It's
not like all these complex things like intelligence and height.
There is a gene for phenol keatonurea. If you have
the dominant gene, you're unable to metabolize a naturally existing
chemical called phenolalanine that exists in food, and if you
(20:40):
eat foods with phenylalanine, it poisons you and causes severe
metal retardation and eventually death. So that's a very bits
of genetic disorder in a straightforward way. However, it turns
out that if you avoid foods with phenylalanine, everything's fine.
So it's a genetically call disorder, and the treatment for
(21:01):
it is entirely environmental. Good. You said a lot of
really interesting things that I hope clarify, So I want
to further quarify something. So this July behavior geneticis will
nounce over six hundred smps statistically associated with educational attainment,
which we know is correlated with IQ. Even if let's
do the Thur experiment, Even if it comes back and
(21:22):
says one hundred percent of individual differences in educational attainment
is explained by the combination of six hundred small smps,
that still wouldn't mean that the environment couldn't influence an outcome.
Is that correct? Yep? Absolutely so. I think a lot
of people aren't aware of that, And not only not
(21:42):
aware of that, but a lot of my listeners are like,
what the hex and SMP. You could explain that a
little bit. Well, it's literally something called single nucleotide polymorphism.
I usually just refer to it as a snip. I
think that's usually the way people say. A snip is
a single unit of DNA A you know, the in
the ACGT sequence that makes up chromosomes and genes are
(22:08):
long collections long strings of ACGT. There are certain particular
locations that only take one of two values acgt. Those
are referred to as snips. And I'm not, frankly very
good at the biological technical side, so I hope I
don't get any of this wrong. But we are now
(22:30):
able to put I think two million tests for those
snips on a single chip a snip chip and determine
which of the two a particular individual has. And there
have been very, very very elaborate detailed maps that allow
us to go from which particular values of snips you
have at different locations on your chromosome and how that
(22:53):
maps on to what genes you're carrying. So the sort
of current state of the art in gene hunting is
to do the hunting at the level of snips, and
simply it's a very simple process of looking for individual
paired snips and where one value seems to be associated
(23:15):
with having a higher educational attainment than another value, and
then there's inferential work can be done on top of
that to try and identify genes, though that starts to
get very very complicated. There's I think one other important
thing to say about this overall process. By the way,
I don't think you used. This is called juas or
(23:37):
association study. Is this process of searching for snips associated
with and so we're now doing this process for all
of the many human traits that we discovered were heritable
fifty years ago, using twins and siblings and adopt these
(24:00):
and all that kind of stuff. And it's interesting that
we're able to do this now, and it may well
turn out as time goes by that we learn important
things from doing this. But it's not surprising for all
these heritable traits that we're able to find snips that
are associated with them once we knew that intelligence was heritable.
(24:24):
Another way of saying that is to say, well, there
are differences in DNA that are associated with intelligence. We
knew that was true, and so a lot of modern
snip finding, from my point of view, is a matter
of confirming what we already knew. It's finding out the
same things about heritability that we already knew from twins
(24:49):
and siblings and families. I think there's a tendency to
sometimes that, even now that people have gotten used to
the idea that behavior is broadly heritable, to make the
same mistake you were suggesting of thinking, wow, now that
we're finding out that there are actual little bits of
DNA that are associated with these behaviors, that must really
be fixing it. You know that we're really finding the
(25:12):
education genes or more and more commonly, the IQ genes here,
and I personally don't really think we are. I think
it's safe to say the jury is still out And
I think there are a lot of people who think
that at least we're at the beginning of a road
that's going to end up with a actual genetic biological
understanding of something like educational attainment. I myself am quite
(25:36):
a bit more skeptical. But you would never you could
never do without the socialization process in this no matter
what is found. If you want to increase educational team.
Even if it turns out that some people have greater
genetic potential for the ultimate heights of learning and rate
of learning, et cetera, et cetera, that still doesn't mean
(25:57):
that we should provide the most challenging opportun coortunities for everyone, right, Oh,
of course not so. I think that kind of gets
missed sometimes in these discussions. Is you know, we can
get so lost in the weeds that so like so
what you know, like, you know, what's the practical implication here? Now,
some people have written some thoughtful books about a genetic
understand how genetically informed understanding of school could lead us
(26:21):
to teach an individualized learning for different people, et cetera,
et cetera. And I think there are some thoughtful things
out there about that, but still doesn't get rid of
the teaching part. No, of course not. I know you say,
of course not, but I do think that is missed
in somebody's well yes, no, and no. I mean I say,
of course not by way of agreeing with you. But
it it's an incredibly difficult and complicated problem. I mean,
(26:44):
I've spent my entire professional life trying to think about
exactly what it means that our genes might be related
to how much education people wind up obtaining. And you know,
if you put me on the spot and say, okay,
you've got three minutes explain exactly how that works, I'm
(27:06):
not sure I could do it. And it's a very
very deep and difficult theoretical problem. When you have a
problem like that, I think what happens is that the
two poles of the problem, the two easy ends of it,
become magnets for people. And you find people saying, oh, yeah,
we got the genes, you know, and people are just
(27:27):
born that way, and some people are born smarter than others.
And then you have people on the other side saying,
how could you say such a thing that the genes
have something to do with educational attainment, That that's determinism
and et cetera, et cetera, et cetera, and want to
argue that genes must have nothing to do with it,
and neither of those two polls is ever a good
(27:49):
answer good. I would not want it to be the
case that our intelligence was one hundred percent determined by
either the environment or one hundred percent determined by our genes.
Either situation would really suck if you think about it, right,
I mean, then you would have no free will either way.
Kind of. But people don't realize is that the way
the reality of the world is is actually pretty neat
(28:11):
in a way. There is something that it means to
be you, but there's also a lot that you can
do to construct yourself and become who you consciously want
to be. And also, I want to say I abhore
the process of the idea that someday we'll be able to,
as early as possible, measure people's genes and then use
that as a forecasting utility value to differentiate people into
(28:33):
different tracks as early as possible based on their genetics. Now,
I really really do not advocate for that. I agree
with you, Yeah, not just from like a there's a
moral standpoint, but just from like a human potential standpoint.
I'm not convinced that doing that would maximize Yeah, it
would be. I mean, the fact is people think of
it as something we could do off in some science
(28:55):
fiction future. But the fact is we could do it today.
About how we could do it today shows I think
why it's morally wrong. Here's how you predict kids' school
performance from their genes. You look up their parents' IQ scores,
and parents' IQ scores are really powerful predictors of children's
(29:16):
IQ scores. I mean really much much, much better than
anything we could do with genomic information. And much of
the reason for why parents IQ scores predict kid's IQ
scores are genetic. So why not just say, well, we
should take parents who are really smart and give best
resources to their children because they have the best genetic potential.
(29:39):
You can't do that because people have a right to
make the best of what they are, regardless of your
judgment of what their genetic potential is. I couldn't agree more.
Maybe I don't know if this is plain Devil's out
it be kid a little bit, But I want to
ask you a question I just thought of. So if
we agreed that the inhritability coefficient of a pt or population.
(30:00):
And by the way, heartability is a population variable related variable,
and it has to do with individual differences. There's no
other thing as a heritability within a person, just like
there's such a thing as a cube within a person.
And it also means that for me, the question what's
the heritability of intelligence is a really bad question. Intelligence
doesn't have a erritability. It's like a property of it
(30:24):
that it carries around from place to place. The heritability
of intelligence depends on the particulars of the situation in
which of the population in which that intelligence is measured. Absolutely,
so that's one part of it. But so if we
can agree that heritability is not a good proxy for
the ability to change, then you've shown done research interests,
(30:47):
a very interesting research showing that heritability coefficients are not
the same magnitude across social classes. Now, even if that
is true, and I'm kind of playing table's advocate for
a second, Even if that is true, and we already
just concluded that ritable is not a proxy for the
ability to change, then what's even the practical implication of
your own findings in that regard? Do you know what
I'm saying, yes, it's funny. I mean, if I'm honest
(31:09):
as somebody who's sometimes critical of people obsessing about what
the heritability of this or that is, I do think
it's hard to say exactly what it means that the
heritability of intelligence, which is what that research is about,
is different in some places than others. But I do
think you can put meat on the bones of that finding.
(31:30):
And the finding is that the heritability of intelligence, and
I should add it seems like it's in the United
States is lower in poor people than it is in
well off people, middle class and better people. Doesn't seem
like that happens in Europe, which is the main other
place that's been studied, probably because there's less economic and
equality there, and especially educational inequality. And I frankly can't
(31:54):
prove this. I think this is informed speculation about what
that might mean. A variant on a standard example for
thinking about genetic differences. I suppose you have a bunch
of seeds that are vary genetically for how tall plants
are going to be, and you plant them in really
excellent soil, and some plants wind up taller than others,
(32:17):
and that they're all in the same soil, the same
good soil, and some wind up taller than others, and
that's genetic variation in the seeds. You then take the
same handful of seeds or another handful out of the
same population and plant them in sand. Well, two things
are going to happen. First of all, they're all going
to be shorter, we all know that. But they're also
(32:38):
going to be less varied because they're all going to
be stunted. Even the seeds that had the genetic potential
to produce tall plants in the good soil are going
to wind up stunted. And of course if the soil
is bad enough, they're not going to grow at all.
So it makes sense that individuals need a reasonably supportive
(32:59):
and vironment in order to express their genetic variability. And
if people are in an environment that doesn't permit them
to seek out the environments that they can use to support,
as you said, who they're going to become, well, then
that's going to cut down on the variability. And with
(33:20):
heritability as a way of describing variability, so you know,
I think that's what's going on. Then you can take
a kid who has the potential to be a genius
and raise that kid in an environment with a different
family and crummy schools and a terrible neighborhood, and that
(33:41):
kid is not going to be able to find the
resources to help him or her become really, really smart.
And so it's a leveler. I say the rest of
this podcast, let's talk about the most controversial topics, because
I think that's it feels right to transition into those now.
So when we talk about sees the cause of SES
differences in this idea, you know, Charles Murray has the
(34:04):
CTD of the cognitive elite as kind of being a reason. Now,
it's a reasonable thing to say that there are IQ
differences between different SES groups. Just to say that is reasonable,
But to me, it seems to ignore all the you know,
it kind of puts too much focus on this one variable,
you know, when there are so many other variable one
(34:27):
could pick any one variable and write a whole book
of assigned the key causal role to that barrier. It
doesn't see intelligence as part of the network of good
things that happen to people when they're in a successful
society and have resources. It sees them as the cause
(34:50):
for why they're in that position. In the first place.
And you know, it brings us back to just everything
we were talking about the beginning. That g is this
property that exists inside people and causes them to express
all those good things that happen to them. That's the
Bell curve basically. And like you say, I mean, it's
not a I don't think that's a crazy idea or
(35:12):
a evil idea particularly. I just think it's wrong. I
just think it mischaracterizes the role that intelligence actually plays
in life. It's not the inner causal agent that causes
any more than health is to say. You know, like
you say, you could talk about there's a health elite, right,
not even health. We could add to this list any trait.
We could say aggression. Let's take aggression. I've seen some
(35:35):
fabulous research come out recently by Daniel Nettell and others
from an evolutionary point of you're showing just minor social
economic changes you make that reduce the aggression level significantly.
Now in some studies, I've seen their aggresion levels produced
so much that there's no difference anymore between well SS
and high SS. Once you make some minor system wide
(35:55):
tweaks to a really unstable and harsh environment, that people
are living in. So one could make argument they are
the way they are because they have low impulsivity, because
they have aggression. But if you instead view it as
the smaller we're talking about as these are all outcome
indicators kind of barometer, a barometer of what environmental experiences
interacting with genes that we all have, that any of
(36:17):
us could become in a way with certain environment Christians,
that's a different way of thinking about it, right, Yeah,
it's a much more complex way of thinking about it,
and it doesn't locate all the causation in one particular variable.
So let's go to the most controversial topic. Let's go
right there. Okay, race differences in IQ. Now, look again,
(36:41):
it is not an unreasonable thing to say that there
are race differences in average IQ scores between whites and blacks.
That's just an observation fact. And that gap does not
seemed to narrow in the past twenty five years. Okay,
I narrowed a little bit. It's not a topic I'm
an expert on, but some of my common co authors,
(37:02):
Jim Plann, dick nisbet Bill Dickens, who know more about
that than I do, I think, argue very persuasively that
it's down by a third over the last thirty four years. Okay,
so it's down, but there's still exists. Way, it hasn't
gone away. Okay, now there, and then there's the other question,
what are the causal forces? Just we have the same
(37:23):
discussion about sees Lyell and let's you know, we could
talk about group. Okay. The thing about this issue is
that Okay, so first of all, we know that just
because IQ is heritable, there's nothing in what we learn
about the hritle bit of IQ that can be directly
applied to understanding whether or not genes explain the difference
between blacks and whites. So we can have a whole
(37:45):
discussion as we are having on this podcast, agreeing that yes,
there is a genetic contribution to individual differences in IQ
in the general population, and that doesn't have anything to
say about whether or not to the extent to which
genes explain differences between different groups. Now, do are we
grid in that as well? Absolutely? So here's a question
I have is racist social construction. Does it make sense
(38:08):
even in the first place, to look for genetic environmental
factors that explain difference between whites and blacks in America. Well,
I mean, I'm not sure I have the same You
ask two questions, and I'm not sure I have the
same answer to both of them. The first one is
race to social construction, and the second doesn't make sense
to talk about genetic environmental great point, because one could
(38:29):
be yes, the other one can be right yes as well.
I'm a moderate sort of on that whole social construction business.
And in some funny way, that's a question that people
have argued about for so long, and it doesn't really
seem very complicated to me. In a way. There are
a lot of things that we know are true. The
human evolutionary story is a real thing, and we know
(38:52):
a lot about where human beings came from and how
they came out of Africa and how they spread around
the globe over a very very long evolutionary time span.
It's also the case that in more recent times, people
who live together in certain parts of the world are
more genetically related to each other. People who live in
(39:12):
Lithuania and think of themselves as Lithuanians are more like
each other than they are like Japanese people who are
like each other, and so it's not like the difference
between Japanese people and Lithuanians. Is this imaginary social thing
that we made up. There's biological reality, but the evolutionary
(39:34):
story and the geographical sorting of people around the world
is by and large continuous and dynamic. There aren't bright
lines dividing groups of people Lithuanians from Slovs. From those
lines that we impose on that biological reality are yes,
(39:57):
socially constructed. Now does that make them wrong? No? Does
it make them useless? No? It makes them artificial boundaries
that we impose on a very complex biological reality. So
one more example, just to make the point that I
was just thinking about. It's a kind of a trivial example,
(40:19):
but I think it gets the point. Ski slopes are
very complicated things. They differ in slope, they differ in
how many moguls they have, they differ in how long
they are, they differ in how narrow they are, all
sorts of things, and there are all sorts of ways
we could think about the difficulty of ski slopes. But
what do we do. We come up with yellow, blue,
and black, and we classify ski slopes as though there
(40:43):
were just three kinds yellow, blue and black. Now, if
we ask, are there really three kinds of ski slopes
in the world and only three kinds of ski slopes?
Of course not right. Ski slopes are much more complicated
than that. But sometimes under some circumstances, it's useful to
break them up in these those groups, as long as
we remember that the three part and the exact borderline
(41:07):
between yellow and blue is not given by nature. That's
something that we do. So that's the answer to that
A too long answer to the is it a social
construction question? Should I go on to looking for intelligence difference? No,
because I want to talk about the nittigree of this
now again. I refer people for a really nuanced review
of the current state of evidence. I refer people to
(41:29):
read Nicholas mcintosha's second edition of IQ and Human Intelligence.
He's a whole chapter on this, and I was say,
in a nutshell, after reviewing carefully all the evidence, there
is no good evidence that genes whatsoever play a role
in explaining differences between blacks and whites. The perspective I'm
coming from is, you know, education is such a crucial
(41:52):
gateway to opportunities in life. When I see the evidence
that blacks and whites differ on average in educational attainment
standardized test scores. Things like this, I immediately go into
like intervention mode, like I want to know, like what
are the whole causal factors? What are the things we
can do to change the culture, perhaps in some ways
(42:12):
to motivate show people who are in low sees environments,
for those who are difficult circumstances, that there's a future
for them. And all these factors have been shown to
help reduce the gap, little by little, lots of little
factors add up. Now the question is, even if they
don't all add up one hundred percent? To explain the differences,
I have this so what question? And Charles Murray was
(42:32):
recently on the Sam Harris podcast As You Know, and
Sam Harris asked him, you know, the so what question?
And the only answer Charles Murray had to the purpose
of finding out detaining the genetic information was implications for
college entrants for you know, And I don't feel like
I understood whatsoever. I still left that podcast not understanding
(42:53):
the so what question? Can you convince me at all
that there's any practically meaningful societal other than just knowledge
for the sake of knowledge of knowing that even like
five percent of the differences between different groups can be
not one hundred percent deterministic but are influenced by gene differences.
I have, again, I've complicated feelings about this. I'm I'm
(43:16):
not one who would think that there's ever a valid
scientific reality out there that we shouldn't go to because
the consequences are bad and we don't see the utility.
I mean, And in addition, as a practical matter, I
think it's generally impossible to keep those genies in the
(43:36):
bottle anyway. And if it's true and real, sooner or
later it's going to out and everybody's going to know
it anyway. So and I guess I do think that
for something that is on a sound theoretical footing and
has real meaning and it's true, we should go there.
And so I actually don't like the defense against genetically
(44:00):
based race differences, which says this is a bad thing there,
nothing good can come of it. Why should we know it?
I mean, if it were true and if it made sense,
and I don't think it makes sense, it's going to
happen anyway. By the way, I agree, I don't think
that knowledge should be censored and I encourage more research
on whatever someone wants to research. So I want to
(44:20):
be very clear about that. My question, the so what
question I'm asking is not the so what in terms
of like we shouldn't be doing the research. It's like,
you know, the so what is like I've been asking
so what a lot today, Like when we talked about
the fact that i Q might be heritable, Well, how
does that help me, as an individual think about what
is possible within me? So my question is people act
(44:41):
as though it'd be so forbidden if we found that
some small proportion of race differences was correlated with genetic differences.
But I'm trying to say, is even if we gosh
forbid found that, would that change change? I think would
be really bad. Frankly, tell me more, because what would it?
I mean again, I ultimately don't think this concept of
(45:01):
genetically based differences between groups makes any sense, and it
makes me nervous about talking about the consequences as though
it did make sense. But if we really knew that
an entire group, the only thing I can imagine that
meaning that statement meaning is that this group of people
has lower IQ than that group of people, and there's
nothing you can do about it. That's not what that
(45:22):
would mean, right, Well, I think would If it doesn't
mean that, then what sense does it make to say
that the mean difference is based in the genes, right,
If you can make it go way environmentally, then it
wasn't based in the genes in the first place. We
really don't know that because of the genes an individual
has that there's a limitation to what their IQ could
(45:44):
be under any possible environment that we could expose them to.
We don't know that short of them having some major
genetic disorder or something. And actually, I think that's a
very important idea that it's very important that we know
basically at asolutely nothing about the biology of why some
people are smarter than others from a genetic point of view,
(46:07):
because that really means that, as a matter of potential,
our malleability is practically unlimited. And it brings us back
to your original point that knowing that intelligence is heritable
does not put a limit on the malleability of that intelligence. Right. So,
(46:28):
if what you said is true that the heritability of
IQ is independent of the malleability of IQ, it's not
the case that printing out my genome when I was born,
gives you information that allows you to say that it's
impossible that the world might have turned me into a
(46:52):
Nobel Prize winner much smarter than I actually am. And
what we know about group differences in intelligence is that
the magnitude of them is smaller than we absolutely know
the malleability of intelligence to be in a number of ways,
that when children are adopted out of poor homes into
(47:15):
well off homes, the amount of change in their IQs
is larger than the modern difference between blacks and whites.
The difference in the average iq of white people in
the United States now and white people in the United
States in nineteen fifty is larger than the difference between
(47:36):
blacks and whites. So that we know, we know that
average IQs are malleable well within the range of that difference.
So knowing that, I simply don't see how it makes sense.
And you know, and when you were talking before about
mining to turnout, well that it's just a few percent,
just five percent, the whole percent thing, which is problematic
(47:58):
enough at the individual level, it makes no sense at
all at the group level. There is no group heritability
coefficient that can come out to be equal to a
particular number. If you go look at the articles the
very by the people who really believe in genetic differences
between the races, and in their own way take a
(48:19):
very scholarly and serious approach to the problem. It's not
like they're listing studies and saying this one shows that
it's twelve percent heritable, and this one shows that it's
twenty eight percent heritable. Because there's no mathematical model to
produce those numbers, the idea of the group difference being
x percent heritable doesn't make sense in terms, there's no
(48:40):
quantitative genetics that produces those numbers. One more and then
I'll stop, because I think this is the key important idea.
You know, if it made sense that groups might differ
in complex behavior, that the groups like different complex behavior
in a way that's partially in some percentage, wouldn't it
be the case that there were other group differences in
(49:01):
behavior that we'd already figured out. You know that Japanese
people are more introverted than people from the Dominican Republic.
Oh yes, and we've done some research and it turns
out that's genetic. On the other hand, you know, Chinese
people are better table tennis players than people from Kenya,
And hey, how do you like that we did the
(49:22):
research and that turns out to be environmental? Right, there's
not a single complex human trait that has ever been
shown to be genetic or environmental in any proportion, because
to me, it's not really an empirical question. The empirical
question is how malleable are these things? And to the
extent we know they're malleable, and things are way more
(49:43):
malleable than we think, to the extent they're malleable, we
can't prove that they're fixed genetically. Eric, I love that point.
I want to end on the point that the idea
of how niable things is a separate issue. I think
that's a theme of this whole discussion today, separate issue
from what's the herod ability? Explit good? And I want
to leave for the last thirty seconds on a very
(50:04):
personal note. I don't want to belabor it, but I
would be remiss not to say that I personally saw
what it was like to grow up with people expecting
very low things from you because of your IQ score,
because of a learning disability and auditory learning disability. I
had a very low measured IQ and that really I
was labeled a slow learner, and it really did affect
(50:25):
how people looked at me and treated me, and then
it affected my own self esteem and then what I did.
And it took a couple of people to really believe
in me and kind of look past the labels before
I was inspired to see what I was capable of achieving.
So I want to just say that some of these
researchers might want to spend some time digging more into
different perspectives. I look forward to reading your book. It
(50:45):
looks fascinating. Thank you so much for such an interesting
chat today. Okay, good, that was a pleasure. Thanks very much.
Thank you for the chat. Have a good day. Okay, yep,
I'll be in touch. Bye bye. Thanks for listening to
The Psychology Podcast with doctor Scott barrk Kaufman. I hope
you found this episode just as thought per booking and
interesting as I did. If you'd like to read the
show notes for this episode or hear past episodes, you
(51:07):
can visit the Psychology Podcast dot com.
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