July 26, 2022 • 46 mins
We humans are smart, to be sure, but if we’re so smart then how come we can’t figure how we got so smart in the first place? Think about that! We sure did and we go over some theories in this super interesting episode.
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Speaker 1 (00:01):
Welcome to Stuff you should know, a production of I
Heart Radio. Hey, and welcome to the podcast. I'm Josh,
and there's Chuck and Jerry's here too, and this is
stuff you should know, the brainiac condition. That's right. I
(00:23):
was trying to think of something and I was truly blank.
That's uh, that's how appropriate. It totally Chuck, because we
are talking today about human intelligence in the origin of
human intelligence, and it just seems super stuff you should
know me for us to not be able to come
up with a decent joke, you know, well Ed did
that for us, actually, because I did want to shut out.
(00:45):
We usually don't mention like section titles and stuff like
that that's actually in our notes, but Ed drops because
it's you know, it's for our eyes. But Ed dropped
to Simpson's reference in his section title one of the
great Simpsons references chimpan A to Chimpanzee was so great.
(01:05):
That was from the Planet of the Apes musical, right,
that's right. And I just I like to think is
that as a little gift from Ed to us? Yeah,
it definitely was, and it was well received too, So
thanks ed Um and the reason Ed created a section
called chimpaneze to chimpanzees because we're gonna talk about the
lineage of humanity like where humans came from UM And
(01:28):
despite that hilarious and clever um section title, we did
not actually evolve from chimpanzees, but we do share a
common ancestor from chimpanzee. So chimps and humans split off
from a shared ancestor about six to eight million years
ago UM, and that really kicked off a long line,
(01:48):
very long process um of evolution where intelligence started to
develop fairly early on. It just was really slow to start,
and then over time it kind of picked up speed. Yeah,
you found this some kind of cool statistic. There's a
researcher writer named Richard Leakey and H Richard, and I
(02:12):
think most people agree. They posit that there was what's
called a big bang of human culture around the Upper
Paleolithic time period where things were, like you said, slow
going for so long, and things were measured in in
eras before that, very very slowly over like hundreds of millennia,
(02:35):
and then all of a sudden, like sixty two thirty
thousand years ago or so, things started to really ramp
up in terms of innovation and intelligence. And uh, just
really moving the ball forward to use a football metaphor,
and we're talking about you know, clothing and uh, social
(02:56):
structure and in art and creativity and stuff like that.
So it's kind of cool to think, and you know,
we're going to talk about why that might have happened,
but uh, the fact that that did happen got us
on the moon in short order over the last few
thousand years. It's kind of like if you look at
the development of intelligence as a train that's starting from
(03:16):
a stop, it starts out with kind of a chuck
good chug good chug chug chugga chug a chuga, and
then that um, that Upper Paleolithic Revolution, the big bang
of culture. That's the cho choo part that really punctuates
the whole thing. I was thinking more along the lines
of it like a Japanese bullet train. But sure, I
(03:38):
don't think we're OK. We still do some really stupid stuff.
So we can also create a bullet train. We can,
but we just can't be the bullet train intellectual. Oh man,
mind blown. So chuck. The fact that thirty to sixty
thousand years ago there was that Upper Paleolithic Revolution where
humanity just suddenly blossom into what we recognize today as humanity.
(04:03):
It's really tempting to think that human intelligence just was
suddenly born all of a sudden, like geologically speaking, overnight
at that time. But that's just not the case. Um.
It seems like something definitely happened there, like some wire
connected with another wire that really made a big difference.
(04:23):
But instead, again, it was this part of this very
long line of seemingly random and unconnected um developments in
the in the history of humanity. And I guess our
our genus Homo um that led to that point and
actually led to that point today, because we're still evolving
and developing. Yeah, I guess uh. If you look at
(04:46):
it on a timeline, it looks like a mechanic came
along and said, well, here's your problem. You forgot to
plug you forgot to plug it in. That's right, you
gotta plug these two wires together and then you're all
set totally. But we like to talk about Homo sapiens
in in terms of human intelligence for good reason. Homo sapiens,
(05:10):
that is to say, us a k a. Modern humans
evolved about three hundred thousand years ago, um. But we
are just one of a collection of uh in in
this big lovely family called the Hominem's yeah, cominens comin
in Yeah, I think it's at ms. Yeah. So the
(05:30):
hominins are everybody that um that started off branching from
that common ancestor with chimps. That's the hominin line, and
humans in our genus Homo that Homo sapiens are a
part of, is just part of that hominin. There are
other entirely different genus or genie i that make up
the hominin line, right, that's right, And we should point
(05:52):
out that sapiens actually is taken from the Latin word
for knowledge, so it kind of all makes sense. It does.
So the whole thing starts out it seems like as
far back because we can tell um something again, like
somewhere around six or so million years ago, there was
a group of homonyms called Artipithecus um who basically walked upright.
But that was essentially the big difference between them and chimpanzees.
(06:16):
But as we'll see, that was a really really big difference, right, Yeah,
I mean we'll we'll get into this in more detail,
but obviously if you're walking up right, then you have
a very important thing at your disposal, which is use
of your hands. Right, So then, um, you've got Australopithecus uh,
and some a few other different kinds of branches that
(06:36):
kind of branch off. It's a really tangled, convoluted family tree, um,
where some kind of lead to blind alleys, others lead
to others. But um, they think that Australopithecus is was
a really big, long lasting group that was a little
more human, definitely more human than art Epithecus um, but
not quite as human as the genus Homo um, which
(07:00):
off all of these different species of human Because we're
we're alive today, we're on you know, planet Earth, living
here in two and every single human alive is a
member of the same species. So like there's different kinds
of cats, there's different kinds of fish species, there's different
kinds of bird species. Um, there's only one kind of
human species. But that wasn't always the case. There are
(07:22):
plenty of different human species, some living alongside one another
for tens or hundreds of thousands of years, that's right.
And almost all the hominins used tools, it seems like,
and make made tools, and for a long time we
thought that that was sort of it, that only the
Homo genus was the one who did use tools, which
(07:43):
is and you know, we talk about things like being
bipedal and using tools as sort of some of the
building blocks of what would become human intelligence. But now
we know that there are uh some older you know,
we found evidence that they use tools before that. Uh
that's kind of fairly recently, right, Yeah. We we wanted
to say that toolmaking started sometime after the Homo genus
(08:07):
showed up of a couple million years ago, um, but
we found even older tools. So it seems like austral Epithecus,
which again their hominance, they're part of the branch that
led to us humans, but they're not human in any way,
shape or form um. So the fact that they're using
tools was kind of mind blowing, and it also really
kind of undermined kind of like what you were saying,
(08:29):
like our idea of using tools, like that's a big
sign of intelligence, and and humans are intelligent, so it's
weird to find out that non humans were using tools
millions of years ago. That's right. Um, should we move
on to the hardware software thing? Yeah, So if if
tools and fire are not, um, because we found use
(08:50):
of fire dating back at least a million years. UM.
So if if tools fire hanging out with one another collectively,
if these aren't like the indicators that make human intelligence,
we've got to like get a little more granular. Unfortunately
for you and I sitting here today, chuck, UM, scientists
have done that, and they've come up with some really
interesting like ways of looking at this. Yeah, and UM,
(09:14):
there's a bit more of a preamble before we get
actually to the intelligence. UM. And I like the way
ed put this, sort of like talking about hardware versus software. Um,
they were very intertwined and um, you know, sort of
happening at the same time. So it's not like one
couldn't happen without the other as far as the hardware
software thing goes. But Uh, if we're looking at hardware
(09:38):
and we're talking about um changes that made us like
better at walking up right, Like you can you all
of a sudden just don't stand up and start walking
like this happens over a long long period of time.
Our hind legs got longer, Uh, the shape of our
pelvis changed. Um. There's something called the Foreman magnum, which
is a hole in the base of the skull where
(09:59):
the spinal cord and lots of nerves and things passed
like sort of open up those neural pathways, and that
changed its location. So these literal physical changes are happening
over great periods of time in order just to be
able to walk up right right and and bipedalism it's
like the defining characteristic of prominence. Right. There's there's not really,
(10:21):
as far as I can tell, any other animals that
that walk upright like by default. Um, so there had
to be physiological changes, but they're not entirely certain why
we started walking up right. But the fact that we
did and it's lasted for this long means that there
was some advantage to it because enough people walking upright
were able to pass along their genes. And they think
(10:43):
one one big theory is that it helped us survive
climate change where maybe things got colder and there were
less trees. So since we weren't arboreal anymore, we didn't
hang out and live and eating trees. We were able
to kind of move around and find different like food
sources in different shelters, whereas the like our cousins the chimps,
were in big trouble. They were up the proverbial creek. Yeah,
(11:07):
and I love that you point out that we, uh,
we're the only ones who walk upright by default, because
I think we can all agree there's nothing more fun
than YouTube videos of like a dog or a cat
or something just walking on its hind legs for some reason. Definitely,
and and it's the coolest and most fun thing ever.
It totally is. And I mean, now I'll take like
a Jesus lizard running across some water once in a
(11:29):
while too. There's nothing wrong with watching. Is that what
those are called? Yeah? I think I saw one of
those in Mexico, but that was surprising. Are they not there?
I don't know. I'm just saying I've I've never seen
one in real life, so I'm sure that was surprising
to see. I saw a lizard that was walking, and
it wasn't walking on water, but I think it was
(11:50):
one of those kinds that can I just didn't know
the name of it. Had you recently eaten the worm
from the bottom of the bottom of most cow? Very funny.
Another thing we should point out is that walking upright
is an energy saver. I mean, it's they've done studies
and they found that um, you use about the energy
(12:11):
um rather than you know, bounding around on all fours
like a chimp mte right or like a chimp does.
But to save that energy, to conserve it um, our
pelvis has had to change shape. Like you mentioned, that
was just a consequence of walking upright. Um. And the
reason to change shape is when you walk up right,
if you're a chimp, your body swings side to side.
(12:32):
You have to hold your arms up to balance yourself.
That takes a lot of energy. UM. So we developed
like gluteal muscles and other muscles that can cling to
a specific shaped in size pelvis so that we don't
have to spend all the energy. Our muscles are just
kind of keeping us much more balanced. But one of
the consequences of that of walking upright and our pelvis
(12:54):
changing means that the size of the birth canal afforded
by the hole in the all of us the child
passes through during birth. UM got smaller, a lot smaller.
And it's really strange to think that this the the
decreasing in size of the birth canal actually was one
(13:14):
of the factors that led to an increase in intelligence. Yeah,
and you know, we should point out this is just
the first of what will be a lovely cascade of
theories that we're gonna lay lay on your brains today. Uh,
and that, like you said earlier, there there is no one,
single one. It's kind of when you put all of
this stuff together. I think that's sort of the beauty
(13:35):
of of human intelligence, is it took all of these
great things sort of coalescing um. But the whole thing
with the brain is interesting because the size of the
brain is is one of nature's kind of controversies. Like
we know that as far as humans go, just because
you have a bigger brain doesn't mean that you definitely
(13:56):
will be smarter. But there are some correlations cross species
in nature, uh, and in humans there can be, you know,
evidence that bigger brain means you're more intelligent. But it's
not one of those things where it settles science where
they just say, hey, if you've got a bigger brain,
you're gonna be smarter. No, And in fact, like there's
all sorts of evidence in nature that suggests that's not
(14:18):
the case. Because our brain to body size ratio among
humans is one to forty, So our brain makes up
about our body mass, and that's the same ratio that
a mouse has. My mice just I don't care how
you cut it. They're just not as intelligent as humans.
But on the other hand, an elephants brain to body
(14:38):
ratio is one to five hundred and sixty and elephants
are super smart. So, um, you you can't really find
much there that says, you know, there's no direct correlation
where it's like the bigger the brain, the more intelligent
the being. Um. But there does have to be some
minimum amount of brain size because it seems like the
(15:02):
connections of the brain is we'll see, are what really matter.
And the more brain tissue you have up to a
certain point, the more connections that can be made. Right,
So that brings us back to the birth canal situation.
Like you mentioned you're walking upright, that changes in the
shape of the pelvis, you have a much smaller birth
canal all of a sudden. So evolutionarily speaking, you might think, well,
(15:25):
does that mean we're going to have to have babies
with tiny, tiny little heads and therefore tiny tiny little
brains that may not be able to grow very fast
because it's enclosed in a skull that's sort of locked down,
but that didn't happen to us. What happened was we
have Fontanell's and we have this delayed fusing of the
(15:46):
skull kind of you know, closing for good, and so
it allows and it's you know, it's remarkable still to
think about this to me, but it allows that little
baby head to squish down to get through the birth canal,
and it through the vagina and out into the world
and stay that way for a while. And it's during
that for a while period before that skull completely fuses
(16:10):
that a human brain really really grows a lot, and
chimps don't have that ability. No, a chimp, uh, their
skull fuses mostly in the womb, and their brain, as
a consequence, grows mostly to what size it's going to
reach in the womb. So, on the one hand, a
chimp baby, you could say, is much smarter and much
(16:31):
less helpless than a human baby. But given enough time,
the human baby is going to start to exceed the
chimp's abilities very quickly. And it's because our development is delayed.
We do a lot of developing outside of the womb,
and that's afforded by that skull that's not fused. For
a couple of years after birth. And this was not
(16:52):
there is no intelligent design, so there this was not like, um,
like a good solution or work around. This was just
a natural selected, naturally selected trait, the skull not fusing.
That was a solution to the smaller birth canal, not
to not to increase intelligence, but the advent of babies
(17:15):
being born that didn't have few skulls allowed for the
advent of intelligence. Yeah, a solution to the problem of
walking up right, which is really interesting to think about. Yeah,
And it also just goes to show like it's like
nature is not always like elegantly simple. Sometimes it's really
convoluted and organisms including us are held together by like
(17:38):
duct tape and bubblegum, you know. And that's a good
example of it. I think that's a good time for
the break, yea, yea. And we'll come back and drop
some plasticity on your brain right after this, So, Chuck,
(18:13):
this is the point we're about to talk about brain plasticity.
This seems to be, uh, what if anything explains human intelligence,
and certainly the burst of intelligence that happened thirty to
sixty thou years ago. Yeah, And I think the opening
statement to this whole thing is all you gotta do
(18:33):
is look at the fact that we learn almost everything
as humans, like from the moment we're born. There there
is some maybe instinctive knowledge, but like you said, like
human babies are kind of helpless, little dumb dumbs. And
from that point forward, our brains are are learning and
(18:53):
they're growing, and they're capable of learning, and they're capable
of adapting. And this all has to do with plasticity, right, So,
just if you aren't familiar, plasticity is the brain's ability
to um basically rewire and create new connections as new
experiences come along. Uh, And you can even take old
(19:13):
experiences that you experience more than once and the second
and third and fourth time, those neural connections are going
to become more sophisticated and more connected than they were before.
So our brains are plastic. They can be molded and
shaped kind of like in the rhinoplastic um sense of
the word. They're not made of plastic. They can be
(19:33):
molded and they're molded by the connections that they make.
So it's not necessarily that you have a giant brain.
It's that you human being have a brain that is
really highly capable of creating new connections, and it's those
connections that forms the basis of intellect. Yeah, and that
really frees up, Like once you have a brain that's
(19:55):
plastic and that can evolve, you know, to figure out
a pro ablem rather than taking eons and eons to
have like genetic to genetically adapt to a solution to
a problem. If all of a sudden you have a
brain that can figure something out, you do it so
much quicker, and that frees you up to do more
and learn more, and it creates this feedback loop all
(20:18):
of a sudden where the process really really speeds up.
And that's you know, basically what we saw thirty sixty
years ago. Yeah, and the reason and we're still seeing
it today, Chuck. I mean, like you know, a thirty
to sixty thousand years ago, it was a huge burst
of creativity and intelligence, but we're still talking about changes
that took place over thousands of years. Now. We're seeing
(20:39):
changes to the human condition in our society that takes
place over like tens of years. So it still seems
to be speeding up and we're still going through the
same process. But the I guess the best way to
think about what you've just described as evolution, which typically
you know, UM forces changes on us based on environmental conditions,
(21:02):
goes into the brain, and now it's the brain that's
able to change, and like you said, it changes much faster,
and that leaves genetic evolution or genetic natural selection to
focus on UM selecting for traits that create more and
more intelligence. So it creates that positive feedback loop like
you said, and speeds things up. It's pretty brilliant. So
(21:23):
there's been a lot of really interesting research, especially in
that it seemed like the early to mid nineteen nineties
about plasticity UM. There are a couple of researchers name
to Be and Cosmides great names, and they had a
theory basically that human intelligence UH evolved with all these
UM encapsulated cognitive models, so they did not have the
(21:47):
ability to excess each other. Each each of these modules,
and each one was very specialized for a very specialized
problem or task that was trying to do our problem
that was trying to solve, and that's like a language module, UH,
spatial relation module. UH, here's how to make and use
a tool that kind of a module. And that all
(22:10):
these modules are still around, uh and basically the same
form that they were back then, because it's there on
the timeline of you know, humanity, that that hasn't been
a lot of time to undergo any kind of modifications basically,
So I disagree with that. I think I think on
a speaking about classic evolution natural selection, that's true, but
(22:33):
brain based evolution and natural selection like cultural natural selection,
I think that that's false. You hear that to be. So.
The the idea about all this is that these modules
that we developed over time is like we came upon
new problems in our environments and had to figure out
new solutions to them. They started to kind of get
(22:54):
cross referenced here there, Like you could say, um, you know,
the same the same ability to UM to to follow
the sunset, right, Yeah, I wish I would have come
up with something better can also can also be used
to UM to follow herds of game, right. And so
(23:16):
all of a sudden we now not only just know
to to follow the sunset if we want to follow
the sunset, we also know we can use that same
ability to follow game around. And all of a sudden,
our diet expands that kind of thing. So as these
different modules started cross referencing themselves and and got more
and more connected. We were able to apply these different
(23:36):
things to more and more situations and got more and
more intelligent. All right, So that's UM. That's one sort
of grand theory which I love. Another one that we're
going to talk about is I think super interesting because
some of this stuff is so kind of rudimentary in
it when you just sort of look at it from
(23:57):
a macro view, but when you really have to think
about how important that ended up being, it's it's fascinating
to me. And in this case, we're talking about the
fact that UM. One of the sort of side and
again it's going back to bipedalism. One of the side
effects bipedalism is that we lost our ability, UM, with
our feet to be able to like hang onto things
(24:20):
like chimpanzees do. They were these boots were all of
a sudden made for walking, and they weren't made for grabbing.
And if they weren't made for grabbing, then you couldn't
hang on to mama like a chimp could with hands
and feet. So mama had to hang on to human baby.
And mama can't hang on to human baby all the
time because mama still has to get things done around
(24:43):
the you know, savannah. So what you have to do
then is leave that baby somewhere and go do stuff
like go down to the river and uh and do
things and uh. If you leave a baby somewhere, what
you go down to the river and do and things?
Two things you know unen uh and if you leave
(25:05):
that baby And this is all leading to this statement,
if you leave that baby somewhere, you want to be
able to go back and find that baby. And it
seems so rudimentary and basic, but that is a huge
thing in the development of the early human brain, is
simply to spatially map and remember, like where I have
left this child. It's important to go back and get
(25:25):
that child, and I can do that. Yeah, and then um.
Consequently to that, another adaptation seems to have arisen from
the same problem, the problem of not being able to
cling to the mother anymore, and then also the problem
of the baby being otherwise helpless, way more helpless than
a baby chimp. Right, So they think that around the
(25:47):
same time baby's cries developed, like you don't hear other
things necessarily crying like a human baby, And they don't
think that babies cried like that until around this time,
because there was that problem. So even if a mom
couldn't remember where she put her baby, she could listen
out for the baby crying. And they also think around
this time that an urge or desire to soothe the
(26:09):
baby from its crying would have developed, and that it's possible, Chuck,
And this makes so much awesome sense that language actually
developed out of what's called mother ease, that kind of
soothing baby talk that calms the baby, that mothers know
how to do just naturally. They think that it's possible
that that is what formed the basis of language. Yeah,
(26:31):
and I'm gonna go beyond that even because what I
noticed when I had a baby in the house was that,
even beyond the soothing thing, if you are holding your
baby and you have to put your baby down to
go wash the dishes or whatever, generally, and I think
I speak for most parents, you don't just go set
your baby down, go in the other room and do stuff.
(26:52):
You're you're talking to that baby from the very beginning,
and you're saying, all right, let's go over to our
little place here. I'll be right back. I'm gonna be
right here in the other whom that baby doesn't know
what you're talking about, obviously, but there's there just seems
to be this evolutionary instinct to to say things to
it right out of the gate. It's really interesting. It
is interesting, and then wrapped up in this also there's
(27:14):
a better example than following the stupid sunset that I
came up with. I love sunsets. But if you can
now all of a sudden like remember where landmarks are
and then wayfind your your way back to you know,
the starting point. Now you can start to use that
to follow game further and further afield, and you're expanding
your range and you can expand your diet. So that's
(27:35):
a really good example of one thing kind of leading
to another, and all of it being um arising from
environmental pressers brought on by changes to buy of us. Yeah,
I love it me too. Um. This next one is
kind of fits in a little bit with a plasticity
I think. Uh. The idea of the cognitive niche um,
(27:59):
which is, you know, typically figuring out like a solution
to a problem. But this theory is that maybe intelligence
evolved as a universal adaptation to all kinds of uh,
evolutionary pressures that we're bearing down. So um and ed
has a pretty great example. If you've got a an
(28:19):
island with a tree that has a certain um fruit
seed that's really beneficial for your body, Um, but you
can't crack into it. There's you know, it would take
a bird, uh, you know, hundreds to thousands or millions
of years to develop and evolved to have a beak
that can crack that thing open. But if all of
(28:39):
a sudden, you know how to make a tool, you
can just walk over and steal that thing from that
dumb bird and just crack it open with the tool.
So it's not filling, it's your brain at work, and
in that case is filling a specific niche. But that's
a tool that was also used to kill the animal
or chop the wood. Yeah, and that really supports what
we were talking about a few minutes ago that once evolution,
(29:02):
once a brain is evolved to a certain amount of intellect,
the brain can take care of the organism and natural
selection and genetics can kind of take a step back
and not have to say, like, um, you know, uh,
select for a thicker harrier chest. Because we're living in
a colder time now because the brain can come up
(29:23):
with a way to create a coat, right, So it
just kind of takes over evolution from evolution by doing that,
and that's that cognitive niche. And one of the consequences
of it is that there seems to be as as
things change in our environment, we figure out new ways
to to solve those, and then those those solutions are
(29:47):
inevitably going to create other problems or changes, So then
we have to we have to evolve even further intelligence
to figure out how to solve these new problems. You
can actually see it still going on today, Chuck, Like,
we've evolved a level of intelligence where we can extract
petroleum from the earth, we can build machines that run
(30:08):
on that petroleum, and we can develop science that figures
out that burning those the that petroleum is really really
bad for the climate. So now we've we've altered our
ecosystem enough that we have to evolve intelligence enough to
figure out how to get out of this new conundrum
that we've created for ourselves based on our previous intellect.
(30:30):
So intellect builds on intellect through environmental pressures that we
often bring on ourselves. That seems like the case, Yeah,
I mean, I think a lot of people seem to
think of intelligence is only solving problems, but it also
creates a lot as well. It's interesting, Yeah, it really is. Um.
I know we were gonna skip this section entirely, but
(30:51):
I think just for frenzies, we should very quickly mention one,
uh the ideas from someone called Terence McKenna who describes
as a post modern Timothy Leary type, one of these
people that that advocates for psychedelic drug use, and just
very quickly the idea is that, uh, the cavemen were
(31:13):
tripping on mushrooms and that's how intelligence evolved. And I
just like mention it because I feel like there's almost nothing,
no leap in history that some person hasn't said, like
the Enlightenment or whatever, like, oh man, they were just tripping, right,
they were just super I don't think it's pretty funny.
(31:34):
It is funny, but it does. I mean, like if
you apply it exclusively to the Upper Paleolithic Revolution, where
all of a sudden there's like art and jewelry and
dancing that stuff, it's possible that it was based at
least in part you know, yeah, you never know, alright,
So I say, we take a break and we come
back and get down to the nitty gritty of how
(31:55):
food might have brought intelligence along. How about that? Mm hmm.
(32:19):
By the way, Chuck, I have a theory real quick
that the more you say uh or um, the more
intelligent you um are. Oh boy, I must be a
smarty pan. You know, other more intelligent podcasts cut all
that stuff out. Yeah, I guess do they? Yeah? I mean,
(32:40):
what did I mispronounced in the Row episode? I couldn't
even substantive Oh yeah, yeah, it's true. Other podcasts would
not have left that in. But that's because dummy leaves
that they're not as brave. We're courageous podcasters. Okay, I'll
buy that. Um. This next theory I think is super
cool because anytime each tie in um, not just food,
(33:04):
but sort of a an appreciation for a creature comfort,
it really like turns turns me on and not you know,
in certain ways intellectually turns me on. And in this case,
we're talking about the fact that we used fire obviously
and then started cooking food, and people that cooked food said, wow,
(33:30):
this is really good, and this taste a whole lot
better than that raw meat. We've been eating this charred
meat is delicious, and let's let's try and do more
of this around here. Yeah, And so that would have
just them being um, responding to like a taste preference,
and that's it. But it just so happened that that
(33:52):
taste preference would have had a really big benefit and
a big contribution to the development of intelligence. Because if
you cook me eat um, you unlock a bunch of
nutrients and calories that are otherwise unavailable to you if
you just eat it raw. So over time, the people
who ate meat would have had more energy and more
(34:12):
calories to contribute to a growing brain, which could have
helped the process along if not sped it up. And
if you consider the fact that we've definitely seen that
that taste and smell has responded to evolutionary pressures in
that we at some point learned not to eat poop,
and we learned not to eat rotten food and stuff. Um,
(34:33):
And that's you know, taste and smell it can have
the you know, it looks like it can have the
opposite effect to where all of a sudden you have
a preference for the good. And that just happens to
work out in your favor. Yeah, and this is another
example of one thing leading to another, where like you know,
mothers developed an awareness of landmarks and wayfinding, and then
that led to um being able to follow game, which
(34:55):
expanded our diet, which led to us eating meat, which
eventually led to applying controlled fire to that meat, which
led to more calories and nutrients available, which led to
bigger brain growth, which helped found uh, the growth of
intelligence and humans. Just one thing, one totally random, unconnected thing,
or even connected but seemingly unconnected, uh, just creating us today.
(35:20):
It's just so nuts. So to me, I love it. Yeah,
me too. And the fact that, like, think about this,
not only the preference for a charred meat, but the
preference for a specific charred meat because you know, different
stuff tastes different. It's not like everything tastes like chicken.
I know that's a joke, but all of a sudden
took took his out there and and says, boy, that
(35:42):
one thing that we killed yesterday. You guys, I don't
know about you, but that was really really delicious. And
we know that that is we saw that thing three
days ago, about fifty miles away. Everyone said, what's a
mile and he well, that doesn't matter right now, but
the point that it was really far away. So all
of a sudden, other things are introduced, like cooperation, not
(36:04):
just wayfinding, but hey, let's let's all get together because
this is like a three day journey and this thing
is really big. That tastes so delicious, So it's gonna
take a few of us to bring this thing down
and to process this animal and get this meat ready
for cooking. So it just introduces like a cascade and this,
and it could have all just come from Hey, that
(36:25):
tastes really great. Yeah, and so that that you know,
these all that hunting and coordinating all that takes like
a lot of intelligence. And not only does it take
intelligence to to coordinate, it takes intelligence to explain what
you're talking about. And it takes intelligence to come up
with that plan in the first place, you know. So
all of those factors combining are just making humans more
(36:48):
and more intelligent with every every step. And again, it's
not like it's just following this perfect linear progression. Yeah,
it's just like it's just kind of randomly. And the
the reason that we're intelligent today is because the attempts
that didn't work out, got selected out, the fact got
trimmed along the way. Is it kind of a ruthless
(37:09):
way to put it, but you know it makes sense. Uh.
And that sort of ties into this other theory of
um smaller prey, like when they were hunting um large
prey species that you know, they eventually uh, they were
hunting and track of these these large animals and eventually
they were driven to extinction. So humans had to start
(37:32):
going after smaller things or I guess, uh, hominem's had
to start going after smaller things, and the fossil record
indicates this. It sort of worked in lockstep with the
evolution of human intelligence. So all of a sudden, if
you're hunting smaller things, you probably have to be a
little bit smarter. You have to be a little bit
more coordinated, you have to cooperate a little more, you
(37:55):
have to maybe invent new tools, and like obviously using
a big thing to smash a large thing isn't the
same thing smashing a small thing. Uh. And just simply
the fact that they had to do a lot more
of it. You know, if you're eating a squirrel uh
as your diet, you're you're eating a lot of squirrel
every day, whereas if you eat a wooly mammoth, that's
your food for the month or whatever exactly. And that's
(38:17):
a really good example of what I was talking about earlier,
that cognitive niche where the more sophisticated we get, the
more problems we actually generate for ourselves, the more challenges,
the more intelligent we have to become. That's right. And
what about this last notion? And then I think this
is kind of where it all comes together, right, Yeah,
so you know, we have like a real urge and
(38:39):
a desire to to wrap everything up in a neat
little package, and we just haven't reached that point yet
with human intelligence. But if you step back and look
at some of the theories, um and see how they
all kind of fit together, it seems like most are.
All of them with the exception of stone date probably
could be right. But they all have to work together
(39:00):
and work with one another, um, which is great because
that level of organization requires intelligence, that's right. But the
key to all of this, and I think, um, we
we talked about the evolution of language on a whole show,
right yeah, uh, we we still don't quite know exactly
how that evolve, but we have some ideas, like we
talked about with the uh, what'd you call it? Mother
(39:23):
ins No, mother ease, mother ease. But all of this
became possible because of language. All of this, like you
were saying, all of this coordination, all this cooperation, anything
that would eventually lead to writing down human history, all
of that had to have language. So it seems that
all of these sort of theories coalescing around the beginnings
(39:45):
of language, and eventually the written word is like the
key to it all. Yeah, totally. And one of the
other things. Um, because we are so aware that we're
intellectually superior, not only to all the other animals, at
the very least, we're intellect really different from the other
smart ones. Um, we tend to think of ourselves as
the most intellectually evolved or the most successful humans ever,
(40:09):
and that's absolutely not the case. Um. I think Homo
erectus was around for one and a half million years
and modern humans have only been around for about three
hundred thousand years. So we're definitely not necessarily the pinnacle
of evolution just in the amount of time and success
we've had so far. But also, um, we have a
tendency to think like we're we're the top and there's
(40:31):
nothing coming. And that's not necessarily true either. Like if
you look at that acceleration and technology, like um, some
of our ancestors used the same tool for a million
and a half years without innovating upon it. They just
made that same tool over and over and over again.
And then somebody came along who was born and figured
out a way to make it better, and that kicked
(40:51):
off more and more technology, and you can see it's
picking up faster and faster. But the fact that evolution
has jumped from the external old for us to our
brains and in turn to our culture, you can make
a really good case that we're not necessarily going to
physically evolve any longer. We're going to mentally evolve. So
(41:11):
it's not it's not certain what humanity is going to
look like in the future, but it's probably going to happen.
The changes are going to happen a lot faster soon
than they have been before, and we'll all just end
up brains and jars right probably or uploaded. That's right.
Oh boy, good luck with that. Everybody that had a
(41:35):
very so long sucker bring to you, got anything else?
I got nothing else. I love these, uh that types
of episodes. Stuff me too. Since Chuck and I agreed
we'd love this episode, it's time for listener mail. So
this is another Appalachian trail probably the last one I'll
read because, Um, Sophie here a k A tough cookie,
(41:59):
which a Sophie's trail name. It's just a lovely human
and we we had a nice back and forth Sophie
and Sophie's sister did a nobo through hike inven and
just had some kind of fun things to point out. Um.
One of the general rules of trail names is someone
else has to give it to you. So I think
(42:20):
that's kind of like, uh, if you're a pilot in
the military, you're like a Maverick and Goose. I think
people think they name themselves cool names. But my brother
in law was like, no, no no, no, no, no, you'd
get a name, and it's usually not something super cool
like Maverick. Yeah, if you name yourself, I'm sure that
people are going to be way harder on you in
the name they actually select for you. Yeah. I don't
(42:41):
even know if you're allowed to. I'm not sure. Uh.
Sophie says that my sister and I cheated a little
bit because we gave names to each other a few
days in. I don't think that's cheating. You're still naming
someone else. Sure, that's called getting ahead of the curve. Uh.
We We did have some unofficial trail names though, that
other people would refer to the pair of us as.
My favorite was a sixty year old Kentucky hiker from
(43:02):
Maine who told us, uh, he referred to us as
the Kentucky Wonders, which is pretty fun. And one thing
I realized after reading all these A t emails is
that it's it's really kind of fun. Like people get
together and like they start off alone and all of
a sudden there's a group of like twelve people hiking
together for weeks at a time. That is the very
reason why I will never hike they that sounds like
(43:25):
a nightmare to me. You would be the uh, the
loner hiker totally. Maybe, like, don't turn your back on
that one. I think your trail name might be Jed Bundy. Um.
The trail through West Virginia is actually less than four
miles and I heard this from other people to um,
not eighteen. So I think we screwed that up. It's
(43:47):
an amazing feeling to go through so quickly after psychologically,
after completing Virginia, which is five hundred miles and a
quarter of the whole entire trail. Uh. And there is
a four state challenge that some hikers will attempt to
do a forty five mile day to go through the
end of Virginia, West Virginia, Maryland, and into Pennsylvania in
two hours. Her family hosts a trail magic spot because
(44:14):
they live near the trail in Tennessee, So they will
go out on the weekends and they pack up a
bunch of hiker food and they grill burgers and stuff
or make pancakes and just feed people on the trail
and then we'll go back home. I think you could
be down with that part, right. Sure, I'd need a
free hamburger, Like can I take it to go? I'd
be like why, I'd be like why is there mustard
(44:36):
on here? But not catch up? Uh. And then finally,
during the hike, we would treat ourselves to podcast for
a couple of hours when hiking was getting monotonous and
wanted to get out of our heads some and your
voices were a frequent, frequent companion listening to stuff that
you should know. Selects these days often have the weird
sensation of remembering exactly where I was hiking in the
woods when I listened to that episode. Uh, come to
(45:01):
Kentucky sometime, check out the Bourbon distilleries and the Red
River Gorge and do a show here Lexington. I know
you'd probably rather go to Louisville or Cincinnati, but Lexington
is definitely worth a visit. And Sophie sent along a
bunch of cool pictures of Sophie and her sister before
and after, and it's just looked like a really great time.
That's awesome. Thanks a lot for that email, Sophie, that
(45:22):
was a great one. And agreed Chuck that one had
to be right for sure. Just stay away from Josh
if you see him in the woods. No, I'm harmless.
I just don't want to be spoken to. That's all.
I want to be left alone. It's too awkward. Otherwise,
you could just hike with a big giant like nineteen
seventies headphones as if you're listening to right with my
(45:43):
head down, sunglasses on in a bag over my head.
I love it. If you want to be like Sophie
and get in touch with us. You can send us
an email and send it off heart Radio. For more
podcasts my heart Radio, visit the heart radio app. Apple
podcasts are ever you listen to your favorite shows. H
Welcome to Stuff you should know, a production of I
Heart Radio. Hey, and welcome to the podcast. I'm Josh,
and there's Chuck and Jerry's here too, and this is
stuff you should know, the brainiac condition. That's right. I
(00:23):
was trying to think of something and I was truly blank.
That's uh, that's how appropriate. It totally Chuck, because we
are talking today about human intelligence in the origin of
human intelligence, and it just seems super stuff you should
know me for us to not be able to come
up with a decent joke, you know, well Ed did
that for us, actually, because I did want to shut out.
(00:45):
We usually don't mention like section titles and stuff like
that that's actually in our notes, but Ed drops because
it's you know, it's for our eyes. But Ed dropped
to Simpson's reference in his section title one of the
great Simpsons references chimpan A to Chimpanzee was so great.
(01:05):
That was from the Planet of the Apes musical, right,
that's right. And I just I like to think is
that as a little gift from Ed to us? Yeah,
it definitely was, and it was well received too, So
thanks ed Um and the reason Ed created a section
called chimpaneze to chimpanzees because we're gonna talk about the
lineage of humanity like where humans came from UM And
(01:28):
despite that hilarious and clever um section title, we did
not actually evolve from chimpanzees, but we do share a
common ancestor from chimpanzee. So chimps and humans split off
from a shared ancestor about six to eight million years
ago UM, and that really kicked off a long line,
(01:48):
very long process um of evolution where intelligence started to
develop fairly early on. It just was really slow to start,
and then over time it kind of picked up speed. Yeah,
you found this some kind of cool statistic. There's a
researcher writer named Richard Leakey and H Richard, and I
(02:12):
think most people agree. They posit that there was what's
called a big bang of human culture around the Upper
Paleolithic time period where things were, like you said, slow
going for so long, and things were measured in in
eras before that, very very slowly over like hundreds of millennia,
(02:35):
and then all of a sudden, like sixty two thirty
thousand years ago or so, things started to really ramp
up in terms of innovation and intelligence. And uh, just
really moving the ball forward to use a football metaphor,
and we're talking about you know, clothing and uh, social
(02:56):
structure and in art and creativity and stuff like that.
So it's kind of cool to think, and you know,
we're going to talk about why that might have happened,
but uh, the fact that that did happen got us
on the moon in short order over the last few
thousand years. It's kind of like if you look at
the development of intelligence as a train that's starting from
(03:16):
a stop, it starts out with kind of a chuck
good chug good chug chug chugga chug a chuga, and
then that um, that Upper Paleolithic Revolution, the big bang
of culture. That's the cho choo part that really punctuates
the whole thing. I was thinking more along the lines
of it like a Japanese bullet train. But sure, I
(03:38):
don't think we're OK. We still do some really stupid stuff.
So we can also create a bullet train. We can,
but we just can't be the bullet train intellectual. Oh man,
mind blown. So chuck. The fact that thirty to sixty
thousand years ago there was that Upper Paleolithic Revolution where
humanity just suddenly blossom into what we recognize today as humanity.
(04:03):
It's really tempting to think that human intelligence just was
suddenly born all of a sudden, like geologically speaking, overnight
at that time. But that's just not the case. Um.
It seems like something definitely happened there, like some wire
connected with another wire that really made a big difference.
(04:23):
But instead, again, it was this part of this very
long line of seemingly random and unconnected um developments in
the in the history of humanity. And I guess our
our genus Homo um that led to that point and
actually led to that point today, because we're still evolving
and developing. Yeah, I guess uh. If you look at
(04:46):
it on a timeline, it looks like a mechanic came
along and said, well, here's your problem. You forgot to
plug you forgot to plug it in. That's right, you
gotta plug these two wires together and then you're all
set totally. But we like to talk about Homo sapiens
in in terms of human intelligence for good reason. Homo sapiens,
(05:10):
that is to say, us a k a. Modern humans
evolved about three hundred thousand years ago, um. But we
are just one of a collection of uh in in
this big lovely family called the Hominem's yeah, cominens comin
in Yeah, I think it's at ms. Yeah. So the
(05:30):
hominins are everybody that um that started off branching from
that common ancestor with chimps. That's the hominin line, and
humans in our genus Homo that Homo sapiens are a
part of, is just part of that hominin. There are
other entirely different genus or genie i that make up
the hominin line, right, that's right, And we should point
(05:52):
out that sapiens actually is taken from the Latin word
for knowledge, so it kind of all makes sense. It does.
So the whole thing starts out it seems like as
far back because we can tell um something again, like
somewhere around six or so million years ago, there was
a group of homonyms called Artipithecus um who basically walked upright.
But that was essentially the big difference between them and chimpanzees.
(06:16):
But as we'll see, that was a really really big difference, right, Yeah,
I mean we'll we'll get into this in more detail,
but obviously if you're walking up right, then you have
a very important thing at your disposal, which is use
of your hands. Right, So then, um, you've got Australopithecus uh,
and some a few other different kinds of branches that
(06:36):
kind of branch off. It's a really tangled, convoluted family tree, um,
where some kind of lead to blind alleys, others lead
to others. But um, they think that Australopithecus is was
a really big, long lasting group that was a little
more human, definitely more human than art Epithecus um, but
not quite as human as the genus Homo um, which
(07:00):
off all of these different species of human Because we're
we're alive today, we're on you know, planet Earth, living
here in two and every single human alive is a
member of the same species. So like there's different kinds
of cats, there's different kinds of fish species, there's different
kinds of bird species. Um, there's only one kind of
human species. But that wasn't always the case. There are
(07:22):
plenty of different human species, some living alongside one another
for tens or hundreds of thousands of years, that's right.
And almost all the hominins used tools, it seems like,
and make made tools, and for a long time we
thought that that was sort of it, that only the
Homo genus was the one who did use tools, which
(07:43):
is and you know, we talk about things like being
bipedal and using tools as sort of some of the
building blocks of what would become human intelligence. But now
we know that there are uh some older you know,
we found evidence that they use tools before that. Uh
that's kind of fairly recently, right, Yeah. We we wanted
to say that toolmaking started sometime after the Homo genus
(08:07):
showed up of a couple million years ago, um, but
we found even older tools. So it seems like austral Epithecus,
which again their hominance, they're part of the branch that
led to us humans, but they're not human in any way,
shape or form um. So the fact that they're using
tools was kind of mind blowing, and it also really
kind of undermined kind of like what you were saying,
(08:29):
like our idea of using tools, like that's a big
sign of intelligence, and and humans are intelligent, so it's
weird to find out that non humans were using tools
millions of years ago. That's right. Um, should we move
on to the hardware software thing? Yeah, So if if
tools and fire are not, um, because we found use
(08:50):
of fire dating back at least a million years. UM.
So if if tools fire hanging out with one another collectively,
if these aren't like the indicators that make human intelligence,
we've got to like get a little more granular. Unfortunately
for you and I sitting here today, chuck, UM, scientists
have done that, and they've come up with some really
interesting like ways of looking at this. Yeah, and UM,
(09:14):
there's a bit more of a preamble before we get
actually to the intelligence. UM. And I like the way
ed put this, sort of like talking about hardware versus software. Um,
they were very intertwined and um, you know, sort of
happening at the same time. So it's not like one
couldn't happen without the other as far as the hardware
software thing goes. But Uh, if we're looking at hardware
(09:38):
and we're talking about um changes that made us like
better at walking up right, Like you can you all
of a sudden just don't stand up and start walking
like this happens over a long long period of time.
Our hind legs got longer, Uh, the shape of our
pelvis changed. Um. There's something called the Foreman magnum, which
is a hole in the base of the skull where
(09:59):
the spinal cord and lots of nerves and things passed
like sort of open up those neural pathways, and that
changed its location. So these literal physical changes are happening
over great periods of time in order just to be
able to walk up right right and and bipedalism it's
like the defining characteristic of prominence. Right. There's there's not really,
(10:21):
as far as I can tell, any other animals that
that walk upright like by default. Um, so there had
to be physiological changes, but they're not entirely certain why
we started walking up right. But the fact that we
did and it's lasted for this long means that there
was some advantage to it because enough people walking upright
were able to pass along their genes. And they think
(10:43):
one one big theory is that it helped us survive
climate change where maybe things got colder and there were
less trees. So since we weren't arboreal anymore, we didn't
hang out and live and eating trees. We were able
to kind of move around and find different like food
sources in different shelters, whereas the like our cousins the chimps,
were in big trouble. They were up the proverbial creek. Yeah,
(11:07):
and I love that you point out that we, uh,
we're the only ones who walk upright by default, because
I think we can all agree there's nothing more fun
than YouTube videos of like a dog or a cat
or something just walking on its hind legs for some reason. Definitely,
and and it's the coolest and most fun thing ever.
It totally is. And I mean, now I'll take like
a Jesus lizard running across some water once in a
(11:29):
while too. There's nothing wrong with watching. Is that what
those are called? Yeah? I think I saw one of
those in Mexico, but that was surprising. Are they not there?
I don't know. I'm just saying I've I've never seen
one in real life, so I'm sure that was surprising
to see. I saw a lizard that was walking, and
it wasn't walking on water, but I think it was
(11:50):
one of those kinds that can I just didn't know
the name of it. Had you recently eaten the worm
from the bottom of the bottom of most cow? Very funny.
Another thing we should point out is that walking upright
is an energy saver. I mean, it's they've done studies
and they found that um, you use about the energy
(12:11):
um rather than you know, bounding around on all fours
like a chimp mte right or like a chimp does.
But to save that energy, to conserve it um, our
pelvis has had to change shape. Like you mentioned, that
was just a consequence of walking upright. Um. And the
reason to change shape is when you walk up right,
if you're a chimp, your body swings side to side.
(12:32):
You have to hold your arms up to balance yourself.
That takes a lot of energy. UM. So we developed
like gluteal muscles and other muscles that can cling to
a specific shaped in size pelvis so that we don't
have to spend all the energy. Our muscles are just
kind of keeping us much more balanced. But one of
the consequences of that of walking upright and our pelvis
(12:54):
changing means that the size of the birth canal afforded
by the hole in the all of us the child
passes through during birth. UM got smaller, a lot smaller.
And it's really strange to think that this the the
decreasing in size of the birth canal actually was one
(13:14):
of the factors that led to an increase in intelligence. Yeah,
and you know, we should point out this is just
the first of what will be a lovely cascade of
theories that we're gonna lay lay on your brains today. Uh,
and that, like you said earlier, there there is no one,
single one. It's kind of when you put all of
this stuff together. I think that's sort of the beauty
(13:35):
of of human intelligence, is it took all of these
great things sort of coalescing um. But the whole thing
with the brain is interesting because the size of the
brain is is one of nature's kind of controversies. Like
we know that as far as humans go, just because
you have a bigger brain doesn't mean that you definitely
(13:56):
will be smarter. But there are some correlations cross species
in nature, uh, and in humans there can be, you know,
evidence that bigger brain means you're more intelligent. But it's
not one of those things where it settles science where
they just say, hey, if you've got a bigger brain,
you're gonna be smarter. No, And in fact, like there's
all sorts of evidence in nature that suggests that's not
(14:18):
the case. Because our brain to body size ratio among
humans is one to forty, So our brain makes up
about our body mass, and that's the same ratio that
a mouse has. My mice just I don't care how
you cut it. They're just not as intelligent as humans.
But on the other hand, an elephants brain to body
(14:38):
ratio is one to five hundred and sixty and elephants
are super smart. So, um, you you can't really find
much there that says, you know, there's no direct correlation
where it's like the bigger the brain, the more intelligent
the being. Um. But there does have to be some
minimum amount of brain size because it seems like the
(15:02):
connections of the brain is we'll see, are what really matter.
And the more brain tissue you have up to a
certain point, the more connections that can be made. Right,
So that brings us back to the birth canal situation.
Like you mentioned you're walking upright, that changes in the
shape of the pelvis, you have a much smaller birth
canal all of a sudden. So evolutionarily speaking, you might think, well,
(15:25):
does that mean we're going to have to have babies
with tiny, tiny little heads and therefore tiny tiny little
brains that may not be able to grow very fast
because it's enclosed in a skull that's sort of locked down,
but that didn't happen to us. What happened was we
have Fontanell's and we have this delayed fusing of the
(15:46):
skull kind of you know, closing for good, and so
it allows and it's you know, it's remarkable still to
think about this to me, but it allows that little
baby head to squish down to get through the birth canal,
and it through the vagina and out into the world
and stay that way for a while. And it's during
that for a while period before that skull completely fuses
(16:10):
that a human brain really really grows a lot, and
chimps don't have that ability. No, a chimp, uh, their
skull fuses mostly in the womb, and their brain, as
a consequence, grows mostly to what size it's going to
reach in the womb. So, on the one hand, a
chimp baby, you could say, is much smarter and much
(16:31):
less helpless than a human baby. But given enough time,
the human baby is going to start to exceed the
chimp's abilities very quickly. And it's because our development is delayed.
We do a lot of developing outside of the womb,
and that's afforded by that skull that's not fused. For
a couple of years after birth. And this was not
(16:52):
there is no intelligent design, so there this was not like, um,
like a good solution or work around. This was just
a natural selected, naturally selected trait, the skull not fusing.
That was a solution to the smaller birth canal, not
to not to increase intelligence, but the advent of babies
(17:15):
being born that didn't have few skulls allowed for the
advent of intelligence. Yeah, a solution to the problem of
walking up right, which is really interesting to think about. Yeah,
And it also just goes to show like it's like
nature is not always like elegantly simple. Sometimes it's really
convoluted and organisms including us are held together by like
(17:38):
duct tape and bubblegum, you know. And that's a good
example of it. I think that's a good time for
the break, yea, yea. And we'll come back and drop
some plasticity on your brain right after this, So, Chuck,
(18:13):
this is the point we're about to talk about brain plasticity.
This seems to be, uh, what if anything explains human intelligence,
and certainly the burst of intelligence that happened thirty to
sixty thou years ago. Yeah, And I think the opening
statement to this whole thing is all you gotta do
(18:33):
is look at the fact that we learn almost everything
as humans, like from the moment we're born. There there
is some maybe instinctive knowledge, but like you said, like
human babies are kind of helpless, little dumb dumbs. And
from that point forward, our brains are are learning and
(18:53):
they're growing, and they're capable of learning, and they're capable
of adapting. And this all has to do with plasticity, right, So,
just if you aren't familiar, plasticity is the brain's ability
to um basically rewire and create new connections as new
experiences come along. Uh, And you can even take old
(19:13):
experiences that you experience more than once and the second
and third and fourth time, those neural connections are going
to become more sophisticated and more connected than they were before.
So our brains are plastic. They can be molded and
shaped kind of like in the rhinoplastic um sense of
the word. They're not made of plastic. They can be
(19:33):
molded and they're molded by the connections that they make.
So it's not necessarily that you have a giant brain.
It's that you human being have a brain that is
really highly capable of creating new connections, and it's those
connections that forms the basis of intellect. Yeah, and that
really frees up, Like once you have a brain that's
(19:55):
plastic and that can evolve, you know, to figure out
a pro ablem rather than taking eons and eons to
have like genetic to genetically adapt to a solution to
a problem. If all of a sudden you have a
brain that can figure something out, you do it so
much quicker, and that frees you up to do more
and learn more, and it creates this feedback loop all
(20:18):
of a sudden where the process really really speeds up.
And that's you know, basically what we saw thirty sixty
years ago. Yeah, and the reason and we're still seeing
it today, Chuck. I mean, like you know, a thirty
to sixty thousand years ago, it was a huge burst
of creativity and intelligence, but we're still talking about changes
that took place over thousands of years. Now. We're seeing
(20:39):
changes to the human condition in our society that takes
place over like tens of years. So it still seems
to be speeding up and we're still going through the
same process. But the I guess the best way to
think about what you've just described as evolution, which typically
you know, UM forces changes on us based on environmental conditions,
(21:02):
goes into the brain, and now it's the brain that's
able to change, and like you said, it changes much faster,
and that leaves genetic evolution or genetic natural selection to
focus on UM selecting for traits that create more and
more intelligence. So it creates that positive feedback loop like
you said, and speeds things up. It's pretty brilliant. So
(21:23):
there's been a lot of really interesting research, especially in
that it seemed like the early to mid nineteen nineties
about plasticity UM. There are a couple of researchers name
to Be and Cosmides great names, and they had a
theory basically that human intelligence UH evolved with all these
UM encapsulated cognitive models, so they did not have the
(21:47):
ability to excess each other. Each each of these modules,
and each one was very specialized for a very specialized
problem or task that was trying to do our problem
that was trying to solve, and that's like a language module, UH,
spatial relation module. UH, here's how to make and use
a tool that kind of a module. And that all
(22:10):
these modules are still around, uh and basically the same
form that they were back then, because it's there on
the timeline of you know, humanity, that that hasn't been
a lot of time to undergo any kind of modifications basically,
So I disagree with that. I think I think on
a speaking about classic evolution natural selection, that's true, but
(22:33):
brain based evolution and natural selection like cultural natural selection,
I think that that's false. You hear that to be. So.
The the idea about all this is that these modules
that we developed over time is like we came upon
new problems in our environments and had to figure out
new solutions to them. They started to kind of get
(22:54):
cross referenced here there, Like you could say, um, you know,
the same the same ability to UM to to follow
the sunset, right, Yeah, I wish I would have come
up with something better can also can also be used
to UM to follow herds of game, right. And so
(23:16):
all of a sudden we now not only just know
to to follow the sunset if we want to follow
the sunset, we also know we can use that same
ability to follow game around. And all of a sudden,
our diet expands that kind of thing. So as these
different modules started cross referencing themselves and and got more
and more connected. We were able to apply these different
(23:36):
things to more and more situations and got more and
more intelligent. All right, So that's UM. That's one sort
of grand theory which I love. Another one that we're
going to talk about is I think super interesting because
some of this stuff is so kind of rudimentary in
it when you just sort of look at it from
(23:57):
a macro view, but when you really have to think
about how important that ended up being, it's it's fascinating
to me. And in this case, we're talking about the
fact that UM. One of the sort of side and
again it's going back to bipedalism. One of the side
effects bipedalism is that we lost our ability, UM, with
our feet to be able to like hang onto things
(24:20):
like chimpanzees do. They were these boots were all of
a sudden made for walking, and they weren't made for grabbing.
And if they weren't made for grabbing, then you couldn't
hang on to mama like a chimp could with hands
and feet. So mama had to hang on to human baby.
And mama can't hang on to human baby all the
time because mama still has to get things done around
(24:43):
the you know, savannah. So what you have to do
then is leave that baby somewhere and go do stuff
like go down to the river and uh and do
things and uh. If you leave a baby somewhere, what
you go down to the river and do and things?
Two things you know unen uh and if you leave
(25:05):
that baby And this is all leading to this statement,
if you leave that baby somewhere, you want to be
able to go back and find that baby. And it
seems so rudimentary and basic, but that is a huge
thing in the development of the early human brain, is
simply to spatially map and remember, like where I have
left this child. It's important to go back and get
(25:25):
that child, and I can do that. Yeah, and then um.
Consequently to that, another adaptation seems to have arisen from
the same problem, the problem of not being able to
cling to the mother anymore, and then also the problem
of the baby being otherwise helpless, way more helpless than
a baby chimp. Right, So they think that around the
(25:47):
same time baby's cries developed, like you don't hear other
things necessarily crying like a human baby, And they don't
think that babies cried like that until around this time,
because there was that problem. So even if a mom
couldn't remember where she put her baby, she could listen
out for the baby crying. And they also think around
this time that an urge or desire to soothe the
(26:09):
baby from its crying would have developed, and that it's possible, Chuck,
And this makes so much awesome sense that language actually
developed out of what's called mother ease, that kind of
soothing baby talk that calms the baby, that mothers know
how to do just naturally. They think that it's possible
that that is what formed the basis of language. Yeah,
(26:31):
and I'm gonna go beyond that even because what I
noticed when I had a baby in the house was that,
even beyond the soothing thing, if you are holding your
baby and you have to put your baby down to
go wash the dishes or whatever, generally, and I think
I speak for most parents, you don't just go set
your baby down, go in the other room and do stuff.
(26:52):
You're you're talking to that baby from the very beginning,
and you're saying, all right, let's go over to our
little place here. I'll be right back. I'm gonna be
right here in the other whom that baby doesn't know
what you're talking about, obviously, but there's there just seems
to be this evolutionary instinct to to say things to
it right out of the gate. It's really interesting. It
is interesting, and then wrapped up in this also there's
(27:14):
a better example than following the stupid sunset that I
came up with. I love sunsets. But if you can
now all of a sudden like remember where landmarks are
and then wayfind your your way back to you know,
the starting point. Now you can start to use that
to follow game further and further afield, and you're expanding
your range and you can expand your diet. So that's
(27:35):
a really good example of one thing kind of leading
to another, and all of it being um arising from
environmental pressers brought on by changes to buy of us. Yeah,
I love it me too. Um. This next one is
kind of fits in a little bit with a plasticity
I think. Uh. The idea of the cognitive niche um,
(27:59):
which is, you know, typically figuring out like a solution
to a problem. But this theory is that maybe intelligence
evolved as a universal adaptation to all kinds of uh,
evolutionary pressures that we're bearing down. So um and ed
has a pretty great example. If you've got a an
(28:19):
island with a tree that has a certain um fruit
seed that's really beneficial for your body, Um, but you
can't crack into it. There's you know, it would take
a bird, uh, you know, hundreds to thousands or millions
of years to develop and evolved to have a beak
that can crack that thing open. But if all of
(28:39):
a sudden, you know how to make a tool, you
can just walk over and steal that thing from that
dumb bird and just crack it open with the tool.
So it's not filling, it's your brain at work, and
in that case is filling a specific niche. But that's
a tool that was also used to kill the animal
or chop the wood. Yeah, and that really supports what
we were talking about a few minutes ago that once evolution,
(29:02):
once a brain is evolved to a certain amount of intellect,
the brain can take care of the organism and natural
selection and genetics can kind of take a step back
and not have to say, like, um, you know, uh,
select for a thicker harrier chest. Because we're living in
a colder time now because the brain can come up
(29:23):
with a way to create a coat, right, So it
just kind of takes over evolution from evolution by doing that,
and that's that cognitive niche. And one of the consequences
of it is that there seems to be as as
things change in our environment, we figure out new ways
to to solve those, and then those those solutions are
(29:47):
inevitably going to create other problems or changes, So then
we have to we have to evolve even further intelligence
to figure out how to solve these new problems. You
can actually see it still going on today, Chuck, Like,
we've evolved a level of intelligence where we can extract
petroleum from the earth, we can build machines that run
(30:08):
on that petroleum, and we can develop science that figures
out that burning those the that petroleum is really really
bad for the climate. So now we've we've altered our
ecosystem enough that we have to evolve intelligence enough to
figure out how to get out of this new conundrum
that we've created for ourselves based on our previous intellect.
(30:30):
So intellect builds on intellect through environmental pressures that we
often bring on ourselves. That seems like the case, Yeah,
I mean, I think a lot of people seem to
think of intelligence is only solving problems, but it also
creates a lot as well. It's interesting, Yeah, it really is. Um.
I know we were gonna skip this section entirely, but
(30:51):
I think just for frenzies, we should very quickly mention one,
uh the ideas from someone called Terence McKenna who describes
as a post modern Timothy Leary type, one of these
people that that advocates for psychedelic drug use, and just
very quickly the idea is that, uh, the cavemen were
(31:13):
tripping on mushrooms and that's how intelligence evolved. And I
just like mention it because I feel like there's almost nothing,
no leap in history that some person hasn't said, like
the Enlightenment or whatever, like, oh man, they were just tripping, right,
they were just super I don't think it's pretty funny.
(31:34):
It is funny, but it does. I mean, like if
you apply it exclusively to the Upper Paleolithic Revolution, where
all of a sudden there's like art and jewelry and
dancing that stuff, it's possible that it was based at
least in part you know, yeah, you never know, alright,
So I say, we take a break and we come
back and get down to the nitty gritty of how
(31:55):
food might have brought intelligence along. How about that? Mm hmm.
(32:19):
By the way, Chuck, I have a theory real quick
that the more you say uh or um, the more
intelligent you um are. Oh boy, I must be a
smarty pan. You know, other more intelligent podcasts cut all
that stuff out. Yeah, I guess do they? Yeah? I mean,
(32:40):
what did I mispronounced in the Row episode? I couldn't
even substantive Oh yeah, yeah, it's true. Other podcasts would
not have left that in. But that's because dummy leaves
that they're not as brave. We're courageous podcasters. Okay, I'll
buy that. Um. This next theory I think is super
cool because anytime each tie in um, not just food,
(33:04):
but sort of a an appreciation for a creature comfort,
it really like turns turns me on and not you know,
in certain ways intellectually turns me on. And in this case,
we're talking about the fact that we used fire obviously
and then started cooking food, and people that cooked food said, wow,
(33:30):
this is really good, and this taste a whole lot
better than that raw meat. We've been eating this charred
meat is delicious, and let's let's try and do more
of this around here. Yeah, And so that would have
just them being um, responding to like a taste preference,
and that's it. But it just so happened that that
(33:52):
taste preference would have had a really big benefit and
a big contribution to the development of intelligence. Because if
you cook me eat um, you unlock a bunch of
nutrients and calories that are otherwise unavailable to you if
you just eat it raw. So over time, the people
who ate meat would have had more energy and more
(34:12):
calories to contribute to a growing brain, which could have
helped the process along if not sped it up. And
if you consider the fact that we've definitely seen that
that taste and smell has responded to evolutionary pressures in
that we at some point learned not to eat poop,
and we learned not to eat rotten food and stuff. Um,
(34:33):
And that's you know, taste and smell it can have
the you know, it looks like it can have the
opposite effect to where all of a sudden you have
a preference for the good. And that just happens to
work out in your favor. Yeah, and this is another
example of one thing leading to another, where like you know,
mothers developed an awareness of landmarks and wayfinding, and then
that led to um being able to follow game, which
(34:55):
expanded our diet, which led to us eating meat, which
eventually led to applying controlled fire to that meat, which
led to more calories and nutrients available, which led to
bigger brain growth, which helped found uh, the growth of
intelligence and humans. Just one thing, one totally random, unconnected thing,
or even connected but seemingly unconnected, uh, just creating us today.
(35:20):
It's just so nuts. So to me, I love it. Yeah,
me too. And the fact that, like, think about this,
not only the preference for a charred meat, but the
preference for a specific charred meat because you know, different
stuff tastes different. It's not like everything tastes like chicken.
I know that's a joke, but all of a sudden
took took his out there and and says, boy, that
(35:42):
one thing that we killed yesterday. You guys, I don't
know about you, but that was really really delicious. And
we know that that is we saw that thing three
days ago, about fifty miles away. Everyone said, what's a
mile and he well, that doesn't matter right now, but
the point that it was really far away. So all
of a sudden, other things are introduced, like cooperation, not
(36:04):
just wayfinding, but hey, let's let's all get together because
this is like a three day journey and this thing
is really big. That tastes so delicious, So it's gonna
take a few of us to bring this thing down
and to process this animal and get this meat ready
for cooking. So it just introduces like a cascade and this,
and it could have all just come from Hey, that
(36:25):
tastes really great. Yeah, and so that that you know,
these all that hunting and coordinating all that takes like
a lot of intelligence. And not only does it take
intelligence to to coordinate, it takes intelligence to explain what
you're talking about. And it takes intelligence to come up
with that plan in the first place, you know. So
all of those factors combining are just making humans more
(36:48):
and more intelligent with every every step. And again, it's
not like it's just following this perfect linear progression. Yeah,
it's just like it's just kind of randomly. And the
the reason that we're intelligent today is because the attempts
that didn't work out, got selected out, the fact got
trimmed along the way. Is it kind of a ruthless
(37:09):
way to put it, but you know it makes sense. Uh.
And that sort of ties into this other theory of
um smaller prey, like when they were hunting um large
prey species that you know, they eventually uh, they were
hunting and track of these these large animals and eventually
they were driven to extinction. So humans had to start
(37:32):
going after smaller things or I guess, uh, hominem's had
to start going after smaller things, and the fossil record
indicates this. It sort of worked in lockstep with the
evolution of human intelligence. So all of a sudden, if
you're hunting smaller things, you probably have to be a
little bit smarter. You have to be a little bit
more coordinated, you have to cooperate a little more, you
(37:55):
have to maybe invent new tools, and like obviously using
a big thing to smash a large thing isn't the
same thing smashing a small thing. Uh. And just simply
the fact that they had to do a lot more
of it. You know, if you're eating a squirrel uh
as your diet, you're you're eating a lot of squirrel
every day, whereas if you eat a wooly mammoth, that's
your food for the month or whatever exactly. And that's
(38:17):
a really good example of what I was talking about earlier,
that cognitive niche where the more sophisticated we get, the
more problems we actually generate for ourselves, the more challenges,
the more intelligent we have to become. That's right. And
what about this last notion? And then I think this
is kind of where it all comes together, right, Yeah,
so you know, we have like a real urge and
(38:39):
a desire to to wrap everything up in a neat
little package, and we just haven't reached that point yet
with human intelligence. But if you step back and look
at some of the theories, um and see how they
all kind of fit together, it seems like most are.
All of them with the exception of stone date probably
could be right. But they all have to work together
(39:00):
and work with one another, um, which is great because
that level of organization requires intelligence, that's right. But the
key to all of this, and I think, um, we
we talked about the evolution of language on a whole show,
right yeah, uh, we we still don't quite know exactly
how that evolve, but we have some ideas, like we
talked about with the uh, what'd you call it? Mother
(39:23):
ins No, mother ease, mother ease. But all of this
became possible because of language. All of this, like you
were saying, all of this coordination, all this cooperation, anything
that would eventually lead to writing down human history, all
of that had to have language. So it seems that
all of these sort of theories coalescing around the beginnings
(39:45):
of language, and eventually the written word is like the
key to it all. Yeah, totally. And one of the
other things. Um, because we are so aware that we're
intellectually superior, not only to all the other animals, at
the very least, we're intellect really different from the other
smart ones. Um, we tend to think of ourselves as
the most intellectually evolved or the most successful humans ever,
(40:09):
and that's absolutely not the case. Um. I think Homo
erectus was around for one and a half million years
and modern humans have only been around for about three
hundred thousand years. So we're definitely not necessarily the pinnacle
of evolution just in the amount of time and success
we've had so far. But also, um, we have a
tendency to think like we're we're the top and there's
(40:31):
nothing coming. And that's not necessarily true either. Like if
you look at that acceleration and technology, like um, some
of our ancestors used the same tool for a million
and a half years without innovating upon it. They just
made that same tool over and over and over again.
And then somebody came along who was born and figured
out a way to make it better, and that kicked
(40:51):
off more and more technology, and you can see it's
picking up faster and faster. But the fact that evolution
has jumped from the external old for us to our
brains and in turn to our culture, you can make
a really good case that we're not necessarily going to
physically evolve any longer. We're going to mentally evolve. So
(41:11):
it's not it's not certain what humanity is going to
look like in the future, but it's probably going to happen.
The changes are going to happen a lot faster soon
than they have been before, and we'll all just end
up brains and jars right probably or uploaded. That's right.
Oh boy, good luck with that. Everybody that had a
(41:35):
very so long sucker bring to you, got anything else?
I got nothing else. I love these, uh that types
of episodes. Stuff me too. Since Chuck and I agreed
we'd love this episode, it's time for listener mail. So
this is another Appalachian trail probably the last one I'll
read because, Um, Sophie here a k A tough cookie,
(41:59):
which a Sophie's trail name. It's just a lovely human
and we we had a nice back and forth Sophie
and Sophie's sister did a nobo through hike inven and
just had some kind of fun things to point out. Um.
One of the general rules of trail names is someone
else has to give it to you. So I think
(42:20):
that's kind of like, uh, if you're a pilot in
the military, you're like a Maverick and Goose. I think
people think they name themselves cool names. But my brother
in law was like, no, no no, no, no, no, you'd
get a name, and it's usually not something super cool
like Maverick. Yeah, if you name yourself, I'm sure that
people are going to be way harder on you in
the name they actually select for you. Yeah. I don't
(42:41):
even know if you're allowed to. I'm not sure. Uh.
Sophie says that my sister and I cheated a little
bit because we gave names to each other a few
days in. I don't think that's cheating. You're still naming
someone else. Sure, that's called getting ahead of the curve. Uh.
We We did have some unofficial trail names though, that
other people would refer to the pair of us as.
My favorite was a sixty year old Kentucky hiker from
(43:02):
Maine who told us, uh, he referred to us as
the Kentucky Wonders, which is pretty fun. And one thing
I realized after reading all these A t emails is
that it's it's really kind of fun. Like people get
together and like they start off alone and all of
a sudden there's a group of like twelve people hiking
together for weeks at a time. That is the very
reason why I will never hike they that sounds like
(43:25):
a nightmare to me. You would be the uh, the
loner hiker totally. Maybe, like, don't turn your back on
that one. I think your trail name might be Jed Bundy. Um.
The trail through West Virginia is actually less than four
miles and I heard this from other people to um,
not eighteen. So I think we screwed that up. It's
(43:47):
an amazing feeling to go through so quickly after psychologically,
after completing Virginia, which is five hundred miles and a
quarter of the whole entire trail. Uh. And there is
a four state challenge that some hikers will attempt to
do a forty five mile day to go through the
end of Virginia, West Virginia, Maryland, and into Pennsylvania in
two hours. Her family hosts a trail magic spot because
(44:14):
they live near the trail in Tennessee, So they will
go out on the weekends and they pack up a
bunch of hiker food and they grill burgers and stuff
or make pancakes and just feed people on the trail
and then we'll go back home. I think you could
be down with that part, right. Sure, I'd need a
free hamburger, Like can I take it to go? I'd
be like why, I'd be like why is there mustard
(44:36):
on here? But not catch up? Uh. And then finally,
during the hike, we would treat ourselves to podcast for
a couple of hours when hiking was getting monotonous and
wanted to get out of our heads some and your
voices were a frequent, frequent companion listening to stuff that
you should know. Selects these days often have the weird
sensation of remembering exactly where I was hiking in the
woods when I listened to that episode. Uh, come to
(45:01):
Kentucky sometime, check out the Bourbon distilleries and the Red
River Gorge and do a show here Lexington. I know
you'd probably rather go to Louisville or Cincinnati, but Lexington
is definitely worth a visit. And Sophie sent along a
bunch of cool pictures of Sophie and her sister before
and after, and it's just looked like a really great time.
That's awesome. Thanks a lot for that email, Sophie, that
(45:22):
was a great one. And agreed Chuck that one had
to be right for sure. Just stay away from Josh
if you see him in the woods. No, I'm harmless.
I just don't want to be spoken to. That's all.
I want to be left alone. It's too awkward. Otherwise,
you could just hike with a big giant like nineteen
seventies headphones as if you're listening to right with my
(45:43):
head down, sunglasses on in a bag over my head.
I love it. If you want to be like Sophie
and get in touch with us. You can send us
an email and send it off heart Radio. For more
podcasts my heart Radio, visit the heart radio app. Apple
podcasts are ever you listen to your favorite shows. H
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Hosts And Creators
Chuck Bryant
Josh Clark
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Crime Junkie
Does hearing about a true crime case always leave you scouring the internet for the truth behind the story? Dive into your next mystery with Crime Junkie. Every Monday, join your host Ashley Flowers as she unravels all the details of infamous and underreported true crime cases with her best friend Brit Prawat. From cold cases to missing persons and heroes in our community who seek justice, Crime Junkie is your destination for theories and stories you won’t hear anywhere else. Whether you're a seasoned true crime enthusiast or new to the genre, you'll find yourself on the edge of your seat awaiting a new episode every Monday. If you can never get enough true crime... Congratulations, you’ve found your people. Follow to join a community of Crime Junkies! Crime Junkie is presented by audiochuck Media Company.