MALE SPEAKER:
Welcome, everybody,
to one more Talks
at Google session,
today with Joseph Henrich.
The book we're
talking about today
is "The Secrets of Our
Success-- How Culture
Is Driving Human Evolution,
Domesticating Our Species,
and Making Us Smarter."
Joseph Henrich is professor
of human evolutionary biology
at Harvard University.
He also holds the
Canada Research Chair
in Culture, Cognition,
and Co-evolution
at the University of
British Columbia, where
he's a professor in the
departments of psychology
and economics.
He's the co-author of
"Why Humans Cooperate"
and the co-editor
of "Experimenting
with Social Norms."
Please join me in welcoming
Joseph Henrich to Google.
JOSEPH HENRICH: Thanks.
Thanks, Boris.
It's good to be
with you all today.
All right.
So I want to begin by
introducing you to a puzzle,
and the puzzle
has to do with how
it was that our species became
so ecologically successful.
So long before the agriculture
or the first cities
or, especially, industrial
technology, humans
expanded out of Africa
about 100,000 years ago,
parallel to the coast here.
Ended up in Australia by 60,000,
50,000 years ago, into Europe
by 40,000 years ago,
eventually into the New World,
and then down to the
tip of Tierra del Fuego
by about 16,000 years ago.
This is all before the
origins of agriculture,
which begins to emerge
around 12,000 years ago.
While spreading across the
globe, this species of primate
entered a vast
diversity of habitats.
So, arid deserts in Australia.
The malarial swamps
in Melanesia.
Actually got to island
Vanuatu by 40,000 years ago.
Arctic tundra in
Siberia and Canada.
And then, of course, down all
the way to Tierra del Fuego.
Now what's interesting
about our species
compared to other ecologically
successful species
is that we have few
environment-specific genetic
adaptations.
As a species, we're relatively
genetically homogeneous,
especially given the
number of diversity
of environments we live in.
But now if you compare this
to other species-- so say
we took the most successful
invertebrate species.
This would be ants.
So ants have covered the earth.
They control a massive
amount of biomass.
But they've done so by
speciating into over 14,000
different species, and
they have agriculture,
and they have classes.
But they've done it
in a different way--
through genetic adaptation.
So the question is,
how do we do it?
Now I take the
common explanation
to be kind of obvious, and
this kind of a dumb question.
We're intelligent,
so I want to begin
by trying to convince you that
the secret of human success
is not our intelligence--
that we have a process that
makes us smart, that gives
rise to our intelligence.
So I want to start with
dipping into the files
that I call lost
European explorer files.
And these are cases
in which explorers
got trapped in environments
where hunter-gatherers
routinely live in,
and we get to see
if they can survive with their
big brains and ample hubris.
So the case I want to point out
is the Burke and Wills case.
So if you're from
Australia, you've
definitely heard
of Burke and Wills,
the first Europeans to go across
the interior of Australia.
So they started
here in Melbourne,
and they go up to the
Gulf of Carpentaria.
Now this was an expedition
launched for both exploration--
we want to find out what's in
the interior of the continent--
but also the possibility
of running a telegraph
cable from there to there.
It was extremely well-funded.
So they even imported
camels from India
because they thought they
would be good in the desert.
Now crucially, a bit of
information about Australia-- I
mentioned it was colonized
60,000 years ago, so it
was full of hunter-gatherers.
So no agriculture had
ever emerged in there
until the Europeans arrived.
So there's two
different expeditions.
One group of four men takes
off from Cooper's Creek
to make the run.
Another resupply group is going
to meet them in Cooper's Creek.
These guys take 12 weeks of
food, and they head up there.
Now they don't
actually see the Gulf,
but they kind of
smelled the salt air,
found some briny water,
and declared victory
because that was eight
weeks into the trip.
So if you're doing
the subtraction,
they've only got four
weeks of food left.
Things start going
poorly, and then they
start-- they run out of food.
They have to eat
their pack animals.
They're having trouble finding
food, going very slowly.
These guys are waiting
for them, and the deadline
comes when they have to
leave, and they're not
supposed to stay any longer.
They decide to
wait another month,
and still these
guys don't arrive,
so they leave early one morning.
Later that same
morning, Burke and Wills
come in with one other guy.
They lost one guy
along the way who died,
so they have three guys now.
They decide they just
missed these guys.
And they're not going to
be able to catch them,
so the leader Burke
decides their best chance
is to head for a police station,
a police station and ranch
at a place prophetically
called Mount Hopeless.
So these guys start
following Cooper's Creek,
and that's going pretty well.
Oh, so I should
mention that they
were able to resupply
at Cooper's Creek,
so they have a little resupply.
They're going along
Cooper's Creek,
and they end up getting trapped
because their last camel dies
in the mud, and there's
a stretch of desert
that they need to cross in order
to get to the ranch and police
post.
So they can't make the run.
So they're sort of marooned
along Cooper's Creek
for their lack of ability
to find water in the desert.
Now they're struggling
to catch fish or hunt,
but they find they're
able to possibly survive,
and things are looking hopeful
because they get gifts of fish
from the local aboriginals,
the Yandruwandha tribe.
And when they're in
a Yandruwandha camp,
they noticed them
making nardoo cakes.
So the nardoo cakes
are this sporocarp.
So you gather up
these sporocarps,
and the women were
grinding them.
So Burke and Wills
headed out, and they
managed to find some
of these, and they
ground them and they ate them.
So it seemed like
they were going
to do well because they
were getting enough calories
and they're getting
these gifts of fish.
But when they were in the
camp, what they didn't notice
is that the women actually used
a sophisticated processing.
So they grind them, leech them,
heat them, and then only eat
with a mussel shell.
You can't let an
organic substrate-- yes.
AUDIENCE: What year,
roughly, or decade is this?
JOSEPH HENRICH: Oh.
1860 1860.
Should have said that.
Or they grind them, leech
them, and bake them in ash--
because if you don't do
that, nardoo turns out
to be toxic and indigestible.
In particular, it has an
enzyme called thiaminase, which
depletes the B1 in your system.
You eventually get a horrible
disease called beriberi.
So William Wills, a good
Victorian of his time,
was actually writing
in his journal
as he experienced
these symptoms.
And so you can actually
read it online.
It's quite amazing.
So Burke and Wills
eventually die.
They basically poison
themselves and starve to death
at the same time.
The third member of their
group, King, wanders,
delirious, off into the bush but
is rescued by the Yandruwandha
and eventually gets rescued by
a team that came from Melbourne.
OK.
So what this and
many other tales
like it tell us is that
despite months actually
in the outback with supplies
in order to prepare,
these guys couldn't
figure out how
to survive as hunter-gatherers.
They couldn't figure
out how to survive
in the environments
in which we evolved,
in which humans have
lived in for 60,000 years.
So no specialized
mental models fired up.
No instincts models
gave them the ability
to figure out what
they needed to know.
And no general intelligence
helped them figure it out.
And they couldn't find water
or identify edible plants.
Now you might think, well, that
would be pretty hard to do.
No animal could do it-- except
some of their camels escaped,
and now the interior
of Australia
is full of feral
camels, because camels
have-- they can smell
water from a mile away,
and they have innate
taste and sense
cues which allow them to eat
the right plants for them.
And so even in a completely
novel environment,
they can find the right
plants, but humans can't.
One important thing that Burke
and Wills didn't know about
was something that
Australians commonly use.
This is a plant called spinifex,
and if you break these off
and you smash them, you get
these little crystals off
of it.
Then you can heat
them, and it makes
a resin that is as strong
as cement once it hardens
but soft and pliable
when it's heated.
So that's really useful
for making tools.
OK.
So they couldn't hunt or
actively make spears or make
fishing hooks, but
this is something
any local adolescent could do.
So you can ask the
question, what was missing?
What they were missing
is what the adolescent
gets, which is this
download of a vast body
of cumulative
cultural information
that has built up
non-genetically
in this whole system of cultural
inheritance over generations.
So they didn't get that,
so they can;t survive.
So this is something that
really makes humans different,
and it's going to be the
main thing I'm going to be
emphasizing as I go along here.
But I want to come to
this intelligence question
from a different angle.
So this is an experiment done
by Esther Hermann and Mike
Tomasello at the Institute
for Evolutionary Anthropology
in Leipzig.
And what these guys did
was they put this series
of different primate
species-- so you've
got your three
primate competitors--
into a series of
18 cognitive test
to see how well they
did on the tests.
It's actually a
picture of my son Josh.
He's a representative
2 and 1/2 year old.
So it's the three primates, and
the humans are represented only
by 2 and 1/2 year olds.
We'll come back to that.
So if you break the 18 tests
down into different categories,
there's tests about
how you can understand
space, how you understand
quantities, causality,
including tool use
here, and your ability
to do social learning,
to observe someone
doing a demonstration
and then take advantage
of that demonstration.
And you can see
how well they did.
So the humans here--
you know, the humans
are doing about as well
as the chimpanzees here.
No different in quantities.
The orangs are doing a little
bit worse in each place,
in causality about the same.
And then the big difference
is really social learning.
And this finding is
actually deceptive
because they had trouble
finding a test where
the two-year-olds
weren't at ceiling
and the apes weren't at floor.
So they finally
found a test where
the apes could do it sometimes
and the humans didn't get 100%.
So this doesn't give
you the usual picture
of humans being much smarter.
So, for example, in
the tool use test,
the chimps actually
out-compete the humans.
So the chimps are
better at tool use
compared to 2 and 1/2 year olds.
Now--
AUDIENCE: Sir, what was
the age of the primates?
JOSEPH HENRICH: The primates
actually vary in age.
So there were infants-- so
chimpanzee infants go up
to age 5, and then
juveniles and then adults.
So this included infants
and adult chimps.
Same thing with the orangs.
Now what's interesting
about that-- and this
is a point I was going to come
to in a second-- with humans,
this guy's going to get much
smarter as he gets older,
and he's going to get much
better until by the time
he's an adult, he
could smash these guys
and get 100% on all the tests.
These guys don't get
better as they get older.
In fact, the five-year-olds
and the four-year-olds
are just as good as
the 25-year-olds,
so they don't get better
in the cognitive abilities,
and that's going to
be part of our story.
Question?
AUDIENCE: What is
the rationality
behind studying human kids?
JOSEPH HENRICH: Right.
So, great question.
So why not put them
up against the adults?
And part of the reason
is Mike Tomasello
and his collaborators
want to see what
an uneducated
human that has less
of the cultural download that
he's going to eventually get.
So the idea is to minimize
the cultural input,
and you'll see why that's
important in a second.
Because we know the adults
could beat the apes here.
So the question is, how
do the kids look like,
and what's the age trajectory?
So I think I'm going to
eventually get to your question
more directly.
In the book, you'll see that
there's other experiments.
So for example, you
can take the chimps
and compare them
to undergraduates--
and it doesn't matter what
country they're from--
and compare them
on working memory.
And the chimps are faster
at working memory tests,
so they have faster processing
speeds, and at least some
of the chimps can tie or even
beat the humans in the working
memory tasks.
And tests of
strategic thinking--
so there's a game in economics
called the matching pennies
game, and it
requires you to play
what's called a mixed strategy.
So you play a certain strategy
some percentage of the time
depending on the payoffs.
And chimps are great at that.
They zoom right in on what
the economists predict
is the Nash equilibrium.
The humans systematically
miss it and can't hit it.
They seem to have some strange
biases that prevent them
from getting there.
So at least on these
counts, it doesn't
look like humans are
obviously endowed
with some innate
brainpower that gives them
a big advantage on the apes
except in this domain, where
they really crush the apes.
OK.
So this is the point
about the age effect.
Why do humans get smarter?
AUDIENCE: Could you
just clarify what
you mean by social learning?
JOSEPH HENRICH: Sure.
So I'll tell you
what the task was.
So the task was you had some
hard-to-figure-out problem
or you had to get some
food out of a tube.
All these tasks are
incentivized by food.
All three species like snacks.
So you got to see a demonstrator
use a tool to push the food out
or get the food out
in some other way,
and then you see if the
other, the observer,
will use that technique or
is able to get the food out.
OK.
So to head off-- because there's
kind of an obvious problem
here.
We know that humans
are much smarter, so
how do you explain that?
So part of the
answer for sure is
that we culturally inherit
pre-built solutions
to lots of problems.
So it's the software,
not the hardware.
So just to give you a
sense, if you grow up
in a world with screws,
springs, levers, and pulleys,
those things are
easy to figure out
and then reapply if
they already exist.
But they're actually--
each one is hard to invent
and emerges at different
points in human history.
My favorite example
is the wheel concept.
So if you look at Gary
Larson cartoons or something,
it'll look like cavemen
are doing wheels,
but the wheel is actually
invented relatively late
in human history.
So, 6,000 years ago.
It's only invented in
Eurasia, so it's never
invented Australia
or the Pacific
or anywhere in the New World--
except some Mayan toys seem
to have wheels,
but they didn't put
it to use, letting their dogs,
for example, pull these carts.
Elastically stored energy.
So you can make spring
traps and bows and arrows
by storing energy in
bendy things and things
with elasticity.
That's not invented in the
continent of Australia,
and neither is compressed air.
But once you have
these things, you
can then reapply them
in different ways.
Let me give you another example.
So you all, by virtue
of learning English,
are endowed with a
system that allows
you to count without bounds.
So you can differentiate
27 from 28.
It's packaged into these
nice packets of 10.
But lots of societies
that anthropologists
have studied count
1, 2, 3, many.
And then in New
Guinea, you can find
a whole range of societies.
Some count to 27, to 34,
to 12, and then they stop.
So if you have this
counting system
and you have to
distinguish 37 from 38,
it's hard because you don't have
any way to mark those, at least
linguistically.
There are sort of techniques
to get around the problem,
but they're not
nearly as efficient
as having a good
numbering system, which
we know evolved over
cultural evolutionary time.
And I'll give you
one final example.
So English, like lots
of modern languages,
is endowed with three separate
spatial coordinate systems
for referring to and, it turns
out, thinking about space.
So one is north,
south, east, and west.
So that's the absolute
coordinate system,
and you could say
hey, I'll meet you
on the north side of the house.
And if we both know
the coordinate system,
we can both meet on the
north side of the house.
There's an ego-centered
coordinate system
with its front,
back, left, right.
And you can attach that
to a house and say,
I'll meet you in
front of the house.
And people have a sense of
what the front of the house is.
There's also a relative
coordinate system.
So this is where you could draw
yourself a line between myself
and the books, and I
could say I'll meet you
on the left side of the books.
And then we would have
a sense of where to go,
and that comes from this
line between the books and I.
But lots of languages only
have one or two of these,
so they don't have
right and left
or front and back, so they
have no ego-centered and no way
to say the relative
right to left.
So if you had to set the
table, you'd have to say,
put the fork at the
north end of the table.
And then you'd have to have a
different rule for every room.
So this is a spatial
coordinate system
which helps us, gives us new
tools for thinking and doing
things.
Driving on the left would
be impossible in populations
that only have absolute
coordinate systems-- north,
south, east, and west.
All right.
So that's just some
of the examples
that we get for free by this
cultural inheritance that
helps us solve more
and more problems.
So the key, the
secret of our success,
is not our intelligence but our
cultural abilities, the fact
that because we're such
powerful social learners,
we can accumulate ideas,
beliefs, values, heuristics,
bodies of know-how,
bits of our language.
And these accumulate over
time, and they form what
we call cultural adaptations.
I'll give you lots
of examples of these,
but these are packages
of these ideas, beliefs,
and values that
help people solve
different kinds of problems,
and it's cultural inherited.
The key to these--
and so this is a very
mathematical
enterprise, so there
are lots of models of
cultural evolution.
You can assume different
amounts of fidelity
of cultural transmission,
and you can assume
different amounts of sociality.
And you can show that
you get different rates
of cultural accumulation, and
you get different equilibria.
So the amount of
cultural accumulation,
how sophisticated
your technology gets,
actually depends on
these two things.
OK.
And once you have this, it
gives rise to collective brains.
So how good a society is at
developing new technologies,
new ways of solving problems,
new institutions, how
fancy their language
is, the number
of words in your language
depends on the size
of your collective brain.
So, the interconnectedness
between people
and the flow of information.
Now the next step is
that this is important,
but then it turns out to
have been important for much
of our species evolution.
So this actually drove
our genetic evolution,
and we have the interaction
between two kinds
of inheritance systems, genetic
and cultural inheritance.
So one of the problems
why I think-- well, it's
kind a little bit of sociology--
but why this idea has taken
a while to take
hold and influence
human evolutionary
biology-- yes.
AUDIENCE: The
previous slide-- that
sociality was very important.
If that's true, then why do
we have so many introverts?
Why didn't we then select
for more extroverted people
that are going to have more
social interaction with others?
JOSEPH HENRICH: Well,
compared to lots of species,
we're actually quite extroverted
and quite willing to engage
with people from other groups.
So I'll give you example.
When two different
chimpanzee groups meet,
if the two groups
are equal size,
they're going to start
hooting and hollering
and gradually back
away from each other.
If one group is much
bigger than another group,
they're going to try
to kill the other guys.
So you have very
hostile relations
between chimpanzee groups.
But humans live in these--
at least traditionally,
humans live in
tribal groups which
have all kinds of
relationships between groups,
and when you meet someone
from another group,
you begin to figure out
what your connections are,
what your social
connections are.
So, I mean, maybe we're
not as outgoing, as
friendly as we could be, but
we're certainly a long way
from other primate species.
One of the reasons why I
think we've had trouble
getting this idea, why this
idea didn't get traction
before recently,
is because there
is this sense in which there
are cultural explanations
for behavior, the
kinds that you might
get from social psychology
or from anthropology,
and then genetic or evolutionary
explanations, the kinds you
might get from biology
or sociobiology.
But what this approach
does is it says,
let's take the logic
of natural selection
that has helped us explain
so much of the natural world
and apply it to understanding
culture and cultural evolution.
So, how should natural
selection have shaped our minds
to make us better learners?
And so you think
about the capacities
for cultural learning,
and then these--
once you have
something that you can
make an assumption or an
empirically grounded assumption
about psychologically,
you can then
build models of
cultural evolution.
So if everybody is using a
set of learning strategies,
they interact.
Where does that process go?
And then finally, the gene
culture co-evolutionary point
is that this is going to feed
back and get this loop here,
which I'll say more
about a minute.
OK.
Now I want to give
you a little bit
of a sense of how we can use
the logic of natural selection
to think about learning.
And so you can say, how might
natural selection shaped
our brains, and what kinds
of content should we look at?
So should we be
interested in knowledge
about plants and animals,
about sex, about fire?
Things like that.
Or you can say, who should
we pay attention to?
We have this whole
world full of people we
could attend to and learn from.
Who is most likely to have
information useful to me
later in my life or now?
And then finally, how do I
integrate that information?
So he's doing one thing.
She's doing another thing.
He's doing a third thing.
How can I balance
that information?
So this is the approach
we take, and these
are mathematical models of
genes and culture co-evolution.
So just some sense-- there's
now quite a bit of evidence
that children and
adults pay attention
to cues of success or skill.
So if someone's more
successful or better,
if someone's better
at playing golf
if you care about
golf or shooting
arrows if you're
a hunter-gatherer,
then you preferentially attend
to them and learn from them.
Cues of success actually
integrate more things.
So in hunter-gatherer
groups, you
can look at the guy who
brings back the most big prey.
Doesn't say exactly
how he did it,
but you know he's
doing something right
if he's able to consistently
bring back the most big prey.
Cues of prestige are kind
of a second-order effect.
So if everybody is
doing this, and they're
trying to figure out-- who
should I pay attention to
in my social group?
Then you can step
back and look at who
others are paying attention to.
So who's being deferred
to in conversation?
Who are people tending to watch?
Who do people say
nice things about?
And those are cues of
prestige or deference.
And that helps a
learner, in combination
with these other cues, zoom in
on people most likely to have
good information for them.
Age seems to be
an important cue.
So for young children,
this can be valuable
because a young child has
to scaffold up their skills.
So they might-- if you're
a five-year-old in a hunter
gatherer community, you might
know who the best hunter is.
He's probably about 38
or 40, but his skills
are way too advanced for you
as a five-year-old to get to.
So you can look at the
best seven-year-old,
and then when
you're seven you can
look at the best nine-year-old.
So you can self-scaffold
your skills up that way.
Another interesting way in which
you can pry information out
of this system is to
look at older people.
So in lots of societies, not
everybody gets to be old,
so by the time you have people
who are 60, 70 years old
in a small-scale society,
natural selection has taken
out a bunch of other people.
So if you get to be
60 or 70, there's
informational content in the
fact you've got to be that old.
And then finally,
self-similarity cues.
So if the sexual division
of labor is at all old,
and lots of paleoanthropologists
think it is,
then males should tend to
focus in and learn from males,
and females should tend
to focus in and learn
from other females.
Same thing with
dialect and ethnicity.
So in order to get
the right norms
for the people you're
most likely to interact
with later in life, it seems
our psychology, at a young age,
causes us to key in on those who
speak a language like our own
and preferentially both interact
with them and imitate them.
So these cues-- there's
now ample evidence
that this is relevant for
lots of different domains.
There's differing
degrees of evidence
for all these
domains-- but really
basic things like
food preferences.
So if you want to get your child
to like a certain food that he
or she doesn't like, you
should put him at a table
with same-sex kids who
are slightly older.
And they also have to
like the food that you're
trying to get the kid to like.
So there's good
experimental work
on that showing that they'll
shift their preferences.
What people like in mates can
be affected by these things.
Economic strategies.
Suicide actually spreads
through these things,
so when a celebrity
commits suicide,
people will copy method.
And you can predict
that it's going
to be people who match
them on sex and ethnicity,
statistically speaking.
And motivations for
fairness and punishment
also can be
transmitted this way.
OK.
Now what this says--
you can't see.
It's blocked here.
But these things these
appear to be adaptations.
So they reliably develop.
We see them in children
as young as one.
They operate automatically.
People don't know
they're doing it,
and they can often
remain unconscious.
So there are adaptations,
mental adaptations
for cultural learning.
Now once you have those--
and individuals interact.
So, say, generation
after generation, you're
copying those who are most
successful and healthy
and have all those cues.
You're going to eventually
be able to produce
cultural adaptations without
anybody knowing about it.
Let me give you an example.
So two biologists
studied the patterns
of spicing around the earth.
And other animals
don't use spices,
so this is kind
of a funny thing.
You don't get any
nutrition from spices,
and there's no caloric
content to spices
and nothing significant.
And the other thing
is, when you begin
to look at the active
ingredients in spices,
they've often evolved
to keep mammals away.
So natural selection has favored
capsicum in chili peppers
in order to prevent
mammals from eating them
because they want
to be eaten by birds
because birds do
better dispersal.
So the chemicals
in this actually
taps right into some
of our pain systems
and causes us to feel pain.
The thing with humans is we
can see someone experience
pain-- I mean, see someone
eat a chili pepper--
and they're going to experience
what would be pain for most
animals, but if they
seem to like it,
we can learn to like it.
So we seem to be able to
overcome our innate aversion.
So chimps won't
eat chili peppers,
and babies don't
like chili peppers.
This is why they recommend
to nursing mothers
not to eat too many
chili peppers, because it
gets into the milk, and the
baby might not like the milk.
But these spices seem to be--
they are used in the hottest
climates, and they
seem to be chemically
active against pathogens.
So if you use the
spices typically
found in traditional
recipes-- they're
typically meat
recipes-- they actually
reduce the load of
pathogens in the meat.
They're effective
against pathogens.
So they're kind of a
pathogen reduction system.
And correlations
across the globe-- you
don't find people in
Norway using many spices.
The Inuit don't use many spices.
But when you go
into the tropics,
there's lots and lots of spices.
They tend to be the
spices most effective
at suppressing
pathogens, traditionally.
Another one is corn.
So when the Europeans
arrived in the Americas,
there were many populations
dependent on corn, maize.
And the thing about maize is
if you become dependent on it,
it actually-- you can't get
enough niacin from maize
unless you do something very
odd and non-intuitive to it,
which is to mix in an alkali.
So you can put burnt
seashells into it.
You can shovel ash out of
your fire into the corn mix.
And then what that
does is it chemically
breaks open the niacin,
and then you can get to it,
and you don't get a terrible
disease called pellagra.
Now we have a natural
experiment that shows us
that this is hard to figure out.
So all these different
Native American groups
had figured out various
versions of this trick,
but when the Europeans took
it, it comes over to Europe,
and it becomes a staple food
in many poor populations.
And there were
epidemics of pellagra
that went on for centuries
until-- actually,
the guy who figured out was
Joseph Goldwater, an American.
But it took him
years to convince
the medical establishment.
They all thought
it was a pathogen.
And then finally, I've
done this work in Fiji,
and there are these
food taboos against
particular marine species when
women are pregnant or nursing.
And when you begin to
look at the species,
you find that they're all
ones high in Ciguatera toxin.
So if you've spent any time
in the tropics living off
reef fish, this is some
you've got to watch out.
Don't eat the moray eel.
And there's a number of
other species-- barracuda--
who are potentially
high in Ciguatera toxin.
So this is a case where
there's a bunch of taboos,
which-- people don't
know why they have them.
They just know-- pregnant?
Breastfeeding?
Don't eat these fish.
The taboos kick in.
And the taboo seem
to be effective.
Women during those
periods don't have
any kind of fish poisoning.
So these are adaptations
that evolve unconsciously
over generations that
people didn't figure out
or have any causal model for.
And the book is full
of lots of these.
OK.
Now once you begin to--
once you accept that
and you begin to study it, you
come to the collective brain
idea, which is that larger
and more interconnected
populations will generate
more rapid cultural evolution,
and the equilibrium of how
fancy their tools, technologies,
and practices can get is higher.
It also means that if suddenly
a population is cut off,
they will begin
to lose know-how.
So you've got to maintain
that size in order
to keep your
adaptive complexity.
So let me show you a
little bit of evidence.
So this is research done by
Michelle Klein and Rob Boyd.
And it's hard to study
continental populations
because technologies and
ideas can move fluidly,
and it's not clear
what a population is.
How do you kind of isolate that?
But in the Pacific, it's easier
because you have islands.
Now of course, these islands
aren't all disconnected.
There was movement between them
and people moving between them.
But it at least gives you a way
to encapsulate a population,
and then you can measure the
amount of interconnectedness.
So they measured how
fancy the tools were
in these different
islands in the Pacific,
and they went back
to-- you know,
this the ethnography
from the first arrivals,
from the missionaries
and the anthropologists
and the early
explorers, on how fancy
the fish-getting or the marine
foraging technology was.
And they used a simple method.
Nobody's ever really completely
satisfied with this method,
but you take each tool,
and you break it down
into a bunch of component parts.
So each tool gets a measure
called techno units.
It's the number of
parts in the took.
OK.
So these are the population
sizes of the different islands,
and the islands are
represented there,
and that's the number of tools.
So you can see the
larger the population,
the more tools they have.
And the larger the
population, the higher
the number of average
techno units per-- so
there's more tools and
more complicated tools.
Now the high and low contact
is whether the islands were
sort of isolated for
long periods of time
or whether they
had routine trade
contact with other islands.
And contact has an independent
effect on populations.
So you can look at
this graph, and you
can see that the high
contact islands tend
to be above the regression
line I've shown here,
and the low contact
tend to be below.
It's 10 data points, so
it's not that big a sample.
All right.
OK.
So that is consistent
although there's
lots of things that could be
affecting those technologies.
These guys did a whole
bunch of regressions.
They included all kinds
of ecological variables.
In general, it seems to hold up.
But of course, you only
have 10 data points,
so you have to put the other
variables in one at a time.
But my grad student, Michael
[INAUDIBLE] Christian and I--
we wanted to see if we
could replicate this
idea in the laboratory.
So this is with
100 undergraduates
at the University
of British Columbia.
And students come into the
lab, and what they have to do
is they're given a complex
image editing program,
and they're told they have
to replicate this image.
And the closer they get to
this image, the more money
we will pay them.
So they're paid in cash.
They have a time limit.
And for everybody
but the first--
so there's going to be
a bunch of generations.
So there's going to be a
bunch of guys that come in.
They do this once.
And then another group comes
in, and they get information
from the previous generation,
and then they get to do it.
And they can pass information
down to the next generation.
We do this for 10 generations.
And either you can only
access one other person--
one person came before you,
and you learn from them.
Pass to that guy, that guy.
Or you can look at all five.
So you're this guy,
but you can check out
what all these guys did.
And then 10 generations.
So that's the "one
or five" models.
So after you do it, then you can
write up information and pass
it down to your students, so
you get two pages of things
to pass down.
So your student gets
your product-- so,
whatever image you made.
They also get this,
so they get to know
what you're trying to get to.
And they get your write up.
So then we can take
each image-- and we've
done this a number
of different ways--
but you can get a
measure of similarity
between whatever the person
made and this target image.
So you get a score.
So, 10 generations.
You can see in the
"one" model treament--
that's the blue-- those guys
never really go anywhere.
They just kind of bounce around.
They had a really good
first round, actually,
but then things bounce around.
And these guys start
off slow there,
but then they just
take off, right?
And so they end up with
much higher, much more--
they're producing
images much closer
to the target image
over 10 generations.
People are randomly assigned
to treatment groups,
so we know there's no
intelligence difference,
but something about the
informational dynamics
let these guys do a lot better.
It's also clear
from other analyses
that each learner is recombining
ideas from the other learners.
So this allows people to
come up with innovations
without invention, because
they are recombining ideas
from other learners.
This is kind of a
fun thing to look
at because you get to see a
big chunk of the data here.
So this is the "one" model
treatment and the "five" model
treatment.
This is each generation.
So you can see the "one"-- this
first generation of the "one"
models did pretty well.
Those things look
moderately like that.
These guys did terrible.
I don't know.
Some people didn't
even turn in answers.
But then things awry here
on the next generation,
and these guys aren't really
going anywhere here at all.
But then things click in.
You get this guy, and
then you get these guys,
and then things are rolling, and
these guys are chugging along.
By the time you get to the end
here, the worst one in round 10
is better than
the best guy here.
And that's just all
informational dynamics.
OK.
Let me give you the
case of the polar Inuit.
So I mentioned earlier
one of the things
about the collective
brain is the possibility
that you can lose information.
So we have kind of a
natural experiment.
So these are the northernmost
group of hunter-gatherers
in the world, the polar Inuit.
And two explorers, Elisha
Kane and Isaac Hayes,
winters with them in
the 1850s and-- 1863.
And they lacked many of the
technologies, the fancy tools,
that Inuit typically
have that have
been recorded by so many other
explorers an anthropologists.
So Inuit houses typically
have a long entrance.
It's a heat system.
You keep the heat
outside by trapping it--
to the snow houses.
They don't have that.
They lack the bow
and arrow, which is
necessary for hunting caribou.
Inuit typically have
complex compound bows.
And the fishing leister, which
is these three-prong fishing
spears.
So when you spear a fish,
you need the prongs.
Otherwise, the fish will
just slide right off.
So they lacked all
three of those things.
And crucially,
they lacked kayaks.
So they lost the
ability to make kayaks.
Things were going
wrong, so they were
limited on what they
could hunt and fish,
and their populations
were declining.
Now crucially, John
Ross, another explorer,
had been there in the
1820s, and he records them
as having all these things.
So sometime between
1820 and 1850, 1860,
they lost all of
these technologies.
Now later, a Norwegian named
Knud Rasmussen figured out
the puzzle here.
It turned out that after
Ross had been there,
there had been some
whalers visiting,
and this initiated
a plague which
took out the most senior
members of the community.
So with them died
their knowledge.
So this means the information--
the community took a quick hit
from the plague, but
then it was never
able to be regenerated by
the people in the community.
He meets this guy--
Rasmussen meets this guy--
and he tells him the
story about how they came
to have the technology again.
Because by the time
Knud's there in 1900,
they have all the
technology back.
So after the plague, they
weren't able to regenerate,
and then this guy
is traveling north.
He's a Baffin Island Inuit.
And they encountered him, and
he had his group teach them
all the stuff they'd lost.
So they were able
to get it back.
In some sense, you
can think of them
as being reconnected to
the collective brain.
And that they-- in part
because they lost kayaks.
So they couldn't go to
other groups and get it.
They sort of became marooned
in that part of Greenland.
And there's good
circumstantial evidence
to believe this account is true.
So they were hunting again
with their bows and arrows,
and they were using
kayaks for the seals.
The population
decline had reversed,
and it was increasing.
And their kayaks that they used
resembled the Baffin Island
type and not the one typical
of western Greenland.
So you can see that
it was actually
him that taught it because
he came from Baffin Island.
Now eventually, in
the next 50 years,
their kayaks revert back
to Western Greenland,
but that's because
they've been reconnected.
So now they're more connected
to the rest of the Greenlanders.
The next thing, the next
point I want to make,
is-- so there's all
this important--
these cultural adaptations
and on this accumulation
of know-how, but
this has actually
affected our genetic evolution.
So in the book, I spent
time trying to figure out
when the process of cumulative
cultural evolution got started,
and I think there's good reason
to believe it started over
a million years ago.
So the way to think about this
is once our genetic evolution
gives us enough
cultural capacities
to get cumulative cultural
evolution, you create
an autocatalytic process.
So cultural evolution
produces a few tools
that are better than individuals
could make on their own.
You get fire and cooking and
some tracking information
and food.
And then you're a learner,
and you can either
try to figure this
stuff out for yourself,
or if you're good
enough learners,
you can learn it from the other
members of your community.
And so that's going
to favor brains
that are better at
doing cultural learning,
at acquiring and organizing
all of this information.
Then once you have
bigger brains,
you're going to increase
the size of this pool.
So you get this
interactive effect
where no matter how
big your brain gets,
you're going to have more
valuable cultural information
that, if you can't
learn it and acquire it,
you're going to lose.
Now this process of
course eventually hits
the stops because of
the primate body plan.
The canal where the
baby has to come through
can only get so big,
and so natural selection
has shaped us so that our
babies are born premature.
Their heads kind
of squish up when
they come through the canal.
Other primates don't
have this problem.
And in fact, our babies
are born about a trimester
too early because the woman's
body has to get the baby out
before its head gets too big.
So this has kind
of hit the stops,
but of course this problem
continues to spiral.
And we soon we have a division
of labor between males
and females and then other
kinds of division of labor,
external storage systems,
etc. as that information
continues to expand.
OK.
Now at the same time, it's
creating a general pressure
for brains that are capable
of organizing and storing
this information.
It's also creating specific
genetic adaptations.
So these are genetic
adaptations that we
have that are driven
by cultural evolution.
So let me start off
with some physiological
and anatomical examples.
Fire and cooking.
So my colleague Richard
Wrangham at Harvard
has analyzed our
digestive tract.
So our teeth are small.
We have stomachs that are
too small for a primate
of our size.
Our colons are too short
for a primate of our size.
We don't seem like we
have these anomalies
relative to other
primates, but they all
make sense if you think of us
as an obligate cooking species.
So we're required to predigest
our food in some sense
by cooking it or
processing in other ways,
making it easy to chew so
we don't need small teeth.
Breaks it down.
Now the interesting thing
about cooking is fire.
As my book shows in lots
of lost European explorers,
we're terrible at making fire
when we need to make fire.
You know, unless we have
technology to make fire,
we're not good at just
figuring out how to do it.
So we need this
cultural know-how
to figure out how to
make fire and to cook,
but then that
shaped our biology.
The same is true of--
let me go to running.
So Dan Lieberman has argued
that our bodies are adapted
for long-distance running.
So we have this
amazing sweating system
that other species
don't have, that dumps
sweat onto us that can only
cool if you're actually running.
We have springy
arches in our feet
which other primates
don't have, and we
have a new, cool ligament
in the back of our head
here which allows our head and
shoulders to turn independent
of each other whereas chimps
are kind of like this, right?
They can't do that.
And other animals
that have that are
things like horses and
other running species.
So those are two
physiological examples.
And oh, I'm sorry.
In this case, the reason why
you need the culture stuff
is the sweating system--
there's a reason, tracking.
But I'll tell you
the sweating one.
If you look at-- so it
looks like an amazing system
of adaptations for
long-distance running.
We can outrun all
kinds of animals.
We can outrun dogs.
You know, these other animals
can't do marathons or even come
close.
But we have this
great sweating system,
but there's no water tank.
So you start running.
You would immediately run out
of stuff to put in the tank.
You wouldn't sweat, and
the whole thing collapses.
And the way hunter
gatherers do this--
when you study hunter
gatherers who are chasing down
antelopes-- is they have
knowledge about where
to find water, and they
have cultural technologies
for carrying water,
like ostrich eggs.
And so you need that
cultural know-how in order
to make this system work.
So it's a package of genetic
and cultural adaptations.
Now developmental
psychologists have
noticed that young
children seem to have
a specialized system for
acquiring information
about plants and animals.
So a simple example is
category-based induction,
which is never learned.
We do it automatically.
So if you learn that
Felix the cat likes milk,
you don't just assume,
well, that's Felix.
Felix has a particular
taste for milk.
You generalize that
to all cats, and you
assume it's a feature of cats.
And then if I say, well,
what about a tiger?
Would a tiger like milk?
You can say, well,
probably, because, you know,
they're kind of related,
and I think they're close.
So if I had to bet,
tigers would like milk.
So we have this system
that we don't learn that we
seem to get automatically.
Same thing about artifacts.
Kids readily distinguish between
different kinds of artifacts,
and when they know
something's a tool,
then they begin to
say, what is it for?
When it's not in
the tool category,
they're less concerned
about function.
So they apply a functional
stance to tools.
Humans seem to have
two kinds of status.
One kind of status we inherited
from our non-human primate
ancestors, chimpanzees.
So chimps have dominant status.
Dominant individuals can
control costs and benefits.
They do it by force
and force threat.
But humans have another kind of
status that's due to this fact
that when you have
a social group,
they're going to vary in
their knowledge and skill
and abilities.
And if someone has a lot
of knowledge, skills,
and abilities and you're
a social learner--
you can learn from other
people-- then you can tap that.
And now you want to pay
them deference in order
to get access to
their information.
And here the ethology
is totally different.
So in dominance, you stay
away from the dominant.
You don't look at him.
Keep your head down.
But if you gotta
learn from him, you've
got to watch him
and get close to him
so you can learn from him.
So you lead to two
different kinds of status.
And there's a lot of
research on psychology
about how human status
partitions into these two
kinds.
Cultural evolution also
produces social norms,
so we acquire rules
about how to behave
and, we acquire rules
for judging others.
And once you have
that, then you can
have these mutually
reinforcing stable equilibria,
where-- economists, they call
these Nash equilibria, right?
Once everyone's
there, we have a rule.
Everyone has to wear clothes,
and if anybody deviates, is not
wearing clothes-- but
then different groups
can get very different
norms, and this
can get sorted
out through groups
competing with each other.
But we seem to have
a norm psychology,
so we're prepared from
a young age to say,
I don't know what the
rules are in this world,
but I know there's
rules, and I've
got to start trying to figure
out how to learn from them.
And we have lots of inferential
machinery to help us with that.
And then finally, we seem to
have an ethnic psychology.
So cultural evolution
goes first here,
and it produces a world in
which different groups have
different norms, and they're
marked by different markers
like dialect or
dress or whatnot.
And then young learners
readily key in on that.
And I mentioned before how
young kids preferentially
learn from those who
share their dialect.
That's because they need to
get the underlying information
because they're going
to be interacting, most
likely, with members-- at least
in traditional societies--
of those who share
their dialect-- are also
going to share their norms.
That's who they're going
to have to interact with.
I'm happy to say more about any
of those, if you're interested.
AUDIENCE: Yeah,
I have a question
about the last comment.
JOSEPH HENRICH: Yeah.
AUDIENCE: So my understanding
is that at least is something
that you see in other animals,
especially in other mammals,
right?
That they-- you'll have
some area in Africa
with a bunch of
different animals,
but the animals of
a particular species
will congregate
together rather than
with other animals that
are kind of related
but not the same species.
So it's a different, maybe,
level of categorization,
but it's still kind of selecting
other people or other animals
to stay with that
are very like you.
JOSEPH HENRICH: Yeah.
So the big difference
is whether it's
your local group of familiars
that you grow up with
or whether this can be applied
to someone you've never met.
And so that's, again, this idea
that humans live in tribes.
So there's strangers, but if you
share these cultural markers,
then you're preferentially
interacting,
preferentially learning.
Animals don't do the
social learning, either.
Yes.
AUDIENCE: I'm sold.
Culture sounds great.
So why don't all
animals do this?
Why are we so different?
JOSEPH HENRICH: Yeah.
So that's a great question,
and that is, like-- let's see.
Chapter 17.
No, 16.
So there's a startup problem.
And the problem is
when culture is rare,
it's not-- natural
selection doesn't
want to make the
investment in making
you a good cultural
learner because if there's
nothing out there to learn,
then it's a wasted investment.
So in that case, you should
invest in individual learning
and make you better at figuring
out things on your own.
So the only way to jump
start the whole system
is to somehow get a lot
of cultural information
out there in the
minds of others.
Then selection can favor
a brain that can take
advantage of that information.
So it's kind of like a fitness
valley when you do the math.
So in the book, I lay out a
case for how we could have
crossed that fitness valley.
And I don't posit any magical
genes that suddenly appear.
I posit an ecological
circumstance.
So in the Pleistocene,
humans faced intense pressure
from predators.
And what animals do when they
face a predator from pressures
is they live in bigger groups.
And I talked earlier-- if
you have a larger group,
you're more likely to begin
to get this process going
because there's more
people to learn from,
more individuals to
have individual ideas.
And it was probably
a savanna dweller
because they would have been
most susceptible to predation.
There's a number
of other factors.
The climate was
starting to oscillate
in a way that
would have also put
a pressure on social learning.
So in the book, I kind of put
together-- and that's the idea,
is that those ecological factors
push you across this thing.
You begin to turn the wheels on
cumulative cultural evolution,
and then you can do
the selection pressure
and it'll pay off.
AUDIENCE: So are
there other animals
who may be good at
social learning who
could have done this
and may be not so
good on the other
measures of intelligence?
JOSEPH HENRICH: Yeah.
Well, throughout the book,
I used chimpanzees a lot
because chimps do have
some cultural traditions.
And this is relevant
to this point.
So chimps live in these
fission-fusion groups,
and they do transmit things like
techniques for nut-cracking,
techniques for getting at ants.
A few other things.
And the problem is that most
of the time, a young chimp
is only with mom, so
you can only ever have
vertical transmission.
But if you had a group that
was pushed into large groups
by predation, then
the young chimp
could look at all these
different potential models
and learn not just from
mom but from ants and all
these other possibilities.
So chimps are a
cultural species.
Another interesting
species that's relevant
are elephants and dolphins.
Elephants have some
cultural learning.
And actually, one of the
things I talk about in the book
is the evolution of menopause.
And elephants and at least
some species of toothed whales,
of cetaceans, have
menopause, too.
And I think there's similar
cultural stories that
could help explain that.
Basically, if you have
some cultural abilities,
when you get old, there's
an opportunity for you
to shut down your
reproductive system
so you can continue
disseminating
your cultural knowledge
to the younger generation.
AUDIENCE: I always find sports
teams really interesting.
You know, when
they're young, they're
just focusing on the sport.
But how do they become a coach?
For example, Jacques Lemaire.
He said he couldn't read,
but he's won a Stanley Cup.
And you see-- I don't know
if you've studied those.
And what's the factors
that are playing in--
because those people, they're
not going into MBA programs.
They're not in business.
But how do they go from a
player to running a organization
that's quite complex?
JOSEPH HENRICH:
So, how do people
end up running sports teams?
AUDIENCE: Yes, when they
started off as a player.
Because it's a completely
different skill.
Is it the institutional
knowledge, or are they--
JOSEPH HENRICH: Yeah.
So I haven't studied
that, but my intuitions
would be that they're
heavily influenced
by the coaches and the
managers and all the people
that they were exposed to
over the course of their time.
So they're kind of the
old-fashioned style
apprentice-style learning.
All right.
So this is just a quick review
of the stuff I've talked about.
So we can approach
our learning abilities
as adaptations for
extracting information
from the social world and
also from the environment.
So one of the things we
focus on is-- when should you
use social learning?
When is that optimal?
And when is it optimal
to switch over and rely
on your own experience?
This creates a second
system of inheritance
which leads to a culture-driven
genetic evolution.
So I briefly pointed
to some examples
that I discussed in the
book of how culture has
driven our genetic evolution.
One of the things I didn't
get much chance to talk about
was the process of
self-domestication.
So I mentioned how cultural
evolution gives rise
to social norms
and institutions.
So this means that
if you deviate
from what the group
does, you're going to get
punished or a bad reputation.
People gossip about
you, be mad at you.
But that's eventually
going to get
people to be more compliant,
to fall into line,
and to do with the
group wants them to do,
to be more conformist,
more docile.
So you get this process
of self-domestication.
It's part of the process that
makes us more cooperative.
So one of the things I
discuss a lot in the book
is the evolution of cooperation.
Didn't fit into today's talk.
Now if we can expand
our cultural brains,
we can generate faster
cumulative cultural evolution,
more innovation.
And then a final point
that I'll leave you
with-- there's a whole
chapter on this--
which is that culture is
part of our biology in two
separate ways.
One, that our genetics have been
shaped by cultural evolution.
But the second is-- and
people often separate culture
from biology-- but when you
learn to read, for example.
So that's a cultural practice.
You got to learn to read.
It actually changes your brain.
You have a thicker
corpus callosum--
that's the information
highway that connects the two
brains-- after you've
learned to read,
if you compare literate and
non-literate populations.
You have a larger verbal memory.
You actually have
specialized circuitry
that's specifically
for recognizing letters
in your left hemisphere.
So culture shapes our biology
in non-genetic ways as well.
And that's the end.
AUDIENCE: Everything you said
makes a lot of sense to me,
but there's one
aspect of evolution
that I'm wondering
whether or not we have any
or you have any better
understanding of, because it
seems to me that there's
a necessary requirement
for either kind
of evolution that
requires a certain amount of
variance in the population.
And if that's the case from a
cultural standpoint, that there
would be a risk or that you
wouldn't want the population
to be too good at
learning-- otherwise
you could latch
onto the wrong thing
and then everybody's dead.
Is there any sort of
understanding or any evidence
or model to understand
how that works
or where the right balance is?
JOSEPH HENRICH: Yeah.
I mean, that's the
right intuition.
So that's certainly what
we get from the models--
is variance is the engine of all
these evolutionary processes.
The thing about
culture-- one reason
to worry about that
less is actually-- it's
more of a worry of
genetic evolution,
because genetic replication
is so much more exact
than cultural transmission.
Even when people
are good copies,
there's still lots of noise.
And the other thing that
culture has is multiple models.
So genetic
evolution-- you either
have one parent or
two parents, usually.
Some exceptions to that.
But in cultural evolution,
you could have 50 parents,
and you're actually
recombining ideas.
So your actual
repertoire doesn't
look like any are 50
parents because it's
a recombination of all of those.
So it can definitely happen.
There's probably specific
cases of maladaptation
where everybody was forced
to do exactly the same thing,
but in general,
I think it's less
of a problem for
cultural evolution.
AUDIENCE: So just
a quick question
on the feedback loop between
genetic and cultural evolution.
Seems like that the
genetic problem might not
be very relevant today.
There's not a lot of lions and
bears around outside, right?
So how does the cultural
evolution look today?
What's your thought on that
for the next 100 years?
JOSEPH HENRICH:
Yeah, I guess I don't
think there's
been-- if anything,
there's been an acceleration
of gene-culture co-evolution
in the last 10,000 years.
So one of the things
I do in chapter 6
is I discuss recent evidence
from the human genome
on gene-culture co-evolution.
And so one good well-studied
example is lactose.
So some populations
domesticated cows and then
didn't develop cheese
or yogurt technology.
So this created a selection
pressure for people
to be able to-- normally, in
humans, like in other mammals,
babies can drink milk, and then
the whole system shuts down
for adults.
So adults can't process
milk and get the sugar
and the nutritional benefits.
But in some populations that
had this particular cultural
situation, selection favored
keeping that system on.
And it's a change
on chromosome 2,
and it just wipes out
the regulatory gene
that normally prevents the
lactose gene from operating.
So you get adults who can
drink milk into adulthood.
And this has spread faster
than any other known gene,
essentially.
There's also genes for
alcohol dehydrogenase
that seem to be associated with
the emergence of agriculture.
So I think there's good
reason to think that culture
is actually more of a pressure
on human genetic evolution now.
AUDIENCE: How do you think
this would affect family size?
Do you think somebody could
use this as an argument
against having an only child,
reasoning that they have fewer,
say, older siblings they can
look up to as cultural parents?
Or do you think that's not as
relevant because we normally
raise our kids in
large group settings?
JOSEPH HENRICH: Yeah.
So I think that
probably isn't relevant
because-- so in all our
studies of young kids,
they seem to be very willing
to look widely and learn
from all kinds of
other individuals
besides their siblings.
So I've worked in three
small-scale societies
in the Pacific, in Peru,
and in rural Chile.
And there, the kids
live in a big group,
basically, in the
middle of the village
or on the beach in the village.
And I mean, of course older
siblings have some influence,
but they seem just as happy
with the neighbor's older
sibling or--
AUDIENCE: So in this light, I
see kind of a positive feedback
loop that keeps our
brains getting larger,
keeps our culture
getting more complex
and advanced until we reach
that limit with brain size.
At the same time,
my understanding
is humans used, basically,
stone tools for the better
part of 100,000 years
without a lot of advancement,
which doesn't seem
to jive with this.
Yet somehow in the
last few millennia,
technology got a whole
lot more advanced.
How do all these
things square up?
JOSEPH HENRICH: OK.
I mean, let's see.
This is chapter 15.
I go through the
stone tools, and I
don't think there's
any evidence of stasis
in the anthropological record.
So tools get better.
Adhesives get added.
Projectile weapons are in.
You got spears, wooden
spears, at 400,000.
AUDIENCE: But this is on
the scale of millennia.
I mean, think what we've done
in the last two millennia.
JOSEPH HENRICH: So
things are going slower.
Yep.
So definitely there's been
an exponential explosion,
but that's actually
what you get out
of the models when
you begin to consider
the size of populations, the
emergence of communication
technology where you have more
and more minds interacting.
You have trade routes
that's running information
across different, and then
you have recombination
of different ideas.
Right.
Writing.
All kinds of communication.
Yeah.
So that's what I think happened.
AUDIENCE: Chapter 15, huh?
MALE SPEAKER: Speaking
about the domestication
of the human species, how
would you connect that
with, let's say, contemporary
politics of Democrats
and Republicans and big
government, small government?
Is there anything
going on there that
is-- or is this just a
completely disconnected effect?
And the other, at
the same venue,
is-- I mean, obviously group
learning-- that advances
society and advances
our culture,
but there's also
groups of people
that did less palatable things.
Is there any comments from
your angle about those things?
JOSEPH HENRICH: So one of
things I didn't talk about
is-- using the same
kind of approach,
you can think about the
emergence of maladaptation.
So the stuff I
talked about often
gives rise to
cultural adaptations,
but there are interesting
models in which--
and then I think actual
empirical cases--
where the whole thing
goes completely awry.
And the easiest
one to understand
is the prestige situation.
So if you have something where
there's a certain cue-- and so
I'll give you the
Melanesian example.
So in Melanesia, men got
prestige for growing yams,
and so people copied
the bigger yam growers.
But then they began to
have competitions to see
who could grow the biggest yam.
And then they grew
bigger and bigger yams,
and they would
have a competition.
But it turns out when yams
get to a certain size,
they're not edible anymore.
So there's all these guys
putting all these resources
into making these giant yams
which are largely inedible.
So that's kind of
where things begin
to get maladaptive from the
genetic evolutionary point
of view.
But the guys are, you
know-- they're into it.
In fact, the Fijians
have yam competitions.
A group I worked with.
The contemporary
politics question.
It seems to me-- so
one of the things
that this kind of
suggests is that we have
a tribal psychology, that we're
looking for people to build
relationships with that
share our cultural beliefs,
speak our language
in the same dialect,
share our same cultural cues.
And so I feel like that has
relevance for understanding
some political division.
AUDIENCE: I was
wondering, also--
I mean, a lot of the
culture that we have is--
so if you look at, say, the
culture the chimpanzees have,
it's tool use that is
consistent with their biology.
But a lot of--
especially when we
get to more complicated human
tools, they sort of crucially
rely on things like opposable
thumbs and separately
but movable digits that
other primates don't have.
So do you feel
like, again, there's
some sort of feedback between
the evolution of culture
and the development
of these things?
JOSEPH HENRICH: So I didn't
talk about it in this case,
but there's a bunch of
changes with our nerves.
So our ability to
sort of directly
move each finger and
whatnot is probably
a co-evolutionary effect
of co-evolving with tools.
So tools are evolving
culturally to fit our hands,
but our hands are also adapting
to be better at using tools.
This is very clear
in our tongue.
So we've clearly had evolution
to make us better language
users.
AUDIENCE: So you talked
about the benefits
of learning from a large
number of different people,
different adults.
But these days,
one of the things
that we've heard about a lot is
that the internet is becoming
an echo chamber, so
you tend to learn only
from people that are
very, very similar to you,
and you're able to
effectively filter out
other opinions and views.
Does that bode badly
for our future?
JOSEPH HENRICH: Yes.
Nah.
So this fits into the
interconnectedness problem,
right?
So if the internet is-- so.
Right?
The great promise
of the internet
is it fully interconnects us
and we can learn all this stuff,
but if we're only
connecting to people
we like or are
very similar to us,
then you lose that flow of
ideas and the diversity,
the power that comes from the
variation in selection systems.
AUDIENCE: I loved
your presentation,
and sorry if this seems a little
insulting, but how much of this
is new ideas?
And I ask because a
lot of what you said
reminded me strongly of some
kind of old science fiction
like Larry Niven's
Ringworld, where society
degrades due to disconnection.
JOSEPH HENRICH: OK.
I don't know
Ringworld, but this is
stuff that draws together
things I've been working on
since the mid-90s.
So, 20-something years of stuff.
So yeah, it varies in how
new it is, but in some sense,
it's sort of my career up
to this point summarized.
AUDIENCE: What other questions
about evolutionary biology
are scientists still trying
to look at and answer
right now that maybe we sort of
have some vague theories about
but maybe are bigger questions
that people are still
trying to solve right now?
JOSEPH HENRICH: Well, I
think the big-- I mean,
the center of a lot of
debate is the origins
of human cooperation, and that's
one of the real flash points.
So the position I
defend in the book
is that it's been a
culture-gene interaction
and that inter-group
competition is really important.
But there's another
group of scholars,
for example, that
really reject the idea
that inter-group
competition was important,
that groups were
kind of fighting
with each other and those who
had the best ways of organizing
won and then that led to a
gene-culture co-evolutionary
process.
So cooperation is certainly one.
I mean, with the
human genome, we're
really just-- it's kind of
a Wild West, New Frontier
time because there's so much
interesting genetic variation
that we're finding.
And just going
through and looking
at what caused that
variation, a lot of it's
turning out to be cultural
differences among populations
that then lead to
genetic differences.
MALE SPEAKER: And with
that, let's please
thank our guest today.
