Are We Getting Dummer
[Music]
about six years ago
in august of 2015 i took a business trip
to china
with my friend and business partner kobe
bryant pete delgrosso
and a few other colleagues we had a
number of meetings scheduled but the one
thing about travel in general
and travel to china specifically is
plans always
change a dinner with the ceo one evening
was cancelled last minute
so we found ourselves stuck eating
dinner at our hotel in shanghai
over dinner we caught up on business
family and then shifted to one of our
favorite topics
biology in nature we talked anecdotes
fun stories
oddities of nature concepts like how the
cheetah uses its tail to stabilize
itself as it leaps
how termites invented air conditioning
how ants created a version of the
internet
millions of years before humans did but
eventually
we moved on to my favorite topic the
human brain
given my background studying the brain
it was always fun to surprise people
with random anecdotes
it still amazes me how little people
know about our most important organ
the one that makes us conscious and
think and feel
the truth is though even experts don’t
know very much about the brain
as an example when i was in graduate
school we thought there were about a
hundred billion neurons in the human
brain
these are the fundamental building
blocks the computing units
and all you need to do is count the
little buggers but by my first book
the number had dropped we overcounted i
guess
and by my second book the number grew to
about 85 billion neurons
we missed a few so the most fundamental
thing about our brains
something we just have to count we don’t
really know
the thing that struck everyone most that
night though was when i casually
mentioned that regardless of the number
of neurons
our brains are actually shrinking mind
you
size doesn’t really matter we don’t have
the biggest brain in the animal kingdom
that honor goes to the sperm whale and
most brain scientists don’t think
absolute size matters at all
rather it’s the size of our brains
relative to our bodies
something known as encephalization but
even there
we don’t have the largest
encephalization the tree shrew of all
animals wins that award
but what does matter is how big our
brains are compared to our ancestors
and for most of hominin history our
brains were growing
both an absolute size and an
encephalization
and almost everyone agrees that the
growth and brain size over the past few
million years
has been responsible for our growing
intellect as our brains got bigger
so too did our mind’s abilities and
that’s where things stood
up until about 50 000 years ago when
things
seemed to have gotten a bit weird
somewhere around that time
our brains started to shrink and not
just by a small amount
i told the table that night to think of
our brain as roughly the size of an
american football
over the last 50 000 years we lost the
size of a baseball
in brain mass a baseball
my colleagues were in disbelief what
actually they almost seemed mad at me
for even suggesting it
but eventually someone asked the obvious
question
are we getting dumber i said we don’t
know
it’s possible that we’re losing
intelligence
but it’s also possible that something
else is happening you see brain size
tends to follow body size
which is why encephalization is so
important and it’s true
that our body size is also getting
smaller but that can only be part of the
story
both because our brains were previously
outgrowing body size
and on a relative basis our brains more
recently we’re getting smaller
as a percentage of body size our
encephalization levels are actually
shrinking too
there were plenty of theories to go
around and i shared a few of them
the most fun one was that some scholars
believe we’re getting domesticated
there’s actually strong evidence that
brings a domesticated animals
horses cows dogs cats shrink as a result
of domestication
they essentially lose their mammalian
brains
the area that focuses on being in the
wild but that was unlikely for us
because humans seemed to have lost brain
mass more broadly
and the decline has continued well past
our supposed domestication
so kobe did what i’ve seen him do so
many times before
he put his hand on his chin stroked his
beard
stared me down paid me a compliment and
challenged me to figure it out
so there i was in china with a challenge
i figured with the jet lag i wasn’t
going to sleep anyways so i said i would
see what i could come up with
that night i scoured the internet read
every journal article i could come up
with
and ultimately turned up empty-handed i
spent the next evening
doing much of the same and then went
back with my tail between my legs and
told kobe i couldn’t find anything but i
agreed to keep looking
weeks later same story
i researched every avenue i could find
many scholars
thought we were losing intelligence
others thought it was body size
some thought domestication as i’d said a
few thought it was structural but most
thought it was an anomaly just not
knowable
but at least i had my answer there was
no answer
so i told kobe who didn’t take it
particularly well
he said to me do you remember what i
told you
it was a fair question we were
jet-lagged and drinking really bad
whiskey that night
but i remembered and i told him so he
looked at me to be
to be fair he looked down at me because
we were standing
and said i didn’t say find out who has
the answer
i said find the answer if no one’s
figured this out
you should now i had some pretty
daunting phd advisors at brown and mit
but kobe was altogether different he
really didn’t take
no for an answer and i don’t know was
even worse
so i hemmed and hawed reminded him we
had a business to run
but reluctantly agreed to see what i
could come up with
for years my research became a running
joke
almost every time i saw him and it
didn’t matter who we were with
he would ask what have you got for me
jeff
everyone around us even my team figured
he was talking about business
we’re asking me to deliver bigger
returns or something truth is
neither of us cared to ask how the
business was doing our business was
doing amazing
there was no need to ask no kobe was
asking if i found an answer to the brain
science question
and each time i would say i’ve got
nothing
it wasn’t for lack of trying i ran down
every avenue
i started doing research in archaeology
paleontology physical anthropology
i reached out to neuroscientists
geneticists geochronologists
anthropologists i would have talked to
harrison ford if indiana jones was real
i started doing independent research
measuring fossils literally filling
skulls with all kinds of substances
to determine the size of the cranium and
then convert that into brain mass
estimates
i still have today what i believe is the
largest collection of brain size data
on the planet but i didn’t have
answers and then with the help of a
physiologist at johns hopkins medical
school
i found an answer the physiologist a guy
by the name of chris ruff
is a leading scholar of bone and body
mass changes in hominins
he wrote a seminal paper in nature
including data about how our body size
changes over time he even had some data
on brain size changes
chris was kind enough to give me updated
data on bone fragments and then formulas
to convert them to body mass
and when i compared the body mass
changes to brain size
sure enough body and brain size
correlated
even as the brain started to decline
as you can imagine i was pretty excited
i shot kobe a note hey we need to talk
we met at the nobu in newport beach
which had just opened
and with a half moon smile i fed him the
answer
no we’re not getting dumber it’s just
that our body sizes are shrinking
and the brain generally follows body
size just like all organs
that simple but kobe’s hand went back on
his chin
sat for a few minutes thinking as if
there was something to think about
i spent nights and weekends put off a
book we were writing together
i lost sleep but i found the answer
but when kobe finally opened his mouth
all he said was why
why why of course why how could i be so
stupid so what our brains are getting
smaller because our bodies are getting
smaller
why are our bodies and brains getting
smaller kobe my phd advisor
was right i didn’t answer the question
at all i just solved an interim step
so i responded the only way i knew how
more sake
and i drank and then i ubered myself
home that night
so for the next few years i continued to
do research
and continue to work on the problem but
i didn’t get very far
i had ideas but they were all just bad
ideas
and then early last year i lost my
friend
and everything changed it was
devastating
and it reminded me of the things that
mattered most in my life
so i decided to reprioritize
family and friends first the business
must
go on and i was determined to find an
answer
to why our brains are shrinking so i put
my hand on my chin
and i told myself you have one year
one year to find an answer no exceptions
over the course of the past year i asked
myself
every morning the same question kobe had
asked of me
what have you got for me in most
mornings i came up blank
but i persisted i continued to write
journal articles to make sure that my
thinking remained sound
and one day a criticism came back that
gave me an idea
a reviewer asked if i had controlled for
geography because different locations
had very different weather
and weather happens to affect body size
it turns out that people who live in
cold climates such as antarctica
or alaska tend to be stockier than those
who live in warmer regions
and this is true of the past as well
hominins evolved
to adapt to differences in geography
because of regional climate
the reason for this is thermodynamics
because our bodies produce
so much heat we need to regulate for
different environments
well the brain is the biggest energy
suck when it comes to all of our organs
our brains weigh roughly two percent of
our total body mass
but consume over 20 percent of our
energy
so it’s likely that our brains would
also need to adapt to thermodynamic
changes
if it were true for geographic
differences
i wondered if it could also be true for
climate change over time
i reached out to a few
paleoclimatologists and they provided me
with
millions of years of detailed sample
data you have to love scientists
business people would never share data
sure enough there was a strong
correlation between climate change
and both body and brain size during
cooling periods
our bodies and brains were significantly
bigger and during global warming events
our bodies and brain shrank there was
over a 10
percent difference in size across the
past 50 000 years
same pattern and of course during the
most recent period of global warming
we should then expect both body and
brain size to decline
and they did there was a slight twist
data is
never clean in science the last 1 000
years or so
has shown significant decreases in brain
size but body size has actually grown
so our encephalization shrunk but there
too we found an answer
it turns out we’re just getting fat
when you control for bmi or body mass
index the differences go away
so the answer is our brains are getting
smaller because of global warming
and they’re getting smaller relative to
the body because our bodies are putting
on
excess fat yet another reason to rid the
planet of climate change
and obesity there’s much more
to this story than science and finding
the answer to our shrinking brains
it’s also about how the best people push
us to go deeper
be better just as in the game kobe
pushed me further
made me dig deep on something in which i
thought there was no answer
even though it was in my own field he
never took no
or i don’t know for an answer our best
mentors do this for us
they push us inspire us
we give far too little credit to those
of us who teach
mentor coach we credit the individual
with success
whether it’s the scientists the ceo the
star athlete
the politician it’s worth asking if the
people behind the scenes
are in fact more valuable the people who
nudge
push motivate drive others that really
move this world forward
we should pay more credit to the
teachers in our lives and for my part
let this serve as a reminder of the good
that my friend did in this world
both for others and for me thank you