You know, there's this this persistent idea that
really groundbreaking science is always done
in a pristine whitewalled laboratory. Right.
Yeah. You picture the stainless steel, the bubbling
beakers, maybe a supercomputer humming in the
corner, hazmat suits, the whole thing. Exactly.
But history has a funny way of contradicting
that image, because sometimes the biggest shifts
in how we see our own species happen in the most.
The most mundane place is imaginable. Like a
greyhound bus rattling through rural Illinois
in the early 1970s. Yes, a bus ride. That is
exactly where we're starting today. For this
deep dive, we're looking at a stack of sources
centered around one specific landmark paper from
1972. Titled The Apportionment of Human Diversity
by the evolutionary biologist Richard Lewontin.
And the reason we're doing a deep dive into this
today isn't just because it's a classic piece
of biology though. I mean, it absolutely is.
It's because this paper essentially took a sledgehammer
to one of the most ingrained concepts in human
history, which is the biological concept of race.
And it did it using math. I think that's the
key here. Yeah. Before this paper dropped, the
conversation about race was largely visual or
social or philosophical. It was what you could
see. Right. But Lewontin turned it into a raw
numbers game. He asked a question that seems
simple, but is actually incredibly complex. Yeah.
When we look at the biological data, do these
racial categories we use every day actually exist?
But it wasn't the final word, was it? Because
as we went through the sources for this, and
we have articles from the Royal Society, critiques
from Cambridge geneticists, even some pretty
heated social media threads from just recently.
Oh, yeah. It's still a huge debate. Right. It
became really clear that this 50 -year -old calculation
is still sparking massive fights online. It's
basically the definition of a zombie debate.
It just won't die. You have the original finding,
which was a total bombshell. Then you have the
mathematical counterargument, often called Lewontin's
fallacy, which we will definitely get into. We
have to. And now you have political groups weaponizing
that counter argument on the Internet. It's a
mess, but it's a fascinating mess because it
sits right at the intersection of hard math and
human identity. So the mission for you, the listener,
and for us today is to parse that mess. We need
to understand what Lewontin actually calculated
on that bus ride, why a mathematician named Edwards
said he missed the point, and where the scientific
consensus actually lands today. We should probably
set the scene first, though. Back up to the 1960s.
Let's do it. What was the scientific vibe regarding
race at the time? It was a bit of a battleground.
You have to remember, for centuries, race was
just treated as a given. You look different,
therefore you're biologically different. But
by the 60s, you had two major schools of thought
clashing in anthropology. Right. Our source material
calls this the Kleins versus Buckets debate.
Which I love as a visual. It's a perfect way
to visualize it. Yeah. On one side, you had the
buckets camp. These were scientists like Siedosius
Dubzanski. Who was a giant in the field. A total
giant. And actually, Lewontin's mentor, which
adds a bit of personal drama to this whole thing.
But Dubzanski and his camp believed that human
races were discrete populations. Meaning you
could draw a hard circle around a group of people,
say, Europeans or Africans, and say, this is
a distinct biological bucket. Precisely. They
believed that if you looked at gene frequencies,
distinct racial groups were valid biological
realities. They thought the buckets were real.
But on the other side, you had the Klein's camp,
led by anthropologist Frank B. Livingston. And
he famously said, There are no races. There are
only clines. Yeah. So for anyone who hasn't taken
an anthropology class recently, let's unpack
cline. It's essentially a gradient, right? Yes.
Think of a hill or an incline. Imagine walking
from Oslo, Norway, all the way down to Lagos,
Nigeria. You're walking from a very high latitude
down to the equator. That's a long walk. A very
long walk. But the point is, you aren't going
to step over a magic line on the ground where
people suddenly stop being one race and start
being another. It's a smooth transition. Every
village looks pretty much like the village five
miles back. Exactly. Skin color, height, hair
texture. They change gradually based on geography
and exposure to the sun. Livingstone argued that
because these changes are continuous, drawing
a line and saying here's where this race ends
is scientifically arbitrary. You're trying to
force a fluid spectrum into a rigid box. Exactly.
So up until the late 60s, this was mostly a semantic
fight. One side looks at skin and says, I see
a gradient. The other side says, I see enough
difference to make a category. It feels like
they were just talking past each other. They
were. And that's largely because they were looking
at phenotypes, the outside stuff you can see.
But then technology shifted. And this is the
real pivot point. We moved from looking at phenotypes
to looking at genotypes, or at least the molecular
products of genes. Like blood group proteins.
Yes, blood proteins and enzymes. So we could
finally ask, OK, we look different, but how different?
are we chemically on the inside? Which brings
us to the setup for our guy, Richard Lewontin.
So Dobzhansky, his mentor and the big bucket
guy, asks his student, Lewontin, to write a chapter
for a book on evolutionary biology. Right. He
basically hands him this brand new molecular
data and expects him to finally prove that race
is real on a firm quantitative basis. Talk about
a backfire. I mean, Dobzhansky probably thought,
finally the math is going to prove me right.
So Lewontin takes the assignment and he decides.
to run the numbers himself. But here's the kicker.
He doesn't have access to a university mainframe
to run these complex statistics. He has a lecture
to give down in Carbondale, Illinois. Right.
So he hops on a bus south of Chicago. A three
or four hour ride. And his toolkit is just laughably
analog by modern standards. I mean, today we
have AI that sequences genomes in seconds. What
was he actually working with on that bus? It
really is a time capsule. He had a stack of reference
books full of blood type data from around the
world. He had a notepad, a little hand calculator.
And my absolute favorite part, he had a table
of logarithms to do the multiplication. A table
of logarithms? I tried to explain log tables
to a younger colleague the other day, and they
looked at me like I was churning my own butter.
It's a lost art. It really is. It's incredibly
tedious work. He sat there looking up numbers
in the books, using the log tables to multiply
them, writing down the results. He spent that
entire bus ride manually calculating something
called the fixation index or FST. Let's break
that term down because fixation index sounds
a bit intimidating. What is he actually measuring
there with his notepad? At its simplest, it's
a way of partitioning diversity. It's a statistical
method to figure out where the variation in a
system is actually coming from. Okay. Imagine
you have a few bags of mixed marbles. The FST
tells you how much of the color variation is
due to the difference between the bags versus
the variation within a single bag. Okay. So Lewontin
is asking, if I look at all the genetic variation
in humans, that tiny 0 .1 % of DNA that makes
us different, where is it located? Is it found
between the races or is it found between individuals?
Exactly. He categorized the data into seven huge
classically defined racial groups. to test the
bucket theory. And he used the standard classifications
of the 1970s. Right, Caucasians, Africans, Mongoloids,
South Asian Aborigines, Arans, Oceanians, and
Australian Aborigines. He used 17 indirect markers
since full DNA sequencing wasn't available yet.
And he wanted to know, is the difference between
these huge groups the main source of human diversity?
And this leads us to the 85 .4 % rule. This is
the number that seemingly ended the debate and
cemented Lewontin's legacy. It was a statistical
bombshell. Lewontin found that if you take all
human genetic variation, a massive 85 .4 % of
it exists within any given local population.
Let's contextualize that for a second because...
85 % is a huge number. If I go to a single town
in, say, Poland or a village in Thailand, 85
% of the total genetic diversity of the entire
human species can be found just between the random
individuals in that one town. Yes, that is exactly
what it means. The genetic gap between you and
your next -door neighbor is, statistically speaking,
the vast majority of the difference that exists
in humans anywhere. The variation within the
group is massive. That is just so counterintuitive.
We feel like our neighbors like us and someone
from across the ocean is different. That's the
visual bias talking. The math says otherwise.
He then looked at the differences between populations
within the same race, like the difference between
Swedes and Italians. And what was that number?
That accounted for about 8 .3%. Okay, so 85 %
is individual, 8 % is local nationality. What
was left for the big races? The buckets. Only
6 .3%. That's it. That's it. All the history
of us versus them, the segregation, the global
identity politics, it's all based on 6 .3 % of
our genetic variation. That is the finding. Lewontin
concluded that because the variation between
races is such a tiny fraction of the total, the
concept of race has, in his words, virtually
no genetic or taxonomic significance. He basically
said the buckets aren't real. Or if they are,
they are so shallow they don't matter. Now, I
can hear the skeptics. And frankly, I'd ask this
too. Was Lewontin just biased? Maybe he was a
progressive guy who wanted to prove race didn't
exist, so he found the numbers to match. That
is a very fair challenge, and it's one that has
been thrown at him for decades. Right. But we
actually have a control group of sorts. In 1960,
Lewontin used these exact same statistical methods
on fruit flies. Drosophila persimilis. And what
happened with the flies? Did they have races?
They did. He found high variance between the
populations. The math showed that fruit fly populations
were distinct races. So the method works. It
is entirely capable of finding race if it exists.
But the human data just didn't support it. Right.
The fact that he didn't find it in humans suggests
the biological reality of humans is just fundamentally
different from fruit flies. We just haven't been
isolated long enough, have we? We move around
too much. Exactly. Humans are a young species
and we are incredibly mobile. We haven't had
the millions of years of separation needed to
develop into true subspecies. We are a messy
mixing pot. So 1972, the paper drops. It effectively
ends the old measure the skull era of anthropology.
It stands as the consensus for decades. But science
is a pendulum. You push it one way, eventually
someone pushes back. Always. And that push came
in 2003 from a Cambridge geneticist named AWF
Edwards. And he didn't pull any punches. He titled
his paper, Human Genetic Diversity, Lewontin's
Fallacy. Ouch. Calling a landmark study a fallacy
is academic fighting words. What was Edwards'
problem with the bus ride math? Well... Importantly,
he didn't dispute the arithmetic. He agreed that
85 % of variation is within groups. He didn't
say Lewontin calculated it wrong. His problem
was with how Lewontin looked at the data points
relative to each other. He argued Lewontin was
missing the correlation, right? Yes. This is
the technical crux of the deeper dive, so stick
with me here. Yeah. Lewontin looked at genes
one by one, locus by locus. He asked, does blood
type separate these groups? No. Does this enzyme
separate them? No. And then he averaged the results.
Okay. So he looked at them in isolation. Right.
Edward said, sure, if you look at them individually,
the overlap is huge. But if you look at the correlation
between markers, the pattern, you get a completely
different answer. I need an analogy here. How
does looking at the pattern change the result?
Think of it like a medical diagnosis. If you
just look at the symptom fever, that doesn't
tell you much. The flu causes fever. An infection
causes fever. Heat stroke causes fever. Lots
of overlap. Right. If you look at cough, same
thing. You can't categorize the patient based
on one symptom. But if you look at fever plus
a specific rash plus a swollen lymph node. Exactly.
The pattern of symptoms gives you a specific
diagnosis. Edwards argued that Lewontin was looking
at the symptoms individually and saying, these
don't tell us anything. Edwards showed that if
you look at enough genetic markers simultaneously,
if you look at the pattern, the probability of
correctly classifying someone into a racial group
approaches 100%. So Edwards is saying, I can
take a DNA sample and tell you if your ancestors
came from Europe or Africa, therefore Lewontin
is wrong. He's saying that the existence of these
statistical clusters means biological race is
a valid concept and that denying it based on
the 85 % figure is a fallacy. He's saying the
buckets do exist if you just use enough data
to find them. This feels like a paradox. How
can we be 85 % identical within our groups, which
Lewontin proved, but also easily sorted into
clusters, which Edwards proved? Those two things
sound mutually exclusive. They definitely feel
that way, but they aren't. And this is where
the response from other scientists comes in to
save us. People like Jonathan Marks and Rasmus
Grenfeldt -Winder. Winder calls this two sides
of the coin. Explain that. How can both be mathematically
true? You have to realize they're answering two
fundamentally different mathematical questions.
Question A is variance partitioning. That's Lawontin.
He's asking how much of the total diversity of
the species is explained by race. And the answer
is very little. Race is a terrible explanation
for human diversity. And question B. Question
B is clustering analysis. That's Edwards. He's
asking, can I find a pattern that allows me to
sort these people into groups? And the answer
is yes. So both are true simultaneously. We are
mostly the same, but we have just enough distinct
patterns to be sorted if you look closely enough.
Exactly. And a 2007 study by David Witherspoon
actually confirmed this. They used distinct populations
and hundreds of genetic loci and found that yes,
Lewontin's observation about the distribution
of differences holds up, and yes, Edwards' ability
to classify people is also real. But, and here's
the really big but, does the ability to sort
people mean that the race label is actually important?
That is the crux of the modern debate. Biologist
Charles Roseman points out that Lewontin wasn't
claiming you couldn't sort people into piles.
He was focused on taxonomic significance. Which
means? It means, does this grouping actually
explain the biology? Look at it this way. If
I hand you a book and say, this is a red book,
does that tell you anything about the story inside?
Not at all. It just helps me put it on a shelf.
It tells me about the cover. Exactly. Edwards
proved you can shelve the books by color. Lewontin
proved that the color of the cover tells you
almost nothing about the content. The story,
the genetic variation that determines your health,
your personality, your potential? is overwhelmingly
individual. That's a really powerful distinction.
Just because you can categorize something doesn't
mean the category is the most important thing
about it. Correct. And this is exactly where
the modern context gets messy, because this nuance,
this idea that, yes, we can cluster, but no,
it doesn't explain much, is often totally lost
in today's culture wars. Right. We saw this in
the sources about social media. The term Lewontin's
fallacy has apparently seen a huge resurgence
online 50 years later. It has. Geneticists Jedediah
Carlson and Kelly Harris actually did some research
on this. They noted that far -right and white
nationalist accounts on Twitter frequently cite
Lewontin's fallacy as a rhetorical device. And
we're not taking sides here just reporting what
the researchers found. These groups use Edwards'
critique to dismiss scientific arguments against
biological race. Exactly. They're grabbing Edwards'
clustering argument and using it to say, see?
Science says race is real and deep and fundamental.
They're ignoring the other side of the coin.
The fact that the cluster only accounts for a
tiny 6 .3 % of our actual biology. They are mistaking
a sorting mechanism for a deep biological divide.
They're pretending the book cover is the story.
It's fascinating how a highly specific statistical
critique from 2003 is being cited by people who,
let's be honest, probably haven't read the original
1972 paper or Edwards paper, for that matter.
It is. But despite all the Internet noise, the
scientific consensus has largely held firm. Countless
subsequent studies, even with modern full DNA
sequencing, have confirmed Lewontin's main finding.
The vast majority of human difference is individual.
Right. The Royal Society even published a special
issue in 2022 celebrating the 50th anniversary
of Lawontin's paper. It cemented its status as
a landmark study. The experts generally agree
that Edwards had a valid mathematical point about
clustering, but Lawontin was right about the
big picture. We are an overwhelmingly mixed and
shallowly divided species. It really changes
how you look at the person standing next to you.
If the science holds up, the stranger isn't actually
that strange. It should change how we see everyone.
Lewontin's math forces you to confront a really
weird reality. If you needed a kidney match or
a blood transfusion, your neighbor, who looks
just like you, might be a worse match than someone
from the complete opposite side of the planet.
Because the genes that determine those internal
things aren't the ones that code for skin color
or eye shape. Right. We obsess over the genes
we can see. The paint job, so to speak. But the
engine, the transmission, the wiring, that stuff
varies wildly from person to person, completely,
regardless of where they are from. It suggests
that our social intuition is basically just lying
to us. We see different faces and our brain immediately
says different category, but the DNA says rounding
error. It's a classic case of our eyes tricking
our brains. We are highly visual creatures, so
we over -index on visual differences. Laurentin
used math to strip away that visual bias and
show us the raw data. Thinking back to that bus
ride, it's amazing that he did this with a pencil
and a log table. But I'm mostly struck by the
philosophical weight of it. He wasn't just doing
sums. He was dissolving boundaries. He was. And
I think that's why this paper still matters so
much today. We live in a world that is obsessed
with putting people into boxes. It's efficient.
It makes data processing easy. It makes politics
easy. Us versus them is the oldest story in the
book. It's comforting to have a team. But biology
is telling us that the U .S. is actually incredibly
diverse and the them is mostly just us with a
slightly different tan. So here is a provocative
thought to leave you with as we wrap up this
deep dive. We spend so much energy, political
capital and social angst focusing on the differences
between these global groups. We build walls,
both real and metaphorical, based on that 6 .3
percent of difference. Meanwhile, we completely
ignore the 85 percent. Exactly. If 85 % of what
makes you biologically unique is found right
there in your own local community, within your
own so -called group, why do we continue to prioritize
the tiny fraction of differences that separate
us globally? Why is the label on the box more
important to us than the contents? Science can
give us the numbers, but it can't answer that
question for us. That one is on us to figure
out. A massive thank you to you, the listener,
for joining us on this deep dive into the math
of who we really are. It's a pleasure to unpack
this. Keep questioning the categories. We'll
see you next time.