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DAVID REICH: Well I was always interested in history, actually.
When I was in college I actually started in sociology or history
– history and sociology as my major. I actually switched to
sort of hard sciences in my third year because I sort of
realized I also was sort of interested in those things. But
I was actually always interested in history as well. When I
moved into sort of hard science and into biology, I kind of left
that history behind but I sort of rediscovered in graduate
school. So what happened was I was looking for a laboratory to
work in in Statistical Genetics or statistics or math or physics
or something like that or biology, and I was wandering
around laboratories and there was one laboratory that was
doing Human History as learned from genetic data which I had
never heard about before and didn't know that you could
actually do, but I was sort of interested in history and, I
actually wasn't even really in a PHD program yet, so I thought
this would be something fun to do for a couple of years and
actually turned into what I continue to do now.
Yeah, the best piece of advice I ever received was probably the
same piece of advice I got from my advisor at the time and also
from my mother, which was I had an amazing result, which was
that after human and chimpanzees separated, chimpanzees are our
most closest living relatives. There was then hybridization
between gorilla and human ancestors that led to our
lineage today. So that was a very exciting and interesting
result and we had strong genetic statistical evidence for it.
And so I sent – I presented a paper that was nearly finished
to my advisor and I said, "What do you think of this?" and he
said, "Wow, that's amazing, I think – I'm pretty convinced
you're right, it's – I bet that you're right, but it would be
such a career wrecker if you published this result and it
turned out to be wrong that you should check it some more."
This is the same thing my mom told me. So I then went ahead
and checked it some more, gathered some more data and it
turned out to be wrong, just a statistical fluctuation. So ever
since I've actually gathered much, much more genetic data and
try to be as convinced as possible and to address things
with multiple lines of evidence so you find one pattern but then
you actually look for other patterns that would be predicted
by that model. This is what we did with, for example, the
evidence of gene flow between the Neanderthals and the
ancestors of non-Africans. We actually supported it with
multiple lines of evidence and it's in part at least my
contribution to that, due to this sort of advice I got and
this sort of shock that I got that things actually might seem
one way, but they're actually are not always the way they
at first seem.
I was actually really interested in maps, and so we had a map of
the world next to our dinner table, breakfast table and I was
interested in projections and distortions in maps. And so I
was sort of thinking about ways – so in a map you sort of have
distorted sections of the globe depending on where the map is
trying to get a best – get the best picture and sort of I
developed this sort of map where I sort of wrote – I drew the map
of the world by hand on these little strips and I can move the
strips around to un-distort any place I wanted to. So that was
sort of my first scientific experiment and I sort of spent
a lot of time drawing maps of the world and sliding
little pieces of cardboard around to un-distort
and distort different sections.
I think it's the really freedom to sort of ask questions that
you or other people don't really know about, so it's to really
sort of figure out something that's never been known before,
and certainly in the area that I work in, there's lots and lots
of things that we don't know and we have so much more ability to
learn about them than we used to, even five years ago because
the amount of information we have access to from genome
sequencing is so much so larger. And so it's really like being
sort of a child in a candy store or something like this because
there's so many unanswered questions and the data are
finally in place to really answer them. So we could all
answer these questions about human history and how people
relate to each other that we really couldn't answer before
and really areas that have been really struggled with before
that by other fields like archeology or fossil science.
We can't answer all the questions they struggled
with but some of them we can answer now with
these genetic information.
I think the thing you really want to do is to always ask
yourself whenever you hear something like on TV, or on the
radio, or in a newspaper article, always think like why
is that wrong or how could that be wrong? And always be
questioning what you hear or is there something else that's
going on here? So I think that that's what you always have to
cultivate, and I think that sort of the best scientists I know
are always sort of thinking in a little bit of contradictory way
when people talk to them, what's wrong about that?
I think there's lots of different areas where my
particular research sort of adds value to – sort of has a social
benefit. I think a lot of other people's research also has a
social benefit. Part of my research is medical and so
there's a direct impact on finding genes that cause
disease. I study mixture between human populations and a
lot of human populations like Latinos and African Americans
and South Asians are mixed populations and you need to
understand that history of mixture in order to find the
genes that affect risk for disease in those populations.
But the other thing is really pushing knowledge forward and
answering things that we didn't know about before and I actually
think that that's one of the most important things that as a
society we do which is we have a group of people, preferably lots
and lots of people who are really asking about fundamental
things like the nature of the universe, and the nature of our
biology, and the nature of our history that we didn't really
know before. And so we get to ask these questions that we
really didn't know about before and address them and I think
that's very valuable.
I think, probably, the person who's been most influential to
me and I've had a few very important role models, but
I think that, probably the person's who's been most
influential on me, it's not someone I've really met. I
actually have met him two years ago, but someone named Luca
Cavalli-Sforza. So Luca Cavalli-Sforza is sort of
the person who really started this field of population,
learning about history from population variation, for
genetic variation, and he's an Italian researcher. He's spent
most of his life in the United States, his working, his
research life, but he's really a great scientist. But I've had
other really important influences. For example, my
main collaborator is a statistician, Nick Patterson,
who I work with all the time and this is his third career. He
was a cryptographer; he broke codes for the U.S. and the
British governments, and he was a hedge fund scientist, and he
really loves thinking of data and trying to get to the bottom
of things and that's been a great influence on me.
So, I think, that's what's very interesting about the field is
really how much power we have to look – learn about things that
we didn't know about before. There's big questions about the
nature of human history; how did the people who currently exist
now, how did we get here and things that we assume are true
that actually turn out not to be true and you can see those in
the genetic data. So for example, people often think that
Europeans are a homogeneous group that's arrived in a simple
way there maybe 40,000 or 50,000 years ago based on the
archeology and just kind of sat there until they became the
Europeans they are today. But that's probably not true; the
Europeans today are a replacement population who came
in much more recently and replaced the people who were
there originally 40,000 years ago. People in Africa,
certainly very diverse, but in fact there's very deep strands
of variation in Africa. And for example, West Africans people –
the primary ancestral group of African Americans today are
actually turn out to be mixtures of very differently diverged
groups that go very deep in time. And so this is all very
interesting, also, true for East Asians. East Asians, people in
China today, are not the same people who were there from the
first time 40,000 years ago. In fact, they're a replacement
population largely that arrived there after the first people
there. So you see this history of more complex population
movements than people think at first.
I think the disk with all my data sets, I think that's
what we need.
That's an interesting question. I actually like to work in a
café sometimes and it's been a theme of my whole life working
in loud cafés with this kind of pop music going on. I never
know what they're playing but I kind of know well the current
pop music even though I don't know the artists but like –
so I like loud kind of pop-bad music all the time, playing
in the background it sort of makes me concentrate,
helps me concentrate.