Who are we, and where did we come from? Scientists studying the origin of modern humans, Homo sapiens, keep reaching deeper in time to answer those questions — toward the last common ancestor of great apes and humans, then forward to the emergence of people more and more like us in body and behavior.
Their research is advancing on three
fronts. Fossils of skulls and bones expose anatomical changes. Genetics reveals
the timing and place of the Eve of modern humans.
And archaeology turns up ancient artifacts
reflecting abstract and creative thought, and a growing self-awareness. Just
last month, researchers made the startling announcement that Stone Age paintings in Spanish caves were much older
than previously thought,
from a time when Neanderthals were still alive.
To help make sense of this cascade of
new information, a leading authority on modern human evolution — the British
paleoanthropologist Chris Stringer — recently sat for an interview in New York
that ranged across many recent developments: the evidence of interbreeding
between Neanderthals and Homo sapiens; the puzzling extinct species of little
people nicknamed the hobbits; and the implications of a girl’s 40,000-year-old
pinkie finger found in a Siberian cave.
Dr. Stringer, an animated man of 64,
is an anthropologist at the Natural History Museum in London and a fellow of
the Royal Society. But he belies the image of a don: He showed up for our
interview wearing a T-shirt and jeans, looking as if he had just come in from
the field.
A condensed and edited version of our
conversation follows. In it and in a new book, he describes a new wrinkle to
the hypothesis of a recent African origin of modern Homo sapiens. His ideas may
light up more debate in a contentious science.
First of all, would
you explain the title of your new book?
Yes, the title is “Lone Survivors: How We Came to Be the Only Humans on
Earth.” And this comes
from the fact that if we went back 100,000 years, which is very recent,
geologically speaking, there might have been as many as six different kinds of
humans on the earth. All those other kinds have disappeared, and left us as the
sole survivors.
You wrote that in
1970, when you started doing research in this field, the origin of modern
humans was hardly recognized as a topic worthy of study in science. What has
changed since then?
It’s been a fantastic time to be
involved in the field, and even when I was writing this book in the last two
years, I had to regularly go back and rewrite things I thought I’d finished
with, because new developments were coming up all the time. In 1970, for some
people, there was no single origin of modern humans: We evolved globally, all
over the world. There was a view that in the different regions an earlier
species, Homo erectus, evolved relatively seamlessly to modern humans. This
idea was known as multiregionalism.
The argument went that we remained
one species throughout that evolutionary process, because there was
interbreeding among the different populations. It meant that the Neanderthals
in Europe, for example, would be the ancestors of modern Europeans; Homo erectus
in China would be the ancestor of modern Asians. And Java Man would be a
distant ancestor of modern Australian aboriginal populations.
What we have seen since then is a
growth in the fossil record, in our ability to date that record and to CT-scan
fossils and get minute details out of them. DNA studies have had a huge impact
on our field. We now have the genomes of Neanderthals and of these strange
people in Siberia called the Denisovans.
Speaking of DNA,
what about the African Eve? This established an approximate date for the
genetic origin of modern humans, in Africa. As a leading advocate of the recent
African origin, in contrast to the multiregional model, did you believe this
settled the debate?
To be honest, it’s not been totally
resolved, but the Mitochondrial Eve publication of 1987 was a key moment. Up to
then, a few of us were arguing for a recent African origin from the fossil and
archaeological evidence. But the evidence was pretty skimpy, and the majority
opinion was against our view.
When this new genetic technique
appeared, it seemed to give clarity to the picture. Here was an independent bit
of data, from our mitochondrial DNA, inherited through females, suggesting we
originated, all of us, all over the world, from a single ancestral population
that lived in Africa maybe 200,000 years ago.
I came to this conclusion gradually,
starting with the Neanderthals. They were the best-known ancient humans, and
there was a view that they were our ancestors. I tested that model in my Ph.D.
research, and I concluded the Neanderthals did not make good ancestors of
modern humans, even in Europe, where we had the best data. So gradually my
search moved from one region to another, to see where the evidence best fitted
the idea of our origins.
It turned out that Africa was the
place that had the oldest fossils of modern humans. Africa, for me, was the
only place that showed a transition from archaic to modern humans.
In your book you
propose that there was not one place in Africa where modern humans originated.
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