Thursday, September 25, 2014

Lone Survivors: How We Came to Be the Only Humans on Earth, by Chris Stringer

Times Books/Henry Holt and Company, ISBN 9780805088915, 2012 (original publication 2011)

Where does our species come from? Who were our ancestors?

These are enduring human questions, and we are piecing the answers together out of bits of bone and stone tools and recovered DNA. Chris Stringer is one of the world's leading paleoanthropologists, and one of the leading proponents of the "Out of Africa" theory, proposing a recent African origin for Homo sapiens in eastern or southern Africa, who then expanded out of Africa, replacing the archaic humans, including Neanderthals, in the rest of  Eurasia.

Lone Survivors is an examination of the major breakthroughs of the last thirty years, with new evidence and new kinds of evidence, including the advances in recovering and analyzing DNA from ancient fossils. That evidence has, in fascinating ways, both reinforced the basic "recent African origin" hypothesis, and raised serious challenges to the idea that this origin happened in one, highly localized place.
We may have made the leap to modernity in Africa precisely because Africa is a huge and diverse continent. When one population made the transition to complex modern behavior, and the local conditions turned against them, they may have died out or moved on or slipped back to premodern levels.

But this was in Africa, and there was someplace to move on to where the environment would support the population density needed for modernity. And if the first group didn't migrate to a more promising area, there were other populations that could exploit them. Because there was a wide enough range of environments, and enough somewhat separated populations of early modern humans, eventually, that critical mass was reached, modern human behavior was here to stay, and modern humans spread out from Africa.

That's the simple summary. This is a complex and fascinating story, including not just modern and extinct human species, but the "archaic" humans whose genes are still with us in our own DNA, including Neanderthals and Denisovans.

Stringer avoids polemics, does not waste time on science deniers, and points out his own errors and mistakes over the years as readily as he does others'. His writing is clear, understandable, and informative.

There is also discussion of the most newly-discovered, and oddest, member of Genus Homo, Homo floresiensis, a.k.a. the Hobbits of the island of Flores.


An interview with Chris Stringer:

I bought this book.