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

To the memory of lost family Tony and David, and lost colleagues Bill, Clark, and Roger

Contents

Illustrations

Copyright information is given in parentheses

( John Reader )

( Chris Stringer )

( The Boxgrove Project )

( John Reader )

( Natural History Museum, London )

( Chris Stringer/Rosemary Lee )

( David Hart )

( Gnter Bruer/Chris Stringer )

( Natural History Museum, London )

( Natural History Museum, London )

( Chris Stringer )

( The Boxgrove Project )

( John Reader )

( Chris Stringer/Muse de lHomme, Paris )

( Erik Trinkaus )

( courtesy and Tim White )

( courtesy and Tim White )

( courtesy and Tim White )

( Chris Stringer )

( Juraj Liptk/University of Tbingen ); flute ( Hilde Jensen/ University of Tbingen ); Venus ( Hilde Jensen/University of Tbingen ); waterbird ( Juraj Liptk/University of Tbingen )

( Maria Malina/ University of Tbingen )

( Chris Henshilwood )

( Chris Henshilwood )

( Chris Henshilwood )

( Francesco dErrico )

( Chris Henshilwood )

( Chris Henshilwood )

( replica, Chris Stringer )

( Francesco dErrico and Marie Soressi )

( Mark Stoneking )

( Chris Stringer )

( Susan Carvalho )

( Chris Stringer )

( Chris Stringer )

( Chris Stringer )

( Chris Stringer )

( Colin Groves )

( Michael Day )

( Chris Stringer )

( Natural History Museum, London )

( Chris Stringer )

( Chris Stringer )

Introduction

We have just celebrated the 150th anniversary of the publication of Charles Darwins On the Origin of Species and his two hundredth birthday, and evolution by natural selection is now widely accepted. But what do we know about the origin of our own species, Homo sapiens ? Despite the fascinating and growing record of very ancient prehuman fossils, one topic has dominated recent scientific and popular discussion about evolution: our own origins. While it is generally agreed that Africa was the homeland of our earliest human ancestors, a fierce debate continues about whether it was also the ultimate place of origin of our own species, and of everything that we consider typical of our species, such as language, art, and complex technology. Originally centered on the fossil record, the debate has grown to encompass archaeological and genetic data, and the latter have become increasingly significant, now even including DNA from Neanderthal fossils. Yet much of these new data and the discussions surrounding them are buried in highly technical presentations, scattered in specialist journals and books, so it is difficult for a general readership, however informed, to get an accessible overview.

In this book I want to try and provide a comprehensivebut comprehensibleaccount of the origin of our species from my position in these debates over the last thirty years or so. Ive worked at the Natural History Museum in London even longer than that, and the idea that I could have ended up there, studying our origins, was a boyhood dream which I never thought would actually come to pass, given my relatively humble origins in the cockney area of east London. But with supportive parents and foster parents and some teachers who encouraged me along the way, I started to realize that dream when, at age eighteen, I made a last-minute switch from studying medicine to taking a degree in anthropology. It was a gamble that paid off when I was accepted into the Ph.D. program at Bristol University in 1970 to study my favorite fossil peoplethe Neanderthalsand then even that was capped by the offer of a job in the Palaeontology Department at the Natural History Museum in London, in 1973.

It has been such an exciting time to be working in this field, with wonderful new fossil finds, but also the arrival of a host of new techniques to date and study them. I hope my book will make every reader think about what it means to be human, and change his or her perceptions about our originswriting it has certainly changed some of mine!

I regularly give talks on human evolution and receive hundreds of inquiries on this topic every year from the media and the public. The same questions recur time and again, and in this book I will try to answer them. These questions include:

1. What are the big questions in the debate about our origins?

2. How can we define modern humans, and how can we recognize our beginnings in the fossil and archaeological record?

3. How can we accurately date fossils, including ones beyond the range of radiocarbon dating?

4. What do the genetic data really tell us about our origins, and were our origins solely in Africa?

5. Are modern humans a distinct species from ancient people such as the Neanderthals?

6. How can we recognize modern humans behaviorally, and were traits such as complex language and art unique to modern humans?

7. What contact did our ancestors have with people like the Neanderthals, and were we the cause of their extinction?

8. Do archaic features in modern human fossils and genes outside Africa indicate hybridization?

9. What does DNA tell us about the Neanderthals and possible interbreeding with modern humans?

10. What can we learn from a complete Neanderthal genome, and will we ever clone a Neanderthal?

11. What forces shaped the origins of modern humanswere they climatic, dietary, social, or even volcanic?

12. What drove the dispersals of modern humans from Africa, and how did our species spread over the globe?

13. How did regional (racial) features evolve, and how significant are they?

14. What was the Hobbit of the island of Flores, and how was it related to us?

15. Has human evolution stopped, or are we still evolving?

16. What can we expect from future research on our origins?

It is now over twenty years since the publication of the seminal Nature paper Mitochondrial DNA and Human Evolution by Rebecca Cann, Mark Stoneking, and Allan Wilson that put modern human origins and Mitochondrial Eve on the front pages of newspapers and journals all over the world for the first time. Not only did that paper focus attention on the evolution of our own species, but it also led to a fundamental reformulation of scientific arguments about the way that we look at our own origins. A year after that publication, I wrote the paper Genetic and Fossil Evidence for the Origin of Modern Humans for the journal Science with my colleague Peter Andrews, which set out the contrasting models of modern human origins that have dominated debate ever since: the Recent African Origin model and the Multiregional Evolution model. Later in the book we will see how these models have fared in the face of many new discoveries, but in the first chapter I will look at some of the big questions of modern human origins, including what diagnoses our species, what the recent debates are all about, and how the different models lay out expectations of what we should find in the record of modern human evolution, from fossils, archaeology, and genetics.

The Big Questions

It is barely 150 years since Charles Darwin and Alfred Russel Wallace presented their ideas on evolution to the world. A year later, in 1859, Darwin was to publish one of the most famous of all books, On the Origin of Species . Then, the first fossil human finds were only beginning to be recognized, and paleontology and archaeology were still in their infancy. Now, there is a rich and ever-growing record from Africa, Asia, and Europe, and I have been privileged to work in one of the most exciting eras for discoveries about our origins. There have been highly significant fossil finds, of course, but there have also been remarkable scientific breakthroughs in the amount of information we can extract from those finds. In this first chapter I will outline the evidence that has been used to reconstruct where our species originated, and the very different views that have developed, including my own. There are in fact two origins for modern human features that we need to consider. Here, I will talk about our species in terms of the physical features we humans share today, for example, a slender skeleton compared to our more robust predecessors, a higher and rounder braincase, smaller brow ridges, and a prominent chin. But there are also the characteristics that distinguish different geographic populations todaythe regional or racial characteristics, such as the more projecting nose of many Europeans, or the flatter face of most Orientals. I will discuss their quite different origins later in the book.