Before the Dawn: Recovering the Lost History of Our Ancestors

323 Pages·2006·4.94 MB·English

by  Nicholas Wade

B E F O R E T H E D AW N

B D
E F O R E A W N
THE
R e c o v e r i n g
t h e L o s t Hi s t o r y o f
O u r A n c e s t o r s
NICHOLAS WADE
T H E P E N G U I N P R E S S N E W Y O R K 2 0 0 6
THE PENGUIN PRESS
Published by the Penguin Group
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80 Strand, London WC2R 0RL, England
First published in 2006 by The Penguin Press,
a member of Penguin Group (USA) Inc.
Copyright © Nicholas Wade, 2006
All rights reserved
Illustration credits appear on pages 299–300.
LIBRA RY OF CONGRESS CATALOGING-IN-PU BLICATION DA TA
Wade, Nicholas.
Before the dawn : recovering the lost history of our ancestors / Nicholas Wade.
p. cm.
Includes bibliographical references and index.
ISBN: 1-4295-1377-2
1. Human evolution. 2. Social evolution. I. Title.
GN281.W33 2006
599.93'8—dc22 2005055293
Designed by Kate Nichols
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Contents

1. Genetics & Genesis
1
2. Metamorphosis
12
3. First Words
35
4. Eden
51
5. Exodus
74
6. Stasis
100
7. Settlement
123
8. Sociality
139
9. Race
181
10. Language
202
11. History
233
12. Evolution
264
Notes 280
Acknowledgments 299
Credits 300
Index 302
About the Author 314

1
Genetics & Genesis

It has often and confidently been asserted, that man’s origin can never
be known: but ignorance more frequently begets confidence than does
knowledge: it is those who know little, and not those who know much,
who so positively assert that this or that problem will never be solved
by science.
CHARLES DARWIN, THE DESCENT OF MAN
TRAVEL BACK INTO THE HUMAN PAST, and the historical evidence
is plentiful enough for the first couple of hundred years, then rap-
idly diminishes. At the 5,000-year mark written records disappear
altogether, yielding to the wordless witness of archaeological sites. Going
farther back, even these become increasingly rare over the next 10,000 years,
fading almost to nothing by 15,000 years ago, the date of the first human
settlements. Before that time, people lived a nomadic existence based on
hunting and gathering. They built nothing and left behind almost nothing
of permanence, save a few stone tools and the remarkable painted caves of
Europe.
Travel on back for another 35,000 years and you will have reached the
50,000-year mark, the time when the ancestral human population was still
confined to its homeland somewhere in northeast Africa but had begun to
show the first signs of modern behavior. If this is the point at which the
modern human story begins, then written records exist for just the last 10%
of it; 90% of human history seems irretrievably lost.
Keep traveling back in time to the earliest starting point in the human
narrative, the period 5 million years ago when the ape-like creatures at the
head of the human line of descent split from those at the head of the chim-
panzee line of descent. The only physical evidence from throughout this
period, which saw the evolution from ape to human form, is a handful of
battered skulls and a few stone tools.
2 BEFORE THE DAWN
No deep understanding, it might seem, could ever be gained of these
two vanished periods, the 5 million years of human evolution and the 45,000
years of prehistory. But in the past few years an extraordinary new archive has
become available to those who study human evolution, human nature and
history. It is the record encoded in the DNA of the human genome and in
the versions of it carried by the world’s population. Geneticists have long
contributed to the study of the human past but are doing so with particular
success since the full sequence of DNA units in the genome was determined
in 2003.
Why should the human genome, specifically shaped for survival in the
present, have so much to say about the past? As the repository of hereditary
information that is in constant flux, the genome is like a document under
ceaseless revision. Its mechanism of change is such that it retains evidence
about its previous drafts and these, though not easy to interpret, provide a
record that stretches deep into the past. The genome can therefore be inter-
rogated at many different time levels. It can supply answers that reach back
more than 50,000 years to the genetic Adam, a man whose Y chromosome is
carried by all men now alive. Or it can be queried about the events of a mere
couple of centuries ago, such as whether Thomas Jefferson, the third presi-
dent of the United States, had a secret family with his slave mistress Sally
Hemings.
From Adam to Jefferson, the genome is helping researchers create a new
and far more detailed picture of human evolution, human nature and his-
tory. From the great darkness, a surprisingly full narrative is emerging. This
new narrative of the human past rests on a solid foundation laid by paleoan-
thropologists, archaeologists, anthropologists and many other specialists. It
can be called new in the sense that genetic information now contributes to
each of these traditional disciplines and is beginning to draw them together.
This book describes those aspects of human evolution, nature and pre-
history that have been illumined by genetic discoveries of the last few years.
Readers who do not follow these fields closely may be surprised at the rich-
ness of the information in the new narrative. There exists no video of how
apes slowly morphed into people, but a sequence of the salient events can
for the most part be reconstructed. There is no map that records the disper-
sal of the new humans from their ancestral homeland, but researchers can
now follow the path they took out of Africa and their migrations through the