Race and Human Evolution by Milford Wolpoff and
Rachel Caspari, Simon & Schuster, USA, $125, ISBN 0 684 81013
1

SCIENCE is fiercely competitive. 快猫短视频s compete, among other things, for
priority, for recognition by their peers and for scarce resources. The sense
that science is like any other competitive game, with winners and losers, is one
of the reasons why scientists, and scientific controversies, become the objects
of public interest.

The problem is that science rarely benefits from the limelight. The arguments
of the protagonists have to be reduced to simple propositions, and unless this
is done with skill, important nuances of the rival interpretations are lost in
the process. Add to this the difficulty of establishing the status of the rival
hypotheses and it is not surprising that the public perceives that the 鈥渨inner鈥�
must have the 鈥渃orrect鈥� answer and the 鈥渓oser鈥� the 鈥渨rong鈥� one.

If column inches are anything to go by the current winners in the debate
about the origins of modern humans are those who see Africa as the source of
modern humanity and who estimate that this African exodus, which led to archaic
populations being replaced, took place within the past 200 000 years.

The losers are those who believe that Africa was the source of our more
distant ancestors about two million years ago, but who claim that human
evolution has been 鈥減olycentric鈥� since then, and has been determined by a
balance between regional continuity and the exchange of genes between regions.
This scenario accepts that Africa played a part in shaping modern humanity, but
denies that it is the exclusive source of modern human populations.

The 鈥淥ut of Africa鈥� hypothesis has been widely publicised and espoused, both
by its supporters and by commentators.

So it is refreshing that in Race and Human Evolution, Milford
Wolpoff and Rachel Caspari set the 鈥渕ultiregional鈥� interpretation in historical
context and correct some basic misunderstandings about it. Wolpoff, the main
protagonist of the polycentric approach, and Caspari take a scholarly and
measured approach to the topic, making an important contribution to our
understanding of the historical context of the study of modern human origins.
Partisan it may be, but no more so than contributions from those on the other
side of the debate.

The case for a recent African origin for modern humans rests on three lines
of evidence. The first two, the palaeontological and the archaeological, come
respectively from the fossil evidence of our ancestors and from the stone and
other artefacts that they left behind. The third strand is based on the
differences in the DNA of contemporary modern humans.

The assumption made by the palaeontologists is that the best evidence for
鈥渕odern humanness鈥� is the appearance of the bones. Agreement has to be reached
about the features that need to be present in the skull and postcranium to judge
a skeleton to be that of a modern human, and not one of the more archaic
variants of Homo. Then, if such bones are consistently found at earlier
sites in one region rather than in all the others, that region becomes a
reasonable candidate for the source of modern humans.

The problems with using this line of argument are threefold. First, not all
modern humans look the same. Secondly, there is dispute about the modernity of
the material from the two African sites, Border Cave and Klasies River Mouth,
that are said to provide the best evidence for early modern humans in Africa.
Lastly, the reliability of the early dates for these two sites is in
question.

The archaeological evidence suffers from similar drawbacks. What activities
not undertaken by premodern populations can be said to be cardinal components of
the behavioural repertoire of modern humans? Finely crafted blades and harpoons
have been used as surrogates for modern human behaviour, and early dates for
their first appearance in Africa have bolstered the contention that it is the
continent which harbours the earliest sound evidence for hunting as opposed to
opportunistic scavenging. In other regions, the links between innovative
behaviour and a modern human-like morphology are far from clear.

Finally, what of the DNA evidence? Mitochondria are small organelles
suspended in the cytoplasm of cells. Their DNA evolves much faster than that of
the nucleus. Because the cytoplasm of each fertilised egg comes exclusively from
the mother, mitochondrial DNA (mtDNA) is inherited via the maternal line. Early
experiments indicated that there was more diversity in the mtDNA of Africans
than in any other regional population. On the assumption that this diversity was
due to mutations that were not under any selective influences, the most
reasonable explanation was that the African population had differentiated before
any of the others.

For some time these results, together with more recent and complementary
evidence from the Y chromosome, were thought to have been the final nail in the
coffin of the multiregional hypothesis. However, the latter lives on because a
recent African ancestry is not the only explanation compatible with the
evidence. Africa has very limited connections with other land masses and this
might explain some of the insularity of its human mitochondrial genome, as could
so-called 鈥渂ottlenecks鈥�, which are periods when the population levels fall below
critical values. Likewise, there is evidence that mtDNA may have been influenced
by selection. Lastly, it is by no means certain that 鈥済ene trees鈥� are the same
as population trees.

As you might expect from a book written in support of the multiregional
hypothesis, Wolpoff and Caspari point to all the weaknesses of the Out of Africa
scenario, but they do so in a way that would be difficult to take exception to.
However, the bulk of the book is an attempt, and a successful one at that, to
correct what they see as a widespread misunderstanding of the polycentric
interpretation. In so doing, they have a good stab at explaining why the
hypothesis has touched several raw nerves sociopolitically speaking.

As you might expect, the authors take exception to being lumped with racial
typologists from this century and the last. They argue that this situation would
not have arisen if their colleagues had been familiar with the original
literature. In short, they object to being lumped with Carleton Coon鈥檚
explicitly racial interpretation of modern human variation.

The heart of the book is a scholarly review of the 鈥減olygenetic鈥�
interpretation of modern human variability which suggests that modern racial
differences have a long evolutionary history. It explores the scientific
antecedents of Franz Weidenreich, the describer of Peking Man, whose views are
widely branded as being polygenetic. Wolpoff and Caspari point out that
Weidenreich had never intended to imply that regional variants of modern humans
were races that had been distinct for hundreds of thousands of years. With some
justification, they claim that Weidenreich鈥檚 writings and illustrations had made
this clear and they suggest that his views had not just been misunderstood, but
that they had been almost deliberately confused with the overtly 鈥減olygenetic鈥�
interpretation that had been adopted by Earnest, Hooton, an influential Harvard
anthropologist.

Race and Human Evolution deserves to be read by all those who are
committed to deepening their understanding of modern human evolutionary history
and who are prepared to approach the problem with an open mind.

We are inclined to down-play such regional diversity for the good reason that experience has shown that peaceful coexistence and cooperation between peoples are more likely if we emphasise the similarities between regional human populations than if we dwell on the differences. Politically, this emphasis may be right and proper, but it should not prevent biologists from using the nature and extent of modern human diversity as a means of investigating human evolutionary history.

The earliest attempts to study the nature of the differences between regional populations of modern humans were made early in the 19th century. They were concentrated on comparing the external appearance of individuals from different geographical regions, and the first classifications were based on head shape. At the time, the use of phenotypes to recover what Darwin called 鈥渢he perfect pedigree of Mankind鈥� was understandable. But once the genetic basis of inheritance was understood, it became apparent that the classical phenotype was a crude and relatively unreliable way to recover information about the relationships between population groups.

Armed with the knowledge that genes can exist in different versions (alleles), that these can be combined in a predictable number of genotypes, and with the realisation that many of these different genotypes are reliably reflected as differences in the phenotype (polymorphisms) at the molecular level, scientists began to compare populations by examining the nature of their molecules instead of the shapes of their heads. Subsequently, once the genetic code had been cracked, this new 鈥渕olecular anthropology鈥� was upstaged by the ability to make direct comparisons between the genomes of samples taken from different regional populations.

One of the benefits of the successful completion of the human genome project will be the ability to compare populations across the totality of the genome and not just for the relatively random data set that presently exists. There is an urgency about this work, for in many parts of the world social interactions between regional aboriginal populations and immigrants are rapidly obscuring the nature of the aboriginal genotypes.

This book is a magisterial survey of what is known about the distribution of human genes. It is the product of a long-standing and scientifically distinguished collaboration between the authors. Their premise is that the geographical distributions of human genes are important clues from which it is possible to reconstruct the recent evolutionary history of humankind. What is so refreshing about this book is the willingness of the authors to consider nongenetic as well as genetic evidence. They have made particularly effective use of the prehistoric geographical distribution of languages as an additional source of information about the origin and subsequent dispersal of modern human populations.

The authors begin with an admirably clear exposition of the background science and the data upon which the group鈥檚 researches are based. The database is a formidable one, consisting as it does of 76 676 gene frequencies observed in 6633 discrete population samples which have 1915 different population names. The 6633 samples were initially coalesced and reduced to 491 and then further condensed to a mere 42 populations.

The authors make it clear that these are not conventional 鈥渞acial鈥� samples. They eschewed any of the 鈥渞acial鈥� categories that have been suggested at one time or another, for the sensible and simple reason that while 鈥渢here is no doubt that there is only one human species, there are clearly no objective reasons for stopping at any particular level of taxonomic splitting鈥�. If races were meant to correspond to the boundaries of the major centres of modern human genetic variation then they should be abandoned as categories with any useful biological meaning, if only because Richard Lewontin, and many others, have demonstrated that the vast majority of modern human genetic variation occurs within, and not between, 鈥渞acial鈥� groups.

The next section presents a summary of the picture of population relationships that has emerged from previous studies based on smaller samples of polymorphisms than have been assembled in this study. It also surveys the results of the authors鈥� and other people鈥檚 analyses of DNA data including their own collection of DNA polymorphisms of nuclear genes made in collaboration with colleagues from Yale.

In brief, while the results of Howell鈥檚 careful studies of regional samples of phenotypic data taken on the cranium suggested that the major cline of variation corresponded to latitude, with close links between Africans and Australians, the first analyses of the genetic data suggested otherwise. The African samples form a tight cluster with European, Asian, Australian, while the New World samples were progressively more distant. The authors then provide wide-ranging reviews of the geographical context, the prehistory and the linguistic characteristics of the modern human populations in the five major geographical regions.

At the heart of the book are the data, presented as gene maps for the 128 alleles that relate to 49 gene markers, or polymorphisms. The main analyses are presented as average linking trees for both the full 42 population categories, and nine 鈥渟uperregional鈥� samples. All these analyses, together with a variety of 鈥渂ootstrap鈥� sampling simulations, point to the robustness of the conclusion that the earliest major population split recorded by these data was when a non-African population separated from an ancestral African population.

Of course, this could have occurred as long as 1 million years ago, or even longer, but if reasonable assumptions are made about the likely divergence time of the human lineage from that leading to the chimpanzees, then this initial fission of the modern human population is likely to have been within the last 200 000 years. In essence, these data support an African origin for modern humans.

Impressive as these data are, they only take us a little way back into human evolutionary history. And unless we are one day lucky enough to glean equivalent genetic information from the fossil record, we will have to rely on nongenetic methods to reconstruct the relationships between the extinct species of hominid that preceded us, but which nevertheless existed for more than 95 per cent of the time since the split with the apes.

We will, in fact, have to use exactly the kind of phenetic information which has been proved 鈥� by these elegant genetic studies 鈥� to give misleading results about recent human evolutionary history. So what conclusions should we draw from this? These results are chastening for, but do not spell the demise of, hominid palaeontology. Instead, they can be used to improve our efforts to delineate phenetic resemblances that are more likely to be reliable indicators of phylogenetic history.

This book is a milestone in the pursuit of human evolutionary history. It combines scholarship with excellent science and sets a daunting standard for those who take up the challenge of continuing the search for a reliable human phylogeny, using the diversity which presently exists within modern human genotypes.

Advances in molecular biology are also giving us clues about the later
stages of our evolution, as well as a picture of what we should expect to see
at the beginning of human evolutionary history. The close similarities between
the genetic codes of modern humans and the chimpanzees and gorillas have
served to confirm and reinforce the strength of the links between human
prehistory and the evolutionary history of the African apes.

Likewise, any proposed scheme for the closing stages of the evolution of
Homo sapiens has to accommodate the relatively small amounts of genetic
variation that have accumulated within the mitochondrial genome of modern
human populations. The small scale of these differences points to a relatively
recent differentiation of modern humans.

Human origins continue to spark widespread interest, but as the methods
used by palaeobiologists become more sophisticated, it is important that
public understanding keeps pace with advances in our knowledge. Richard
Leakey鈥檚 contribution to the Science Masters series achieves a high standard
of popular science writing. Instead of attempting a comprehensive review of
all the nooks and crannies of human prehistory, he opts for chronicling the
most direct 鈥渞oute鈥� between the earliest hominids and modern humans, H.
sapiens. The advantage of this strategy is that the evidence and concepts are
shorn of many of their ambiguities; the disadvantage is that it could present
a story which is unrealistically simple. It is to Leakey鈥檚 credit that he
manages to avoid this pitfall, and his account catches the sense of what has
been achieved, while drawing the reader鈥檚 attention to those areas where our
understanding is uncertain.

Among the several achievements of this book is the successful integration
of discussions about structure and behaviour. The section on the evolution of
the human brain succeeds particularly well. It sets out the rival hypotheses
explaining which selection pressures operated to sustain the increase in brain
size which is so evident in the later stages of evolution within the genus
Homo. This is, however, a part of the jigsaw that is almost certainly more
complex, and thus more interesting, than the picture Leakey paints for his
readers. The large size of the brain is such a potent icon of humanity that we
are reluctant to consider that brain enlargement may have occurred in more
than one lineage of early hominids. If this is the case, which seems likely,
then it has implications for the emergence of language and other associated
skills.

In the main, the book sensibly concentrates on that part of the evolution
of Homo that is, at least taxonomically, less contentious than the earlier
stages. But, because the text tells us relatively little about the bodies and
habits of the precursors of Homo erectus, the extent of the evolutionary
change, which is so dramatically documented by the skeleton of a young male H.
erectus recovered from the west side of Lake Turkana in Kenya, will probably
not be fully appreciated by the reader. For all the apparent modernity of the
postcranial skeleton of early African H. erectus, its relative brain size
shows little advance over that of earlier forms of Homo. Once the morphology
of H. erectus became established a little less than 2 million years ago, brain
size apparently remained relatively static for more than a million years.

It is extremely doubtful that the increase in absolute brain size which
occurs in archaic H. sapiens is related to a simple increase in overall body
size. We have to look for either a trigger for this increase in brain size, or
the release of a constraint that was operating in the early Homo species to
limit brain size. Changes in systems as apparently diverse as socialisation
and diet have been canvassed as the cause of the increase in brain size. The
explanation, or explanations, for the evolution of the human brain has been,
and continues to be, the most sought-after prize in human evolutionary
studies.

This book is a reliable and accessible source of information about the
achievements of, and the challenges facing, those who study the biology of our
ancestors. It is challenging without being intimidating. Likewise, it manages
to convey the excitement of the search for human origins without trivialising
it. If this standard is maintained, the Science Masters series looks set to
play a major role in the responsible popularisation of science.

Those who use the letter pages of newspapers to rail at the conduct of a
section of contemporary society 鈥� usually football hooligans or rowdy
parliamentarians frequently describe the objects of their ire as 鈥榖ehaving
no better than Neanderthals鈥�. In doing so the irate correspondents hope to
convey an image of conduct which is, at the very least, unacceptable,
uncouth and uncivilised. 鈥楴eanderthal鈥� is a remarkably convenient term of
abuse. It refers to a group which is extinct, racially neutral and which has
no pressure groups to guard its interests. My grandfather told me, among
many other things, never to use long words that I did not understand. My
guess is that most of those who ascribe to Neanderthals all that is brutish
and boorish would have failed my grandfather鈥檚 simple vocabulary test.

Joachim Neander was a 17th-century verse writer who lived his short life,
just thirty years, not far from Dusseldorf in the country we now call
Germany. His work is famous and well loved, not as poetry, but as the text
of several hymns; the best-known, 鈥楶raise to the Lord, the Almighty, the
King of Creation鈥� has survived various revisions of Hymns Ancient and Modern
and is also included in the English Hymnal. His fame in his native land was
such that a tranquil valley that he frequented was given his name, hence
Neandertal, or Neander鈥檚 valley.

The industrial revolution shattered the tranquillity of Neander鈥檚 valley,
opencast mining transforming its wooded slopes into a series of ugly pits
and quarries. It was in this landscape, the antithesis of the environment
that had inspired Neander鈥檚 writing, that the bones of a skeleton were found
in 1856. They were handed by the quarry foreman to the local schoolmaster,
Johan Fuhlrott, and thence referred to Hermann Schaaffhausen, the professor
of anatomy at Bonn University. Fuhlrott and Schaaffhausen presented the
fossils to a meeting in Bonn in 1857, reporting that the skull cap bore
heavy ridges above the eye sockets, lacked a prominent forehead and sported
an impressive crest at the back to anchor the neck muscles.

It took four years for the finds to be considered seriously by natural
historians in Britain. They were brought to scientific attention by George
Busk who was a polymath by any standards 鈥� to my knowledge he is the only
president of the Royal College of Surgeons of England to have given his name
to a group of invertebrates, the Buskia. Surgery in the 1860s clearly did
not make the demands on time that it does today. Busk recalled that a skull
with similar features had been found in 1848 in Gibraltar and had been
referred to the Museum of the College of Surgeons by its discoverer, Captain
Broome.

These remains, along with skulls found at Engis in Belgium even earlier,
thus formed the basis of our knowledge of what we now call the Neanderthals.
Similar looking remains have since been found at sites in Europe from
Pontnewydd in Wales across to Shanidar in the Near East and Teshik-Tash in
Uzbekistan, Western Asia. The earliest evidence of Neanderthal-like
creatures comes from fossils recovered from a cave in Spain which may date
to 400 000 ago, but Neanderthals are best known from sites that date from
between 80 000 to 30 000 years ago.

Their skeletons tell us that apart from a few quirky differences, mostly to
do with being heavily muscled, Neanderthals were built much like modern
humans. Their tool kits were basic, but probably effective for all but the
most complex tasks. They apparently cared for injured companions, buried
their dead and manufactured primitive art objects. They managed to occupy
climates and landscapes that most of us would venture to inhabit only with
the aid of down-filled jackets and reliable sources of transport and
shelter. What have these intrepid forebears done to deserve their reputation
for brutality and stupidity?

In The Neandertals, the internationally respected scholar Eric Trinkaus and
Pat Shipman, a well-qualified and accomplished science journalist, have
documented the history of Neanderthal research and have shown that
Neanderthals have hardly ever been interpreted objectively. They have
suffered a range of scientific and moral abuse, most of which can be
understood in its historical context. It would be heartening to report that
their suffering is at an end, but Trinkaus and Shipman remind us that
Neanderthal evidence is currently being cited in their support by proponents
of both the main models for the origins of modern humans, namely the 鈥極ut of
Africa鈥� and multiregional hypotheses, (See Review, 12 June.)

The two authors have evidently approached their task with diligence and
thoroughness. If the book has a failing it is that it gives the reader
little help to see the wood from the trees. No fact about the dramatis
personae is too trivial and, before reaching the end of the book, I became
unreasonably irritated by the authors鈥� descriptions of scientists, which
are accorded as much prominence as carefully researched information about
their science. Was it important to be told of one scientist that 鈥榟e had
obviously inherited his father鈥檚 intensity and ambition and his mother鈥檚
emotionality, along with a head of thick, dark hair, piercing eyes and a
sensitive, full-lipped face鈥�?

Apart from my lingering uncertainty about whether Ales Hrdlicka鈥檚 facial
features are maternally or paternally derived, this kind of pen portrait
does little to help to advance the authors鈥� welcome attempt to chronicle and
explain the history of Neanderthal-related science.

The Neandertals is no casual holiday read, but it is a fund of
well-researched information about how prehistorians have grappled with
interpreting an intriguing collection of human fossil remains. The full
significance of that collection still eludes us, but the more objective
methods now being deployed, both to establish the Neanderthals鈥� place in
human prehistory and to understand their diet, locomotion, social system and
life history, may signal a new and more hopeful phase in the research of
this distinctive group of hominids.

Bernard Wood is head of the Department of Human Anatomy and Cell Biology at
the University of Liverpool.