Out of Eden: The Peopling of the World

by Oppenheimer, Stephen

  In the next chapter we shall see what those pioneers did on the North and East Asian mainland after they arrived, and how they got to those places.

  5

  THE EARLY ASIAN DIVISIONS

  WE ALL HAVE A TENDENCY to see differences. ‘Mummy, why does that person look like that?’ is a question we hear on children’s lips from an early age. So why is it that people from different parts of the world all look so different? Why are children and adults so interested in these things? To many people the issue of physical difference is loaded with that ugliest and most destructive form of human group behaviour, racism. But we get nowhere by shutting our eyes. Differences will not fade away, and open-minded enquiry should help us to understand ‘why that person looks like that’ and why differences in physical appearance can be such a sensitive issue.

  A common argument, introduced in the last chapter, is that after the various groups which are now spread over the huge Asian continent split up, they somehow drifted apart and ‘evolved’ in isolation from one another. As with the evidence for the unity of the original dispersal, there is genetic support for these ideas of isolation and change, but the archaeological and fossil support for the details of the story is less clear. The truth is that there is very little archaeological, let alone fossil evidence for where and when the ancestors of different modern Asian groups have been for most of the past 80,000 years, so, to a certain extent, any answer is speculative. Even with the uncertainty of fossil evidence, however, dates from archaeological sites, combined with knowledge of past climate and the evidence from genetic markers, do allow us to reconstruct the routes taken by the first Asians. The pioneers penetrated their vast continent from three widely separated parts of the Asian Indo-Pacific coast. The choice of those routes had profound consequences for the subsequent physical differentiation of the explorers, resulting from isolation and adaptation to new environments.

  Why is the question so fascinating – and anyway, what do we mean by ‘different’? The answer to the first is probably in our nature in that humans have evolved an extraordinary capacity for recognizing and remembering a large number of different faces. We need this skill partly because our extended social groups are large.1 They are larger, and the interactions between their members are far more complex, than those of even our nearest living relatives, the chimpanzees. We have to be able to recognize many people. Failure to identify people you should know is embarrassing and is quickly noted as a weakness.

  Along with the social advantages it provides, our ability to recognize faces enables us to classify what we see, and identify shared physical similarities within groups, and differences between one group and another. Clearly this can and does feed into our inclusive and exclusive group behaviour, and is what can lead us to discriminate against ‘outsiders’ who look ‘different’. Luckily our insight into our own innate tendency to ‘group and exclude’, and the terrible crimes against humanity that can result from organized racism, have led us to take statutory and voluntary steps to control and proscribe such behaviour. Tragically, these checks are not always successful, and old lessons of the evils of pogroms and group persecution are ignored, even by former victims of racism.

  The limited power of words

  A by-product of the fight against racism has been to render discussion of race taboo. Even the word ‘race’ itself, tainted forever by the Nazi era, is outlawed by many anthropologists as unscientific, derogatory, meaningless, and giving the misleading impression that races are discrete entities when in fact variation, gradation, and admixture occur everywhere. This is all very worthy, but the fact remains – as children are quick to notice – that people from different regions can look dramatically different from one another. In the end, proscription and regularly changing euphemisms do not help; most alternative terms for race such as ‘population’ or ‘ethnic group’ are so vague as to be just as misleading. In this book I use terms such as ‘Caucasoid’, ‘Mongoloid’, and ‘Negrito’ to describe physical types, not because they are accurate but because they have common usage. Many anthropologists will object that they are derogatory and imprecise. From Figure 5.1, readers who share this view will be able to interpret my terminology in terms of their preferred emphasis on the geographical area of indigenous populations who appear broadly related on a wide range of biological attributes.

  Figure 5.1 Table of rough terminology for ethnic groups and names/apparent racial differences.

  With my choice of terminology I am not intending to derogate people who do not look like me – on the contrary, I know that the rest of the world has a distinct advantage in not looking like me. Equally, however, I believe that politically correct euphemisms are just as imprecise and misleading as the older terms. Inevitably, a well-known word such as ‘Mongoloid’ is often useful as a shorthand description of a general physical type, but we should always remember that the ‘traditional’ terms are imprecise descriptions of a complex biological reality that varies enormously within groups as well as overlapping between populations.

  The most obvious physical difference between peoples of Eurasia is their skin colour, which tends to be darker in the sunnier tropical regions. This is no coincidence. Skin darkness, which depends on the pigment melanin, is controlled by a number of poorly understood genes and is also under evolutionary control. For those who live in tropical and subtropical regions, the risk of burns, blistering, and the likelihood of death from skin cancer induced by ultraviolet light is dramatically reduced by having dark skin. There are other, less dramatic advantages: for example, the melanin in pigmented skin allows it to radiate excess heat efficiently, as well as protecting against the destruction of folic acid, an essential vitamin. So in sunny climes, over many generations, people with dark skin live on average longer and have more successful families.2 In North Asia (i.e. Asia north of the Tibet-Qinghai Plateau and east of the Urals) and Europe there is less sun and a lower risk of skin cancer, but there is the ever-present risk of rickets, a bone disease caused by lack of sunlight that was still killing London children even at the beginning of the twentieth century. I know this because I once did research on rickets while I was based at the Royal London Hospital’s pathology department. Rickets, or osteomalacia, came back in a small way to Britain in the second half of the twentieth century, but affected the children of families from the Indian subcontinent. Part of the reason for this was their darker skin colour, which filtered out some of the already meagre sunshine.

  So there are at least two evolutionary selection forces working in concert, tending to grade skin colour according to latitude. The sun-driven change in skin and hair colour evolves over many generations. From the available genetic evidence, Africans appear always to have been under intense selective pressure to remain dark-skinned. Outside Africa, though, we can see gradations of skin and hair colour as we move from Scandinavia in the north of Europe and Siberia in the north of Asia down to Italy and Southeast Asia in the south of those regions. The darkest-skinned groups of non-Africans still tend to live in sunny and tropical countries. Clearly, if change in skin colour takes many generations, we shall sometimes find people whose recent ancestors have moved to live in sunny countries and who are still fair skinned (and vice versa). A good example is Australia, a sunny country where the majority of today’s inhabitants are pale-skinned descendants of recent immigrants. Australia has one of the world’s highest rates of skin cancer, and this has already started it on the slow evolutionary path that will eventually lead to descendants of Europeans becoming generally darker-skinned. Conversely, the first visitors to the north of Europe and Asia probably started their journeys looking very dark skinned and evolved to become paler later. Apart from exceptions such as Australia, the average skin colour around the world is thus tuned to the relative amount of ultraviolet light (Figure 5.2).3

  Since this evolutionary trend continuously affects people of all latitudes at all times, our colour may have more to say about where our ancestors lived over the past 10,00
0–20,000 years than about their genetic divergence over the previous 60,000 years. So, the skin colours of today’s people are of limited value in tracing ancient routes of migration after the African exodus. In other words, colour is not the most useful marker for the understanding of human prehistory between 80,000 and, say, 10,000 years ago. It may come as a surprise that skin colour is so evanescent, since it is the most obvious and divisive of all ‘racial’ characteristics. The key to human discriminatory behaviour is not in logic, however, but in the need to find an easily recognizable feature or pretext which unites our own group and excludes competing groups. The difference may be trivial. We regularly choose even more absurd differences, such as between closely related varieties of religion, to justify persecuting or killing our neighbours.

  Figure 5.2 Original distribution of skin colours in the Old World. With a few obvious exceptions such as Australia, the darkest-skinned groups still tend to live in sunny and tropical countries.

  Changing face

  Other, more solid differences, such as the shape of our face, are determined by the underlying skull bones. These do vary between different parts of East, Southeast, and South Asia, and imply a rather long period of separation between the populations of these regions. Throughout East Asia we see the Mongoloid type (see Plate 17) with an extra, so-called epicanthic fold protecting the upper eyelid, and broad cheeks and skull. This type is often further divided into Northern Mongoloid and Southern Mongoloid, with the latter showing a less marked eye-fold and including southern Chinese and darker-skinned Mongoloid types in Southeast Asia (see Figure 5.3).4

  A great variety of peoples is found in South Asia, particularly in India. The majority of Indians, although dark skinned, are more similar physically to Europeans and Middle Easterners than they are to East Asians. Europeans, with their long, narrow heads, round eyes, and pale skin are sometimes called Caucasian. The farther north in India and Pakistan we go, the closer is the physical resemblance to ‘Caucasoid’ Levantines and Middle Easterners. In southern India, darker-skinned, curly haired, round-eyed peoples predominate. In eastern India, Assam, and Nepal there are peoples with a more Mongoloid appearance.

  In Chapter 4 we looked at another category of Asian peoples who may represent remnants of the original beachcombing trek to Australia. Scattered around the coast of the Indian Ocean, in Pakistan and India, and in the Andaman Islands, the Philippines, and Malaysia, are several so-called aboriginal groups who are superficially more reminiscent of Africans and New Guineans, because of their very dark skin and frizzy hair. These minorities have been called respectively Negroid, Negritos, and Melanesians.

  Although they are just a tiny minority among the other Asian Old World peoples I have mentioned, such aboriginal groups have long been regarded by scholars as physically somewhat nearer to the first out-of-Africa people than are the other Asians. This generalization effectively suggests that it is the bulk of the rest of Asia that has changed. A parallel dental study of the same aboriginal populations that I sampled for genetic markers (Chapter 4) has produced physical confirmation of this view. Another piece of evidence in favour of these aboriginal groups being relicts of the beachcomber trail is that the earliest fossil skulls from Europe and from East and Southeast Asia from before the last glaciation are not typically Caucasoid or Mongoloid in shape. Instead, we see forms closer to the oldest African and Levantine skulls of 100,000 years ago.5

  Earlier people were bigger and more rugged

  How do we know what that first group of emigrants from Africa looked like in any case? The simple answer is that we do not. The reasonable and most parsimonious speculation, that they were dark-skinned and frizzy-haired, is based on the appearance of modern Africans,6 although it is unlikely that Africans of 80,000–100,000 years ago looked quite like those of today. There are, however, some clues.

  A few fossilized skulls of Anatomically Modern Humans have survived intact from around 100,000 years ago. One that is frequently referred to as characteristic of the period is from the failed first exodus to the Levant. It is named Skhul 5 after the cave where it was found. A number of other skulls were found in the same location – Skhul 5 was just one of the best preserved. A Skhul type was used to reconstruct the ‘face of Eve’ (see Plate 18) in our documentary film The Real Eve. Anatomically Modern Human skulls of this period show great variability, but they also share a few general characteristics that have changed in later populations, including modern Africans. Most obvious are the two closely related features of large size and ‘robusticity’. Robust features include large, craggy skulls, thick bones, and heavy brow-ridges when compared with all today’s populations. The opposite of robust, ‘gracile’, is used to describe individuals with a flat, high, vertical forehead, smoother brow-ridges, and thinner long bones and skull bones. Other ancestral features of the time before the southern exodus include a relative narrowness of the skull (narrow breadth side to side compared with length front to back) and a broad upper face.7

  Size and robusticity of the skeleton are closely linked (especially in the skull). This presents us with a problem when we try to use bones to reconstruct prehistory, because the most marked change since the time of the African exodus has been a progressive reduction in size and robusticity in all peoples of the world, including Africans. Although some of the long-term change is probably genetic, the most dramatic size reductions have occurred within the past 10,000 years and may, paradoxically, be nutritional rather than genetic.

  How did we get to be smaller?

  Early hunter-gatherers led a tough, roaming life and therefore had a low population density, but their diet was rich in protein and minerals and varied in vegetables. Conversely, although the cereal farmers of the past 8,000 years may have had a high per-hectare crop yield and large families as a result of early weaning, their diet was monotonous – high in carbohydrate, and low in protein, vitamins, and calcium. Early weaning with high-carbohydrate, low-protein foods resulted in growth-stunting persisting into adult life. Consequently, although populations expanded with the advent of farming, child and adult size decreased dramatically. This effect is particularly marked in peoples eating rice without much animal protein, as in the Far East.

  Today we can see the effect of reversing this form of cultural malnutrition. When East Asians migrate from a rice-eating culture to the USA and take on the low-bulk, high-calorie, protein-rich diet there, within two generations we see Asian children approaching the size of American children. American and European populations, with their improved diet, have also seen a steady increase in adult size since the Second World War.8

  So, if robusticity depends partly on size, and the average size of today’s regional populations depends on their present diet, then the value of these two important determinants of our appearance in tracing the differentiation of non-Africans over the past 70,000–80,000 years is reduced. Also, many of the changes in robusticity, size, and general appearance of modern humans since the out-of-Africa migration could actually be reversible with a good diet and a healthy lifestyle. The rugged ‘Neanderthal’ look of some large players of contact sports can now be explained.

  A couple of permanent changes can be observed over time, though: namely, in skulls and teeth. Reduction of skull size, to take that first, was caused by slightly different mechanisms in different regions.

  Changing skulls

  Although Australian aboriginals, and to a lesser extent some New Guineans, have undergone size reduction, they appear to have retained more of their skeletal robusticity than have nearly all other groups. The Australian skull reduction was both in length and breadth. Australian aboriginals are sometimes cited as the best examples of retention of the ancestral form, but, for several reasons, a better case could be made for New Guineans. A few details about the Australian aboriginals, past and present, remain unexplained – one is that the earliest fossil skulls from Australia were actually gracile, not robust. Another reason to regard the Australians as somewhat ‘changed’ f
rom the ancestral type, perhaps as a result of admixture, is that most Australians today have curly rather than frizzy hair.9

  Only one other modern group has retained a similar degree of robusticity to Australians and New Guineans, namely the Tierra del Fuegans of South America, and they are now practically extinct. In Japan another rather robust skull type is represented in the fossil record by the famous Minatogawa fossil skulls from Okinawa, a subtropical Japanese island, dated to the height of the last glaciation (see Plate 20). These skulls group by shape with the pre-Neolithic ancient Jomons of Japan, who are regarded as the ancestors of the modern aboriginal population of northern Japan, the Ainu. Among the ancestors of Europeans and Middle Easterners there was a limited and variable reduction in skull length and robusticity, leaving some degree of long skull shape (dolichocephaly) and also a variable retention of robusticity, which helps to explain my own beetle-brows.10

  It is in the peoples now called Mongoloid that the most marked changes occurred. The size reduction happened mainly by a marked shortening of the skull from back to front while retaining breadth and height. A further change that was characteristic of Mongoloid peoples was an exaggeration of facial flattening. This is most pronounced in Neolithic populations on the east coast of Lake Baikal in Siberia and around Mongolia (Figure 5.3). It is referred to as an exaggeration since facial flattening is not a new feature to the normal range of human variation. Facial flattening is also seen to a lesser extent in some early African skulls, in modern-day Khoisan hunter-gatherers, and in the revered founder-father of post-Apartheid South Africa. These changes resulted in the high, fine-featured, rather broad (brachycephalic) head shape now prevalent in East Asia, which is almost certainly genetically determined. East Asians are also among the most gracile of modern populations.11