Coons, The Origin Of Races

Makednos · Admin Posts: 9 Join date: 2008-01-21

The Origin of Races

On the Antiquity of Races

At the dawn of of history, which is another way of saying "beginning with Herodotus," literate people of the ancient world were well aware that mankind was divided into a number of clearly differentiated races. Even before that, racial differentiation can be traced back to at least 3,000 B.C., as evidenced in Egyptian records, particularly the artistic representations. We also have pictures of white people on the walls of western European caves which are as much as 20,000 years older.
How many kinds of people there were in the world was not really known until after the voyages of discovery that tore the veil from the Americas, the Pacific islands, and Australia. Even then the problem of classifying the races remained, and it has not been settled to this day.
For present purposes I am using a conservative and tentative classification of the living peoples of the world into five basically geographical groups: the Caucasoid, Mongoloid, Australoid, Congoid, and Capoid. The first includes Europeans and their overseas kinsmen, the Middle Eastern Whites from Morocco to West Pakistan, and most of the peoples of India, as well as the Ainu of Japan. The second includes most of the East Asiatics, Indonesians Polynesians, Micronesians, American Indians, and Eskimo. In the third category fall the Australian aborigines, Melanesians, Papuans, some of the tribal folk of India, and the various Negritos of South Asia and Oceania. The fourth comprises the Negroes and Pygmies of Africa. I have named it after a region (not a specific nation) which contains both kinds of people. The term Negroid has been deliberately omitted to avoid confusion. It has been applied both to Africans and to spiral-haired peoples of southern Asia and Oceania who are not genetically related to each other, as far as we know.¹ Negroid will be used in this book to denote a condition, not a geographical subspecies. The fifth group includes the Bushmen and Hottentots and other relict tribes, like the Sandawe of Tanganyika. It is called Capoid after the Cape of Good Hope. If this subspecies once occupied Morocco the cape can be thought of as Cape Spartel. Either way, the term is appropriate.
My aim in this book is to see how far back in prehistoric antiquity these human racial groups can be traced. Did they all branch off a common stem recently, that is, within a few tens of thousands of years, after mankind had evolved as a single unit to the evolutionary state of the most primitive living peoples? Or did their moment of separation lie lower down on the time scale, when long-extinct types like the so-called ape men of Java and China were still alive? If the second is true, much of the evolution of the different existing races may have taken place separately and in parallel fashion over a period of hundreds, rather than tens, of thousands of years. The first hypothesis is the one more commonly held, but it presents some impressive stumbling blocks!
If all races had a recent common origin, how does it happen that some peoples, like the Tasmanians and many of the Australian aborigines, were still living during the nineteenth century in a manner comparable to that of Europeans of over - oo,ooo years ago? Either the common ancestors of the Tasmanians cum Australians and of the Europeans parted company, in remote Pleistocene antiquity, or else the Australians and Tasmanians have done some rapid cultural backsliding, which archaeological evidence disproves.
If the ancestors of the living races of mankind were a single a few thousands of years ago and they all spoke a single language, how does it happen that the world contains thousands of languages, hundreds of which are unrelated to each other, and some of which even use such odd sounds as clicks? Some languages are tonal and others are not, and the difference between a tonal and a nontonal language is basic and profound. Eskimo and Aleut, which are closely related languages, have been separated for about two thousand years. It takes at least twenty thousand years for two sister languages to lose all semblance of relationship.' If, therefore, all languages are derived from a single mother tongue, the original separation must go back many times that figure. The only alternative is that more than one line of ancestral man discovered speech independently. Even so, the number of languages spoken by a single subspecies, the Mongoloid, is great enough to imply a vast antiquity.
All the evidence available from comparative ethnology, linguistics, and prehistoric archaeology indicates a long separation of the principal races of man. This is contrary to the current idea that Homo sapiens arose in Europe or western Asia about 35,000 B.C., fully formed as from the brow of Zeus, and spread over the world at that time, while the archaic species of men who had preceded him became conveniently extinct. Actually, the homines sapientes in question were morphologically the same as living Europeans. To derive an Australian aborigine or a Congo Pygmy from European ancestors of modern type would be biologically impossible.
The current idea is based on the study of comparative anatomy without reference to evolution, and a misunderstanding of paleontology. One anatomist, Morant,' found by means of a number of measurements taken on less than ten Neanderthal skulls that this ancient population differed in mean measurements from a number of modern populations more than the modern skulls differ from each other. The differences reflected mainly the fact that Neanderthal men had low, flattish cranial vaults and protruding faces; but these features could have come from a small number of genes concerned with adaptation to cold weather. Since 1927, when Morant's study was published, "progressive" and "transitional" high-headed Neanderthals have been unearthed in western Asia. These new discoveries suggest that the total extinction of that fossil race is unlikely. We now have fossil skulls from China, Africa, and Europe, found since Morant studied the Neanderthals, which closely resemble the modern races in features that seem to have evolved and been handed down locally. Such features in clude the extent to which the face is flat or beak-like, the shape of the nasal bones, and the size ratio of front teeth to molars. If we grant that races, like the species to which they belong, can evolve, our problem becomes simpler.
The misinterpretation of paleontology by nonpaleontologists came about naturally. Anyone who studies the family trees of various lines of animals over millions of years is bound to be impressed by the multitude of extinct species, and to notice that the living animal species are descended from very few ancestral ones. When this observation is applied to many forms of life over the span of geological time, it holds true; but for man it does not. Man is little more than a half million years old. Geologically speaking, we were born yesterday. The fossil men now extinct differed from each other in race, and were not members of separate species except in the sense that one species grew out of another.
As human beings are animals, they are subject to the same laws of evolutionary change that govern the rises and falls of other species and their transmutations into increasingly complex and efficient forms. Therefore we have two jobs to do: (i) to survey the rules of species formation and the differentiation of races, including the composition of populations, systems of mating, differential fertility, and geographical adaptation at different ecological levels, as they may apply to man; and (z) to go over with a fine-toothed comb all the original evidence about fossil specimens of man and his predecessors which can be found. This includes actual specimens, casts, and technical reports, some lying on the bottom shelves of library stacks, with pages still uncut, and undisturbed for decades. Because few textbook writers have bothered to consult these primary sources, few new ideas about the evolution of races have reached the public for a long time.

The Problems of Human Taxonomy: the Genus

Over two hundred years ago Linnaeus, the father of taxonomy,⁵orsystematics as he called it, initiated the practice of giving each species in nature an italicized double name, or binominal, one of which was Homo sapiens. The first word is the name of the genus and the second that of the species itself. In the species Homo sapiens he included all living peoples. At that time no fossil men bad been discovered, and the genus Homo had therefore but a single species.
Linnaeus used only one word to designate biological units smaller than the species: variety. At that time the concept had not yet arisen that the unit of inheritance and evolution is the population to which an individual belongs rather than the individual himself, and the exact meaning ofvariety was not clear. In recent years taxonomists, in reviewing the nomenclature of species, have found that many units given specific rank in the past were subspecies, or geographical races, of larger units, and that what had been called varieties were races of one magnitude or another, or even individual variants.
In order to obtain material for classification, zoologists were kept busy collecting skins and skulls of many kinds of animals, and paleontologists removing bones, teeth, claws, and shells of ancient animals from the ground. Rarely did the paleontologists have whole skeletons to work with; and even when they did, characteristics studied by zoologists, such as hair form and color, skin structure, and the number of mammary glands, could not be determined except in a very few cases, as when mammoths were found frozen in the ground.
Whereas zoologists could collect large numbers of contemporary specimens, paleontologists sometimes possessed only unique specimens, which had to be related to others from different times and different places. Often the time gap between apparently related specimens was so great that it was unlikely that they could have belonged to a single species. Being cautious men, most paleontologists considered it more conservative to give separate generic names to unique or rare fossils of different periods than to assume their identity, particularly when in living animals such as the sheep and goat, which belong to different genera, the only difference visible in the skeleton is the relative lengths of the segments of the forelimb. Paleontologists therefore formed the habit of giving new and unique specimens separate generic names, setting aside the finer classification of related species until more bones had been found. When, in the second half of the nineteenth century, paleontologists and archaeologists began turning up the bones of fossil men, some of them applied this practice to the much more limited field of anthropology, and we find such designations as Pithecanthropus erectus, Sinanthropus pekinensis, and more recently, Atlanthropus mauretanicus tagged to specimens some of which differ from one another no more than do individuals in the living species.

Homo sapiens

The final difficulty with this type of taxonomy is that it cannot be reconciled with our time scale. Simpson, Kurten, and others have shown that, within the geological periods with which we are concerned, a genus of mammals requires about eight million years to establish itself, and it usually makes no difference whether the animals are large or small, or fast or slow to mature.⁶
The oldest fossil-man remains that are definitely and indubitably Homo may be no more than 700,000 years old. If there really were, during the last 700,000 years, four genera of fossil men, including Homo, Pithecanthropus, Sinanthropus, and Atlanthropus, then these genera must have parted company early in the Pliocene, and we have neither manlike bones nor tools from this period.
Later on, after tools had appeared, we find that both Atlan-thropus in North Africa and Homo in Europe were making stylistically similar stone implements. Although a great many claims can be made for parallel evolution, it is inconceivable that men of two distinct genera could have made similar tools. The concept that the fossil men so far found, who lived during the last half million years, belonged to more than one genus is impossible both anatomically and in terms of behavior, as revealed by archaeology. This concept must be abandoned, and indeed many zoologists and anthropologists have already discarded it. Of the names proposed for our genus, Homo has two centuries of priority, and Homo is what we are, what our known ancestors were, and what our unknown ancestors could have been for as long as eight million years.

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The Species Concept

In the whole field of taxonomy no identification is as important as that of the species of an animal. Higher categories, such as the genus, family, order, and so on, are subject to argument and revision, and lower categories, the subspecies and local race, are also more difficult to establish. The species, however, is the pivot of the entire structure because it is the unit of evolutionary change.
In the early days of taxonomy, a collector would shoot a bird or animal, keep its skin and skull, compare it with others in existing collections to determine whether it was something new, and « it was, he would write up a detailed description, giving the bird or animal a new name. It thus became the type specimen, or holotype, of its species, and future collectors would compare their iscoveries with it. This practice was applied to the anthropologi-ai held. Blumenbach, whose classification of mankind in the miliar fivefold skin-color system is still used in some school geography books, selected a particularly handsome skull from a European collection as the type specimen of the white race, and as it had belonged in life to a native of the Caucasus Mountains, white people came to be called Caucasians, or Caucasoids, and still are. As late as 1912 Boule selected the skeleton of La Chapelle aux Saints as the type specimen of Neanderthal man, which he compared to the skeletons of one Frenchman and three anthropoid apes.
As early as Darwin, however, it was recognized that a species is not just the specimen that happened to be killed or unearthed first, and others later found to resemble it, but a population. Indeed, Darwin based his theory of natural selection on his observation that individuals of a species are variable, and that one need not be more typical than another. As time went on, it became clear that a species is a breeding unit or population, which has a gene pool of its own, and not just a collection of individuals, and that each population is a separate entity, living in two related states of dynamic equilibrium. The first regulates the balance between the individuals that compose the population. The second governs its relations with the other species in its environment.
Another early observation was that members of different species do not interbreed, at least in a state of nature. It was first thought that this was not for lack of trying but simply because each species was incapable of fertility with any other. However, early in the twentieth century the rising science of genetics made it clear that some animals of different species could produce felt tile offspring if they could be made to come together. Sterile hybrids like the mule were known from antiquity, and tiger-lion mixtures have been produced in zoos, but hvbridization, it was found, is not a common or important mechanism of evolutionary change in the higher animals, as it is in plants. Furthermore, as each species is in genetic equilibrium with its environment, the addition of new genes from an animal with a different kind of equilibrium could be expected to produce offspring less viable than either parent.
The important distinction is that members of potentially interfertile species do not ordinarily interbreed eitherbreeding periods fall at different seasons or because they simply do not attract each other: they do not recognize each other's mating symbols—visual, olfactory, auditory, or whatever.
In any case, whether or not unconfined animals of different populations interbreed when given the opportunity is the critical test of a zoological species. Paleontologists, of course, cannot use this test, which may be another reason why they prefer to deal in the more readily identified unit of the genus. In the case of living human populations, we can confirm Linnaeus's decision that all men belong to the same species, not only because all races are in-terfertile but also because some individuals among them interbreed, although others oppose mixture. In the case of early human populations unearthed by archaeologists, we cannot be sure whether interbreeding has or has not taken place; and at only one site, the Mt. Carmel caves of Palestine, is there any evidence—a high degree of individual variability combined with a mingling of tool forms—to suggest that the races were mixing, but even that is inconclusive. Therefore, the statements commonly made that Pithecanthropus, Sinanthropus, Neanderthal man, or a member of any other ancient population was unable to interbreed with his neighbors, if he had any, is speculative and cannot be demonstrated.
These statements are based on the old idea that if in some characteristic the ranges of variability of two populations fail to overlap, then these populations are different species. If this were true, then the Pygmies and Watusi of Ruanda-Urundi in Central Africa, who live near each other, would be different species on the basis of stature, and the black-skinned and white-skinned races of the world would also be different species.
This obsolete concept of single-character taxonomy has long since been abandoned. Zoologists now base their decisions on all the characteristics they can identify and measure, characteristics which together give the animal its essential nature, its (to borrow a psychological term) gestalt. The determination of species cannot be made by feeding figures into a computer. It is in a sense an art, practiced by men of experience who know, first of all, how species are formed.

The Spatial Requirements of Species and Their Geographical Differentiation

Zoologists recognize two kinds of species, monotypic and polytypic.' A monotypic species contains a single pattern of genetic composition, usually because it is a single population that occupies a single, environmentally unified lebensraum in which interbreeding is easy from one end of its territory to the other. Monotypic species are in the minority. A polytypic species, on the other hand, is broken up into a number of separate populations, each occupying its own territory. Usually these territories adjoin each other but are partially separated by environmental barriers. Gene flow across the barriers is infrequent enough to permit the development of separate genetic patterns but frequent enough to prevent the different populations from becoming individual species. When these barriers become absolute, local speciation can occur. Once a new species has arisen, it is likely to expand into a number of territories, where adaptation to new conditions will be rapid. This is undoubtedly what happened to our ancestors once they had acquired the erect posture and begun to use their hands for something beside locomotion and their mouths for something other than feeding and biting.
Regional populations of a polytypic species, once it has become established and has spread, are normally allopatric, a term which means simply "occupying different territories." If they were ntft allopatric, they would compete with each other for food, and one would drive out or absorb the other. Normally the one longest in situ has the advantage over newcomers because it has adapted itself to its new environment by favorable genetic changes, unless a geographical principle is involved, as in the case of isolated populations like those that arise on islands. Because they evolved with out competition, such populations are usually vulnerable when their territories are invaded by newcomers which evolved on large continental areas where competition is keen.
Related species, however, can be sympatric, which is zoologese for saying that they can occupy a single territory without interfering with each other, just as zebras, wildebeeste, and giraffes feed together on an African plain. Sympatric occupation is the rule for animals that belong to different genera, families, orders, and even higher categories of classification, which is why we have regional faunas. It is not very common among closely related species because they usually compete for food.
Whether or not related species are sympatric or allopatric depends to a large extent on their eating habits. If a species specializes in a narrow dietary range, it can coexist with another that specializes in a different range. The Australian koala lives essentially on the leaves of a few kinds of eucalyptus, the presence of which limits its range but allows it to coexist with other species of marsupials on the ground below; the giant panda of western China subsists largely on bamboo shoots whereas the smaller red panda eats a variety of foods.
Animal species that specialize in food are called > stenophagous, the Greek term for narrow-feeding. Those that eat many kinds of food are called euryphagous, or wide-feeders. Like any other specialty, stenophagy permits a rapid expansion in a narrow milieu, but it is not the road to evolutionary success. Euryphagy involves an animal in heavy competition, but if it survives, it has a better chance of expanding over areas with differing food supplies, and of undergoing further speciation.
In the case of man, he is euryphagous and always has been. Man can eat roots, succulent leaves, fruits, berries, eggs, and flesh. Except for grass, he can eat virtually everything that other animals eat, and this puts him in competition with many other species and with other populations of his own and related species.

The Subspecies

The next taxonomic division below that of species is the subspecies. A subspecies is a regional population of a polytypic species (a species with a number of separate populations) which meets two tests: (1) it occupies a distinct geographical territory; (2) it differs from other subspecies o f the same species in measurable characteristics to a considerable degree (to be specified shortly).
Subspecies must by definition be allopatric: if several subspecies were to inhabit a single region, they would breed together and the differences between them would be obliterated. Within its own geographical territory, which has an environmental character of its own, the subspecies has achieved, or is in the process of achieving, an adjustment to its local food supply, to the local climate, and to the behavior patterns of other animal species with which it shares its domain. After each subspecies has worked out a balance with all other elements in its local environment, it is not likely to change very much until its situation changes: natural selection will prune off unfavorable mutations that arise locally and keep the favored gene ratio constant.
Over the border, which may be a natural barrier such as a range of mountains or a patch of desert, or even a critical isotherm, may be found another subspecies of the same species, equally well established in a state of equilibrium with its environment. As the two environments differ in certain details, so do the genetic structures of its occupants. What is good for A is less advantageous for B, and vice versa. In each territory, natural selection keeps the gene structure of the local subspecies constant by also eliminating unfavorable genes that flow over the border. However, genes which are unfavorable in both environments may be eliminated in both populations, so that A and B may evolve together into a new polytypic species that retains its original set of subspecies. This is what we think happened when a number of human sub> species passed the threshold from Homo erectus to Homo sapiens.
Taxonomists have set up an arbitrary procedure to determine whether two or more populations within a species are morphologically different enough to qualify as subspecies. It is called the overlap test and is applied both to visible criteria, such as tooth size, and to invisible ones, such as blood groups. If in any well defined, presumably heritable morphological character, a representative sample of population A differs from a representative sample of population B to or beyond a critical degree, then we are dealing with subspecies. The critical degree is 75 per cent. If 75 per cent or more individuals of A are different from 100 per cent of B, then the two are probably subspecies.'
This method was devised for use on large samples of living animal populations and it can be applied to modern anthropometric series, but it is rarely if ever useful in the study of fossil man because we have few samples large enough for analysis by probability statistics. When applied to modern human populations, this test shows that Homo sapiens is at present a polymorphic species divided into a number of clearly differentiated subspecies, each centered in its own territory.
The concept of subspecies is essentially zoological and is used almost entirely to describe regional variations in animal species. However, paleontologists also use it occasionally, to describe steps in a single evolutionary line which they consider too small to merit the rank of separate species. Such units may be called successional subspecies, or waagenons-named for a mid-nineteenth century paleontologist, W. Waagen.' In order to keep confusion to a minimum I shall not use the word subspecies in this book to designate such successive units. When successive species must be split, I shall do it in terms of the evolutionary levels or grades through which they have passed.

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Mosaics, Clines, Local Races, and Racial Types

Below the taxonomic level of the subspecies, zoologists find a sometimes bewildering array of local racial variations of a minor nature, which exist because subspecies as well as species can be polytypic. This is as true of men as it is of mice, for man is the most mobile of mammals. He walks the land, flies the skies, and rides the oceans.
Part of the racial complexity of Homo sapiens disappears if we disregard for the moment the distribution of modern peoples like white and Negroid Americans, Latin Americans, South Africans, and white Australians and New Zealanders, whose ancestors reached their homes by ocean-going ships in recent times. Before then each of the five subspecies recognized in this book was firmly and uniquely installed in its geographical center. Between the nuclei of these five centers lie intermediate regions of two kinds.
One of them is the mosaic, which contains relict populations living as enclaves in refuge areas. For example, in India at least two forms of Australoids, classified as "tribal peoples," dwell in the hills, surrounded by Caucasoids whose home is the plains. Such a mosaic pattern is the product of earlier, but not geologically ancient, migrations that have not had time to fuse. As will be shown in the next chapter, it is typical of the tropics of the Old World. The other is a region of racial transition, a frontier-in-depth within which a subspecies grades into another through intermediate forms. It may be called a clinal zone because in it the population of the species intergrades in one or more measurable characters. In each heritable feature, the gradient is called a cline.1 For example, the living Europeans grade from a high frequency of blue eyes in the northwest, particularly in Ireland and Scandinavia, to a high frequency of brown eyes in the southeastern part of the continent. This eye-color gradient is a cline.
Whole complexes of related clines are found in clinal zones. For example, in central Asia north of the Himalayas Caucasoids merge into Mongoloids through the persons of several Turkic-speaking peoples like the Kirghiz, Uzbeks, and Turkomans. This clinal zone is a broad one. On the southern face of the Himalayan wall a similar but narrow clinal zone stretches through a steep intermediate altitude zone, in northern India, Nepal, Sikkim, Bhutan, and NEFA (Northeast Frontier Agency). As can be seen by these examples, the sharper the environmental barrier the narrower the clinal zone between subspecies.
Not only in relict enclaves and clinal zones, but also within the nuclear territories of subspecies, regional populations of minor rank may be found which differ from each other in perceptible ways short of the requirements of subspecies. These are known as local races. As they rise and disappear rapidly, they receive little attention from zoologists and usually none from paleontologists. In man they are considered important by people without a biological background, usually because such groups may be identified to a certain extent with social, political, or religious units.
How many local races could be identified and counted among living men is difficult to say, and different anthropologists might each find a different number. Such details are of no importance in this book, but it is important for us to know that local races exist and are formed by the same biological mechanisms that have fostered larger taxonomic units in the past.
Races like the Nordic, Alpine, Mediterranean, East Baltic, and Dinaric, which loom large in the Europe-centered literature of anthropology, are neither subspecies nor, in a strict sense, local races, although some local races may be defined in these terms. These words have also been used in the sense of types, which can be picked out of local populations. One may find a Spaniard who is typically Nordic in the midst of a population of Mediterraneans, including his own brothers. In a sense the situation is genetically comparable to finding a man of blood group B whose father's group was A. Types selected in this fashion are interesting to observe, and we notice them every day. Whether or not they reflect the origins of a population in one way or another, we must remember that from the taxonomic point of view such types are not races but simply the visible expressions of the genetic variability of the intermarrying groups to which they belong.
However, if we return to the first test of subspecies, geographical integrity, we are at first sight on shakier ground. Whites, Negroes, and American Indians occupy the United States sympatrically. Hindus, Fijians, and Europeans similarly occupy the Fiji Islands, and many other examples might be cited. As we study each instance, we find that this situation is a recent one, as time is measured biologically, and it is always associated with the expansion of peoples who have left the food-gathering stage of subsistence far behind.
Let us omit, for the moment, the agricultural peoples of the world and the colonists, and consider only the peoples who still are, or until recently were, food gatherers. These hunters and collectors are drawn from all five geographical races listed on page 3. Each race is confined to a single territory without overlap except in two regions: India, and southeast Asia plus Indonesia. Owing to a lack of skeletal material, we do not know when the ancestors of the various food gatherers moved into India, nor indeed which race was earliest there. In southeast Asia and Indonesia we know, as will be explained in Chapter 10, that Mongoloids began replacing Australoids about 10,000 years ago, after the invention of the bow and the domestication of the dog had made some hunters more efficient than others.
This southward movement was a trickle compared to what happened in many other places 4,000 years later. By or after 6,000 s.c. a number of local populations began to advance from the ecological niche of hunters and gatherers to that of food producers, and territorial expansions followed. These movements started no more than four hundred generations ago, counting twenty-five years to a generation. The colonial movements that brought Europeans to America, South Africa, Australia, and New Zealand took place less than twenty-five generations ago; only about twelve generations separate most descendants of passengers on the Mayflower from their celebrated forebears.
These various movements have greatly restricted the territories of aboriginal food gatherers, but gatherers are still present in reduced numbers. Many more have been absorbed into the new food-producing populations or have borrowed the techniques of food production from newcomers to their territories. Since the beginning of agriculture no new subspecies have arisen; the principal changes that have taken place have been vast increases in the numbers of some populations and decreases to the threshold of ex tinction in others. All this points to one conclusion: the living subspecies of man are ancient. The origins of races of subspecific rank go back into geological antiquity, and at least one of them is as old, by definition, as our species.

The Differentiation of Species

Species formation is believed to be the product of four principal factors: mutation, recombination, selection, and isolation.' A mutation is a heritable, spontaneous, and within certain limits random change in the chemical composition of a molecular segment of a chromosome known as a gene cr gene locus.' These changes take place normally in all organisms at individual frequency rates that can be predicted. As most mutations produce unfavorable effects, relatively few are passed on or participate in species formation. The same mutation, favorable or otherwise, can appear time after time, at its own rate, in individuals of different races. Yet mutation is the primary element in evolution. The other three are secondary.
Recombination, known as Mendel's second law, is the process by which rows of gene-molecules strung together on chromosomes break up and form new associations.' At meiosis, that critical moment in fertilization when a single array of paternal chromosomes lines up with and joins a single set of maternal chromosomes, the pairs do not always merge with each other in a regular fashion. Some chromosomes cross over each other at various loci and trade strings of genes. Others break up and the fragments attach themselves to other chromosomes or get lost. These new arrangements can also cause changes in the resultant organism.
Selection is the well-known pruning process by which the environment determines which novelty produced by mutation or recombination shall gradually spread through the group because of its superiority to the old trait it replaces, and which novelty shall be eliminated because it is unfavorable. As most mutations are unfavorable, when a species is not perceptibly changing, selection serves almost entirely to preserve the status quo. However, the process of replacement is characteristically slow. Old genes have a habit of hanging on as minorities, and if the environment changes back once more, they may re-emerge as majorities, in new combinations.
Isolation, the fourth factor, is necessary for the rise of new species because, unless a breeding population is self-contained, natural selection may be unable to eliminate old, unfavorable genes from its pool. A constant gene flow from neighboring populations may renew the old genes as fast as they are being lost. In a monotypic species such gene flow is impossible by definition. But in a polytypic species only those genes can be eliminated which are unfavorable to all its component units. When this happens, the species evolves as a whole, whereas its component populations may retain their local differences.

Balanced Polymorphism

Sometimes it is disadvantageous for a population to eliminate its old genes completely. An old gene may possess the ability to meet an old crisis, if that crisis should return. Furthermore, the old gene and the new one with which it shares, as an alternate, its position on a chromosome may do things together that neither could do alone.
In genetic shorthand, AB may be better under some conditions than either AA or BB. The best-known example of this effect in man is probably the so-called sickling trait common among West African Negroes. This is expressed by the letters S and s. S means that you have the trait, s that you don't. The S gene curls the red corpuscles in the blood, impeding oxygen flow; the s gene has no known effect. The S gene alone resists malignant malaria, which kills many children. But an SS child may die of oxygen starvation, and an ss child of malaria, whereas an Ss child is likely to survive >diseases. The population profits by the retention of both genes, each of which has a disadvantage in that particular environment.
The example just cited may explain the presence of genetic variability in many populations even though we don't yet understand why it is there in each case. It may also in part explain the re-emergence of "types."

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On the Timing of the Individual Growth Cycle

In addition to mutation, recombination, selection, and isolation, biologists have discovered a fifth evolutionary process which is tertiary because it depends on combinations of the other four, only one of which, mutation, is primary. This is a heritable change in the time of appearance of different characters in the growth cycle of the individual.
Each organism passes through three principal stages of development. It starts as an embryo, a fertilized egg in the process of cell division which has not yet reached the point where an em-bryologist can tell its species. In man this condition lasts about nine weeks. Then in mammals it becomes a fetus, in birds a chick, and in insects a larva.⁵ After it has been born, pecked its way out of its shell, or left its cocoon, it starts on the road to adult life in different stages of preparation, depending on the class of animal it belongs to.
Both in fetal and postnatal life, the individual must be adjusted to its environment, or it will perish. Certain traits that are necessary to the fetus and useless to an adult appear in fetal life and then disappear. Other traits appear as they are needed. Incidentally, it is not true that every individual recapitulates the forms of all its ancestors from the beginning of life on earth. We do, however, recapitulate many of the fetal traits of our ancestors, but not all of them, and not all in the original order. Nevertheless, the etus possesses a vast store of transient genetic characteristics that could be used in adult life under different circumstances.
One of the features that all animals inherit is a built-in timing schedule which regulates the order of appearance and the duration of growth of different bodily systems. This schedule can be upset through standard genetic mechanisms, such as mutation and recombination. The survival of fetal traits into adult life occasioned by such a change is called neoteny.
The classic example of neoteny is the life cycle of an amphibian of the salamander group, the axolotl. This animal arrives at sexual maturity during its tadpole stage and never leaves the water to become an air breather like other salamanders, frogs, and toads, but reproduces and dies in its original medium. Other examples are found among certain birds that have lost the power of flight. They retain throughout life the down that covers the chick before it breaks out of its shell. Ostriches, emus, cassowaries, and penguins have all acquired this neotenous change independently.
In man's ancestors neoteny may have been at play before the appearance of Homo erectus. The position of the head on the neck at right angles to the axis of the vertebral column is neotenous; it is found in the fetuses of all the primates and indeed in those of other mammals. In the fetuses of primates in general the thumb is relatively long in proportion to the length of the other fingers. Among many monkeys and all apes the adult animals have short thumbs, which in man remain neotenously long throughout life.
In insects, which are born fully grown and completely adult, all changes in timing have to be neotenous. In mammals, which are small when born and dependent on their mothers for food and protection, the infantile form differs markedly from the adult in many ways. A baby mammal has to grow mightily and in most species rapidly, and in the higher species it has much to learn. As growth is largely controlled by the endocrines, any shift in endocrine balance can cause radical changes in the form and appearance of the adult animal.
In man some races appear infantile in certain respects throughout life, whereas the children of other races look like miniature adults. In some races the color of the hair never changes during an individual's lifetime, except among persons who reach advanced senility. In others the hair may start out blond, become brown at puberty, and turn white by the age of thirty.
The classbook issued to the members of the Harvard class of 1925 at our twenty-fifth anniversary contains two portraits of each man who was still alive in 1950 and who could be reached. One portrait was taken at graduation, the other twenty-five years later. In some individuals almost no change can be detected; others had changed so much that they were unrecognizable. Yet nearly all these men were of the same racial origin. Age changes, then, vary within populations as well as between them. Not one of my classmates, however, looked like a Pygmy or a Bushman.
Races that retain a number of infantile features throughout life are called pedomorphic; those in which mature features appear early are called gerontomorphic, after the Greek words pais, a child, and geron, an old man. Pedomorphism and gerontomorph-ism are most conspicuous in external, visible anatomy, but they can also affect the nervous system, the vocal cords, other covert systems and structures, and behavior. Most fossil men that we know were gerontomorphic, as witness their heavy brow ridges and long faces. Homo sapiens as a whole seems to be relatively pedomorphic, although variable in this respect both racially and individually.

On Size and Form: Allometry

We must be careful, in seeking for relationships between different races, not to confuse pedomorphy and gerontomorphy with normal variations that take place when animals of the same or related species grow smaller or larger. A mouse has a larger brain, in proportion to its body size, than a rat does. A Great Dane's eyeballs are proportionately smaller, although absolutely larger, than those of a terrier.
Animals that are otherwise genetically similar vary in proportions according to size, the small ones being more compact, the larger ones more attenuated. The principle governing these differences is called allometry. Zoologists not only recognize this rule express it in formulas. For example, in the horse family face length equals .3 times skull length, to the 1.2 power.⁶ A big horse has a longer face, both absolutely and relatively, in proportion to his skull length, than a small horse does. By the same token, an average African Pygmy has relatively shorter legs and a relatively larger head than does an average African Negro.

On Sexual Dimorphism

Another factor to be considered in comparing races and species is the degree of differentiation between adult males and females in a population. This is called sexual dimorphism. It varies greatly both in mammals and birds. Male and female cardinals have feathers of different colors; yet it is difficult for a nonorni-thologist to tell a male from a female robin. Among the primates, a male gorilla may be twice as large as any member of his harem, whereas the only visible difference in gibbons in the wild is the protrusion, through the fur, of nipples in the female that has borne offspring.
Sexual dimorphism serves two principal purposes. First, it may be part of the selective process in mating, as when male birds strut their plumage in the nuptial ceremony, and as when stags lock their horns in mortal combat in competition for a doe. Second, among some animals that inhabit distinct territories, as for example lions, or baboons living in a forest, the exaggerated size and fighting equipment of the males permit them to serve the function of a border patrol in human communities. The male keeps rivals off his feeding ground and away from his wife or wives. Neither the male lion nor the male baboon is any better at obtaining food than his womenfolk; in fact, among lions the female excels at hunting. These animals expend their biological capital for territorial defense, just as we spend the bulk of our tax money for atomic submarines and missiles.
In fossil man there is evidence of sexual dimorphism, but it is clouded by the paucity of material available for study. In living races a great variability can be seen. Australian aborigines and western Europeans are highly variable; Mongoloids little. As Tibetans dress and wear their hair alike, it is sometimes difficult to tell whether any one person is a man or a woman. This does not mean that sexual dimorphism is the same as pedomorphy, for some populations with little sexual dimorphism are in certain ways gerontomorphic. No one could call a Plains Indian infantile, and his women can be huge and craggy. It is difficult, then, to decide whether certain racial traits, like the absence of a beard in many Mongoloid males, are the result of pedomorphy, of a lack of sexual dimorphism, or of some other aspect of the endocrine story yet to be discovered.
In any case, the presence or absence of marked sexual dimorphism is an inherited racial trait that distinguishes some living populations from others. This trait may date back to remote antiquity since it was not involved in the complex of evolutionary changes that led from Homo erectus to Homo sapiens. Of this we may be fairly confident because the two races that have achieved the greatest cultural advancement, the Caucasoid and the Mongoloid, stand at opposite poles in this respect. At the other end of the cultural scale, so do the Australian aborigines, who show marked sexual dimorphism, and the African Bushmen, who show little of it.

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How Species Have Evolved

Like all men, all species must eventually die. Just as some men perish with neither issue nor close kin and others achieve partial immortality through the transmission of some of their genes to their offspring, or more remotely, by the survival and reproduction of their brothers and sisters—so some species become utterly extinct whereas others live on, in a shadowy way, through one or both of two evolutionary mechanisms, succession and branching. Succession is also called phyletic evolution or anagenesis; the technical word for branching is kladogenesis. Evolution through succession occurs when a genetically iso-ted population acquires a new and favorable hereditary trait ^at is controlled by a single gene or by a complex of genes operating in concert. Then the new trait gradually replaces the old one through natural selection.
Evolution through branching occurs when two or more geographically separate populations of a single, polytypic species become genetically isolated from one another and then evolve into species of their own.
Succession tends to favor a process known as general adaptation whereas branching works rather through special adaptation, but the two are not mutually exclusive.
General adaptation involves the acquisition of a new trait or trait complex that is useful in more than one environment and under various different circumstances. Warm-bloodedness in birds and mammals is one example. Another is an increasing intelligence, which many forms of animal life have developed throughout geological history. A more limited example is the power of speech, which is useful to all men.
Special adaptation involves the acquisition of a new trait or trait complex that is useful in a single environment under special circumstances. It is the process which enables an animal to resist heat, cold, or bright light, to see well in dim light, to run faster or to swim better than its fellows, or to live without water in deserts, and which gives it many other such specializations. Special adaptation led the ancestors of the whales from the land back into the sea, and general adaptation gave them the intelligence needed to communicate with one another, by a system similar to sonar, and to survive, as mammalian populations, in their aqueous medium.
General adaptation tends to lead a species into evolution by succession because most species are polytypic, and a polytypic,,-species includes several populations living in different environments. Each of these populations becomes adapted to its special environment to a certain degree, but it cannot speciate by branching as long as it remains in genetic contact with its sister populations, since new traits involved in local specialization cannot completely replace old ones while genes continue to flow back and forth. If, however, in one or more populations a new trait appears which is equally favorable to all the populations and in all the environments occupied by the species, then the existing gene flow will help the new trait replace its predecessor in all the component populations, including that or those in which it started. By this process the old species evolves as a unit into a new species. At the same time speciation need not prevent the component populations from carrying their old, partial specializations, such as to heat and cold, from one species into another.
If however, a single population of a polytypic species becomes physically isolated from its fellows, so that gene flow is completely interrupted, then that population can evolve by branching. Now special traits that have no general value can completely replace the old ones that used to flow in over the border. If such a population happens to be confined to a small space, such as an island, ^and has no natural enemies, it can become a monotypic species as specialized as the dodo, the classic example of this process.

Fig. 1 How One Polytypic Species Can Evolve Into Another. Above: Five subspecies, in peripheral contact with each other, are illustrated by five circles, numbered l through 5. A mutation favorable to all five arises in No. 3. It spreads to Nos. 2 and 4, and is carried by further peripheral gene flow to Nos. 1 and 5. When all five subspecies have it, the species has begun to evolve into a new one by anagenesis—evolution through succession. Below: In this example the favorable mutation arises independently in Nos. 3 and 5, and, except for the direction of gene flow between Nos. 4 and 5, speciation takes place as in the first example.
Although the component populations of a polytypic species evolve as a unit, they cannot do so simultaneously since it takes time for a mutation to spread from one population to another. If we measure time on the broad scale of tens of millions of years used by paleontologists, these changes may appear simultaneous, but if we measure it on the geologically microscopic scale of the last 700,000 years, which is the age of man, we will see that related populations, which in our case are subspecies, passed from species A, which is Homo erectus, to species B, Homo sapiens, at different times, and the time at which each one crossed the line depended on who got the new trait first, who lived next to whom, and the rates of gene flow between neighboring populations.
Whether a new species is polytypic or monotypic, whenever it arises the evolutionary process is essentially the same. The new, critical trait responsible for speciation first appears in a few individuals, and its presence makes little difference to the population in which it arises. It may even appear and disappear several times before it takes hold. But after it has begun to spread, a point is reached when those who have it begin to outnumber those who don't. This point is marked by a rapid growth in population. The particular population has gained an advantage over competing species in its own lehensraum, and in the process it has become a new species of its own.
It need not, however, have completely lost the gene or genes for the old trait that is on the way out. After the new species has established itself, become stable in numbers, and reached a new equilibrium with the other species of plants and animals in its environment, the old trait may completely disappear. At that point a second and final threshold of speciation has been crossed. One may say that a new species has come into existence when it has acquired a new and more favorable ecological position, and that/ it has reached maturity when the traits responsible for these changes have completely replaced their predecessors. By the time the second threshold has been crossed, as likely as not a new species-forming mutation shall have begun to appear, and the cycle has started over again.
It is easy to understand, then, why some populations within any polytypic species have come closer, at any given time, to the second threshold of speciation than other populations. In man some groups of people alive today have preserved archaic traits, diagnostic of Homo erectus, in a higher percentage of individuals than other populations. For example, more natives of New Caledonia have big teeth and heavy browridges than a corresponding percentage of Japanese.
This and similar disparities can be explained in two ways.
(1) The more archaic population acquired the new trait complex that led to speciation later than the more modern population did.
(2) After crossing the first threshold of speciation, the more archaic population has been discarding its old traits at a slower rate than the more modern population:
Both explanations can be true at the same time. There is no necessary correlation between the time at which a threshold was crossed and the rate of change that follows the crossing. In either case, the critical mutation may have been original to the population concerned, or it may have been acquired by gene flow from a neighboring population. The older the trait the more likely that it was original; the younger the trait the more likely that it was derived from outside.
In any event, once a species has come into being, the old species from which it evolved is extinct. There are several kinds of extinction: utter extinction without issue, which is commonest among monotypic species; extinction through absorption, by which a subspecies ceases to exist as a separate entity when its remaining members are taken into the body of another; and extinction through successive evolution, which is the process we have just described.⁷
In the case of man, only the second and the third kinds of extinction can be traced. The Tasmanian aborigines who died out in the nineteenth century have living survivors among the racially mixed inhabitants of the islands between Tasmania and Australia, and the Fuegian Indians of South America are disappearing into the mixed population of that continent. But neither Tasmanians nor Fuegians were whole subspecies. The Australoid and Mongoloid divisions of man to which they belong survive in large numbers elsewhere. There are also, in a sense, degrees of extinc-ion, for it takes a long time, on our human time scale, for one species to replace another completely, and in that sense some human races are more nearly extinct than others.

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On the Life Spans of Mammalian Species⁸

Although the antiquity of Homo sapiens will be the subject of detailed study in later chapters, we may here profit from a consideration of the life spans of our fellow mammals during the Pleistocene and Recent (or post-Pleistocene) periods, the only periods in which man or any of his close kin are known to have lived. By international agreement the beginning of the Pleistocene has been established at the point when modern genera of elephants, horses, oxen, deer, and some other large mammals were first seen on the continents of the Old World, excluding Australia. The movement that brought them in, mostly from the New World, took place about one million years ago.
Before that stretched the vast temporal expanse of the Tertiary —Paleocene, Eocene, Oligocene, Miocene, and Pliocene—comprising some 77 million years, the Pliocene alone taking up some 12 million. During this long span individual species were born, flowered, and died at what seems to us a leisurely pace. The life expectancy of a mammalian species was then anywhere from one to eight million years.
During the first 300,000 or 400,000 years of the Pleistocene this pace continued, but it was suddenly quickened in various parts of the Old World, particularly its northern portions, by geological events. The planet's crust wrinkled more rapidly than before, raising the toothed edges of mountain ranges and creating great contrasts of climate, both regional and seasonal. First mountain glaciers, then continental icecaps crawled forth and melted away, blowing, like pairs of bellows, alternately cold and warm. In large tropical land masses, as in much of Africa, the bellows blew wet and dry.
^s This section is based on many sources, including books by G. G. Simpson. However, specific facts and figures come principally from two works of Bjorn Kurten: "Rates of Evolution in Fossil Mammals," CSHS, Vol. 24 (1959), pp-205-15, and "Chronology and Faunal Evolution of the Earlier European Glacia-tions," SSF-CB, Vol. 31, No. 5 (i960) pp. 1-62.
In response to these changes, new species evolved rapidly. Many became extinct, but others survived. The life expectancy of a species now dropped to a mere 360,000 years. At a point in time pegged at 300,000 years ago, all or nearly all the living mammals of the European and neighboring fauna, which were fox-sized or larger, had come into existence. The species which have since appeared are bats, insectivores, and rodents, all small animals. During the last 75,000 years, no new mammalian species seem to have evolved at all. Three hundred thousand years ago the evolution of new species of medium-sized and large mammals came to a halt. The heyday of speciation was over.
The oldest known Homo erectus is believed to be 700,000 years old. He appeared during the period of frenzied mammalian speciation mentioned above, and seems to have lasted until less than 100,000 years ago in remote parts of the Old World. His known life span as a species, about 600,000 years, was within the normal range for a mammal of his size and vintage. As I shall show in Chapter 11, Homo sapiens appeared about 250,000 years ago in an archaic form. Completely modern forms of our species appeared at least 35,000 years ago. Unless our species is a curious exception to the rules by which the game of speciation is played, Homo sapiens should go back to 360,000 or 300,000 years ago. This figure would place Homo sapiens in the fauna to which he belonged, and would give Homo erectus, who appeared exactly when he should have, ample time for speciation by succession.
So much for the actuarial statistics of Pleistocene and Recent species. With subspecies the reckoning is more difficult because subspecies are not easy to sort out when found among fossils. We nave no satisfactory information except that subspecies of the ibex nave been traced back at least 230,000 years.⁹ In the case of man, the subspecies of Homo sapiens are probably of different ages, depending on the times at which regional populations of Homo erectus, in one way or another, crossed the sapiens threshold. But all of them did this before the end of the Pleistocene.
in modern times we have seen whole tribes and peoples disappear after their lands had been invaded by Europeans and other culturally dominant strangers. The native Tasmanians are gone, and so are the Indians of Lower California. The Andamanese of the main islands, the Fuegians, and many others are on their way out. These sad cases of ethnic oblivion give us a feeling that human history is a long record of utter extinctions, but this is not true.
All species are destined to become extinct, but, except as they are parts of species, subspecies need not follow this rule. By definition, species do not ordinarily interbreed, but subspecies do. The Tasmanians were absorbed by the Caucasoids who replaced them on their island. A mixed Tasmanian-European population survives today. If the Indians of Lower California left no mixed descendants—which is unlikely—other Indians very much like them are still alive. When subspecies disappear, they usually, if not always, do so by absorption. Their genes linger on polymor-phously with those of their conquerors, to re-emerge, now and then, when needed. The principle is that when a population has been invaded by members of another race the genes that give it its special adaptation to its local environment retain their selective advantage and eventually come to characterize the mixed population through the process of natural selection. For example, central Europe was invaded from the East many times from the Neolithic through the Iron Age, but central Europeans still look more like the hunters of the Mesolithic than like the invaders.¹ Without the concepts of absorption and re-emergence it would be difficult for us to explain the physical diversity and geographical distribution of the living human races.
Part of this diversity may be relatively new. I refer here especially to the reduction in body size that has affected many species of mammals since the end of the Pleistocene, some 10,000 years ago. As will be explained in Chapter 3, extreme cases of size reduction in plants and animals take the form of dwarfing, which means that an irreversible genetic change has taken place. Our species includes a dozen or more populations of dwarfs, living in Africa, southern Asia, and Indonesia. As far as we know, all human dwarf populations are geologically recent.

Genetic Principles and the Origins of Races

In recent decades the pursuit of anthropometry has declined, except for applied anthropology. Instead of measuring the bodies of the last remnants of aboriginal populations, anthro-pometrists measure military personnel and civilians in order to design railroad and airplane seats and space suits. Doctors of Philosophy have become tailors to the new age of science. On the other hand, the pursuit of human genetics has become popular, particularly the study of the frequency in populations of blood-group genes, taste thresholds, mid-digital hair, and hairy ears.
In tracking down the lines of descent of fossil men, none of these characteristics is useful. Thieme and others have shown that it is impossible, using present techniques, to determine the blood type of samples of bone, for they all tend to absorb a group A substance from the ground.² Dead men cannot taste noxious chemicals, and the hair on their fingers and ears has long since decayed. What could be done, however, is to work out the relationships between fossil specimens and populations in terms of details of tooth structure, for teeth do not change with age except to be worn down. Molar cusp-numbers, the presence or absence of a kind of curvature of the incisors known as shoveling, and many other features that are preserved in the fossil record are just as useful for genetic studies as blood groups are among the living, and paleontologists have long relied on teeth. Although much work has been done on human teeth- no one has yet produced a work of synthesis covering all fossil specimens by means of which they could be compared with living populations.
Limited as the direct application of genetics is in the study of fossil man, the theoretical aspects of that science have helped us greatly. They have taught us that the unit of inheritance is neither the individual nor the arbitrarily chosen type, often identified with an individual, like Nordic, Dinaric, Neanderthal, and Cro-Magnon, but the population, and that each population has its pool
of genes with several possible alternates, known as alleles, from many if not all loci. We also know that because individual mutations recur at characteristic rates, resemblances between populations of the same species do not necessarily imply recent common descent. All curly-haired populations do not have to be descended from a common curly-haired ancestor. Pockets of blondism found among nonwhites need not be explained by Viking invasions, nor all Pygmies be considered as having derived from a single tribe.
An acquaintance with the principles of genetics may also help us solve the central problem of this book—that is, to discover how long ago the ancestors of the human subspecies parted company. We have learned, for example, that evolution proceeds trait by trait, one mutation, recombination, or whatever, at a time. If parallel mutations have been occuring in two populations, we cannot expect a large number of identical changes to have taken place at once in each group. Changes in the skeletons of fossil men from period to period in each major area seem to have involved very few factors, not many of them visible below the neck.
Brains have grown larger and brow ridges smaller. Jaws have sprouted chins and teeth have grown smaller in various degrees. Whole sets of these changes can be linked together as common products of one or more shifts in endocrine balance, shifts advantageous in an increasingly group-oriented society in which self-control comes to be more conducive to survival than a hot temper. Other changes may simply reflect a reduction in chewing, especially after the invention of cooking. If in each of several relateu populations, living in its own territory, changes like these took place not all at once but in sequence, it is possible that each single, parallel mutation prepared the ground for the selective advantage of the one that followed it.
On the other hand, if these sequences of genetic change were initiated in some of the populations by sexual contacts with people from other regions (peripheral gene flow), it would be difficult for us to detect this outside influence from an examination of the skeletons of the resulting mixed population because other genes transferred by the same contact might be disadvantageous in that particular area and would have been eliminated by natural selection. Although we cannot hope to settle the question of parallel evolution versus peripheral gene flow in the evolution of each race bv examining fossil bones and nothing else, such a study may show us how far back in time the various geographical races go. Some of our subspecies are characterized by traits that seem to have had little relation to either climate or culture during the known history of man, and whatever selective advantages or disadvantages they may have must have been acquired long ago. Among these traits are the architecture of the teeth, the shape of the nasal bones, and the degree of flatness of the face. If various combinations of these traits can be seen to have persisted in their special geographical regions despite other changes of a more clearly phyletic evolutionary nature, then the antiquity of individual races may be established. In any case, no form of evidence is unwelcome and only by a close study of detail can we hope to solve this and related problems.

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