Competition among members of the same species is not unique to humans. Among all animal species as well, the closest competitors are inevitably members of the same species, because they share the closest ecological similarity. What varies greatly among species is the form that competitive strife takes. In the most inconspicuous form, rival animals compete merely by consuming food potentially available to each other and exhibit no overt aggression. Mild escalation involves ritualized displays, or chasing. As a last resort, now documented in many species, rival animals kill each other.
The competing units also vary greatly among animal species. In most songbirds, such as American or European robins, individual males or else male/female pairs face off. Among lions and common chimpanzees, small groups of males who may be brothers fight, sometimes to the death. Packs of wolves or hyenas do battle, while ant colonies engage in large-scale wars with other colonies. Although for some species these contests may end in deaths, there is no animal species whose survival as a species is even remotely threatened by such deaths. Humans compete with each other for territory as do members of most animal species. Because we live in groups, much of our competition has taken the form of wars between adjacent groups, on the model of the wars between ant colonies rather than the small-scale contests between robins. As with adjacent groups of wolves and common chimps, relations of adjacent human tribes were traditionally marked by xenophobic hostility, intermittently relaxed to permit exchanges of mates (and, in our species, of goods as well). Xenophobia comes especially naturally to our species, because so much of our behaviour is culturally rather than genetically specified, and because cultural differences among human populations are so marked. Those features make it easy for us, unlike wolves and chimps, to recognize members of other groups at a glance by their clothes or hair style. What makes human xenophobia much more lethal than chimp xenophobia is of course our recent development of weapons for mass killing at a distance. While Jane Goodall described males of one group of common chimps gradually killing off individuals of the neighbouring group and usurping their territory, those chimps had no means to kill chimps of a more remote group, nor to exterminate all chimps (including themselves). Thus, xenophobic murder has innumerable animal precursors, but only we have developed it to the point of threatening to bring about our fall as a species. Threatening our own existence has now joined art and language as a human hallmark. Hence Chapter Sixteen will survey the history of human genocide, to make clear the ugly tradition from which Dachau's ovens and modern nuclear warfare spring.
THIRTEEN
THE LAST FIRST CONTACTS
For most of human history, human populations lived in a state of xenophobic isolation from each other, tempered by the need for trade and for exchanging spouses, but reinforced by differences in language and culture. In the modem world, 'first contacts' of isolated populations by outsiders have been accelerating, to the point where the last first contact is expected within the present decade. The end of our mutual isolation is bringing a tragic loss in our cultural diversity. Yet it also brings the hope that we may not continue destroying each other with increasingly powerful weapons.
On 4 August 1938, an exploratory biological expedition from the American Museum of Natural History made a discovery that hastened towards its end a long phase of human history. That was the date on which the advance patrol of the Third Archbold Expedition (named after its leader, Richard Archbold) became the first outsiders to enter the Grand Valley of the Balim River, in the supposedly uninhabited interior of western New Guinea. To everyone's astonishment, the Grand Valley proved to be densely populated—by 50,000 Papuans, living in the Stone Age, previously unknown to the rest of humanity and themselves unaware of others' existence. In search of undiscovered birds and mammals, Archbold had found an undiscovered human society. To appreciate the significance of Archbold's finding, we need to understand the phenomenon of'first contact'. As I mentioned on page 198, most animal species occupy a geographic range confined to a small fraction of the Earth's surface. Of those species occurring on several continents (such as lions and grizzly bears), it is not the case that individuals from one continent visit one another. Instead, each continent, and usually each small part of a continent, has its own distinctive population, in contact with close neighbours but not with distant members of the same species. (Migratory songbirds constitute an apparently glaring exception. But while they do commute seasonally between continents, it is only along a traditional path, and both the summer breeding range and the winter non-breeding range of a given population tend to be quite circumscribed.) This geographic fidelity of animals is reflected in the geographic variability that I discussed in Chapter Six. Populations of the same species in different geographic areas tend to evolve into different-looking subspecies, because most breeding remains within the same population. For example, no gorilla of the East African lowland subspecies has ever turned up in West Africa or vice versa, though the eastern and western subspecies look, sufficiently different that biologists could recognize a wanderer if there were any.
In these respects, we humans have been typical animals throughout most of our evolutionary history. Like other animals, each human population is genetically moulded to its area's climate and diseases, but human populations are also impeded from freely mixing by linguistic and cultural barriers far stronger than in other animals. As mentioned in Chapter Six, an anthropologist can identify roughly where a person originates from the person's naked appearance, and a linguist or student of dress styles can pinpoint origins much more closely. That is testimony to how sedentary human populations have been.
While we think of ourselves as travellers, we were quite the opposite throughout several million years of human evolution. Every human group was ignorant of the world beyond its own lands and those of its immediate neighbours. Only in recent millenia did changes in political organization and technology permit some people routinely to travel afar, to encounter distant peoples, and to learn first-hand about places and peoples that they had not personally visited. This process accelerated with Columbus's voyage of 1492, until today there remain only a few tribes in New Guinea and South America still awaiting first contact with remote outsiders. The Archbold Expedition's entry into the Grand Valley will be remembered as one of the last first contacts of a large human population. It was thus a landmark in the process by which humanity became transformed from thousands of tiny societies, collectively occupying only a fraction of the globe, to world conquerors with world knowledge. How could such a numerous people as the Grand Valley's 50,000 Papuans remain completely unknown to outsiders until 1938? How could those Papuans in turn remain completely ignorant of the outside world? How did first contact change human societies? I shall argue that this World before first contact—a world that is finally ending within our own generation—holds a key to the origins of human cultural diversity. As World conquerors, our species now numbers over five billion, compared to the mere ten million people who existed before the advent of agriculture. Ironically, though, our cultural diversity has plunged even as our numbers have soared.