Éléphants, miroirs des Hommes

Parlons Futur

Meilleurs extraits de l'article de The Economist Conserve elephants. They hold a scientific mirror up to humans

Elephants, about as unrelated to human beings as any mammal can be, seem nevertheless to have evolved intelligence, and possibly even consciousness. Though they may not be alone in this (similar claims are made for certain whales, social carnivores and a few birds), they are certainly part of a small and select group. Losing even one example of how intelligence comes about and makes its living in the wild would not only be a shame in its own right, it would also diminish the ability of biologists of the future to understand the process, and thus how it happened to human beings.

Dr Wittemyer argues that, human beings aside, no species on Earth has a more complex society than that of elephants. And elephant society does indeed have parallels with the way humans lived before the invention of agriculture. The nuclei of their social arrangements are groups of four or five females and their young that are led by a matriarch who is mother, grandmother, great-grandmother, sister or aunt to most of them. Though males depart their natal group when maturity beckons at the age of 12, females usually remain in it throughout their lives. Families are part of wider “kinship” groups that come together and separate as the fancy takes them. Families commune with each other in this way about 10% of the time. On top of this, each kinship group is part of what Dr Douglas-Hamilton, a Scot, calls a clan. Clans tend to gather in the dry season, when the amount of habitat capable of supporting elephants is restricted. Within a clan, relations are generally friendly. All clan members are known to one another and, since a clan will usually have at least 100 adult members, and may have twice that, this means an adult (an adult female, at least) can recognise and have meaningful social relations with that many other individuals. A figure of between 100 and 200 acquaintances is similar to the number of people with whom a human being can maintain a meaningful social relationship—a value known as Dunbar’s number, after Robin Dunbar, the psychologist who proposed it. Dunbar’s number for people is about 150. It is probably no coincidence that this reflects the maximum size of the human clans of those who make their living by hunting and gathering, and who spend most of their lives in smaller groups of relatives, separated from other clan members, scouring the landscape for food. Dealing with so many peers, and remembering details of such large ranges, means elephants require enormous memories. Details of how their brains work are, beyond matters of basic anatomy, rather sketchy. But one thing which is known is that they have big hippocampuses. These structures, one in each cerebral hemisphere, are involved in the formation of long-term memories. Compared with the size of its brain, an elephant’s hippocampuses are about 40% larger than those of a human being, suggesting that the old proverb about an elephant never forgetting may have a grain of truth in it. In the field, the value of the memories thus stored increases with age. Matriarchs, usually the oldest elephant in a family group, know a lot. The studies in Amboseli and Samburu have shown that, in times of trouble such as a local drought, this knowledge permits them to lead their groups to other, richer pastures visited in the past. Though not actively taught (at least, as far as is known) such geographical information is passed down the generations by experience. Indeed, elephant biologists believe the ability of the young to benefit by and learn from the wisdom of the old is one of the most important reasons for the existence of groups—another thing elephants share with people. Nor is it only in their social arrangements that elephants show signs of parallel evolution with humans. They also seem to have a capacity for solving problems by thinking about them in abstract terms. This is hard to demonstrate in the wild, for any evidence is necessarily anecdotal. But experiments conducted on domesticated Asian elephants (easier to deal with than African ones) show that they can use novel objects as tools to obtain out-of-reach food without trial and error beforehand. This is a trick some other species, such as great apes, can manage, but which most animals find impossible. Wild elephants engage in one type of behaviour in particular that leaves many observers unable to resist drawing human parallels. This is their reaction to their dead. Elephant corpses are centres of attraction for living elephants. They will visit them repeatedly, sniffing them with their trunks and rumbling as they do so (see picture overleaf). This is a species-specific response; elephants show no interest in the dead of any other type of animal. And they also react to elephant bones, as well as bodies, as Dr Wittemyer has demonstrated. Prompted by the anecdotes of others, and his own observations that an elephant faced with such bones will often respond by scattering them, he laid out fields of bones in the bush. Wild elephants, he found, can distinguish their conspecifics’ skeletal remains from those of other species. And they do, indeed, pick them up and fling them into the bush.