It is worth re-iterating here that, in this book, we are not concerned with the massive cultural explosions that followed, of which the naked ape of today is so proud—the dramatic progression that led him, in a mere half-million years, from making a fire to making a space-craft. It is an exciting story, but the naked ape is in danger of being dazzled by it all and forgetting that beneath the surface gloss he is still very much a primate. (‘An ape’s an ape, a varlet’s a varlet, though they be clad in silk or scarlet.’) Even a space ape must urinate.
Only by taking a hard look at the way in which we have originated and then by studying the biological aspects of the way we behave as a species today, can we really acquire a balanced, objective understanding of our extraordinary existence.
If we accept the history of our evolution as it has been outlined here, then one fact stands out clearly: namely, that we have arisen essentially as primate predators. Amongst existing monkeys and apes, this makes us unique, but major conversions of this kind are not unknown in other groups. The giant panda, for instance, is a perfect case of the reverse process. Whereas we are vegetarians turned carnivores, the panda is a carnivore turned vegetarian, and like us it is in many ways an extraordinary and unique creature. The point is that a major switch of this sort produces an animal with a dual personality. Once over the threshold, it plunges into its new role with great evolutionary energy—so much so that it carries with it many of its old traits. Insufficient time has passed for it to throw off all its old characteristics while it is hurriedly donning the new ones. When the ancient fishes first conquered dry land, their new terrestrial qualities raced ahead while they continued to drag their old watery ones with them. It takes millions of years to perfect a dramatically new animal model, and the pioneer forms are usually very odd mixtures indeed. The naked ape is such a mixture. His whole body, his way of life, was geared to a forest existence, and then suddenly (suddenly in evolutionary terms) he was jettisoned into a world where he could survive only if he began to live like a brainy, weapon-toting wolf. We must examine now exactly how this affected not only his body, but especially his behaviour, and in what form we experience the influence of this legacy at the present day. One way of doing this is to compare the structure and the way of life of a ‘pure’ fruit-picking primate with a ‘pure’ carnivore. Once we have cleared our minds about the essential differences that relate to their two contrasted methods of feeding, we can then re-examine the naked ape situation to see how the mixture has been worked out.
The brightest stars in the carnivore galaxy are, on the one hand, the wild dogs and wolves, and, on the other, the big cats such as the lions, tigers and leopards. They are beautifully equipped with delicately perfected sense organs. Their sense of hearing is acute, and their external ears can twist this way and that to pick up the slightest rustle or snort. Their eyes, although poor on static detail and colour, are incredibly responsive to the tiniest movement. Their sense of smell is so good that it is difficult for us to comprehend it. They must be able to experience a virtual landscape of odours. Not only are they capable of detecting an individual smell with unerring precision, but they are also able to pick out the separate component odours of a complex smell. Experiments carried out with dogs in 1953 indicated that their sense of smell was between a million and a thousand million times as accurate as ours. These astonishing results have since been queried, and later, more careful tests have not been able to confirm them, but even the most cautious estimates put the dog’s sense of smell at about a hundred times better than ours.
In addition to this first-rate sensory equipment; the wild dogs and big cats have a wonderfully athletic physique. The cats have specialised as lightning sprinters, the dogs as long-distance runners of great stamina. At the kill they can bring into action powerful jaws, sharp, savage teeth and, in the case of big cats, massively muscular front limbs armed with huge, dagger-pointed claws.
For these animals, the act of killing has become a goal in itself, a consummatory act. It is true that they seldom kill wantonly or wastefully, but if, in captivity, one of these carnivores is given ready-killed food, its urge to hunt is far from satisfied. Every time a domestic dog is taken for a walk by its master, or has a stick thrown for it to chase and catch, it is having its basic need to hunt catered for in a way that no amount of canned dog-food will subdue. Even the most overstuffed domestic cat demands a nocturnal prowl and the chance to leap on an unsuspecting bird.
Their digestive system is geared to accept comparatively long periods of fasting followed by bloating gorges. (A wolf, for instance, can eat one-fifth of its total body weight at one meal—the equivalent of you or me devouring a 30—40 lb. steak at a single sitting.) Their food is of high nutritional value and there is little wastage. Their faeces, however, are messy and smelly and defecation involves special behaviour patterns. In some cases the faeces are actually buried and the site carefully covered over. In others, the act of defecating is always carried out at a considerable distance from the home base. When young cubs foul the den, the faeces are eaten by the mother and the home is kept clean in this way.
Simple food storage is undertaken. Carcasses, or parts of them, may be buried, as with dogs and certain kinds of cats; or they may be carried up into a treelarder, as with the leopard. The periods of intensive athletic activity during the hunting and killing phases are interspersed with periods of great laziness and relaxation. During social encounters the savage weapons so vital to the kill constitute a potential threat to life and limb in any minor disputes and rivalries. If two wolves or two lions fall out, they are both so heavily armed that fighting could easily, in a matter of seconds, lead to mutilation or death. This could seriously endanger the survival of the species and during the long course of the evolution that gave these species their lethal prey-killing weapons, they have of necessity also developed powerful inhibitions about using their weapons on other members of their own species. These inhibitions appear to have a specific genetic basis: they do not have to be learned. Special submissive postures have been evolved which automatically appease a dominant animal and inhibit its attack. The possession of these signals is a vital part of the way of life of the ‘pure’ carnivores.
The actual method of hunting varies from species to species. In the leopard it is a matter of solitary stalking or hiding, and a last-minute pounce. For the cheetah it is a careful prowl followed by an all-out sprint. For the lion it is usually a group action, with the prey driven in panic by one lion towards others in hiding. For a pack of wolves it may involve an encircling maneuver followed by a group kill. For a pack of African hunting dogs it is typically a ruthless drive, with one dog after another going in to the attack until the fleeing prey is weakened from loss of blood.
Recent studies in Africa have revealed that the spotted hyaena is also a savage packhunter and not, as has always been thought, primarily a scavenger. The mistake has been made because hyaena packs form only at night and minor scavenging has always been recorded during the day. When dusk falls, the hyaena becomes a ruthless killer, just as efficient as the hunting dog is during the day. Up to thirty animals may hunt together. They easily out-pace the zebras or antelopes they are pursing, which dare not travel at their full day-time speeds. The hyaenas start tearing at the legs of any prey in reach until one is sufficiently wounded to fall back from the fleeing herd. All the hyaenas then converge on this one, tearing out its soft parts until it drops and is killed. Hyaenas base themselves at communal den-sites. The group or ‘clan’ using this home base may number between ten and a hundred. Females stick closely to the area around this base, but the males are more mobile and may wander off into other regions. There is considerable aggression between clans if wandering individuals are caught off their own clan territory, but there is little aggression between the members of any one clan.
Food-sharing is known to be practised in a number of species. Of course, at a large kill there is meat enough for the whole hunting group and there need be little squabbling, but in some instances the sharing is taken further than that. African hunting dogs, for instance, are known to regurgitate food to one another after a hunt is over. In some cases they have done this to such an extent that they have been referred to as having a ‘communal stomach’.
Carnivores with young go to considerable trouble to provide food for their growing offspring. Lionesses will hunt and carry meat back to the den, or they will swallow large hunks of it and then regurgitate it for the cubs.
Male lions have occasionally been reported to assist in this matter, but it does not appear to be a common practice. Male wolves, on the other hand, have been known to travel up to fifteen miles to obtain food for both the female and her young. Large meaty bones may be carried back for the young to gnaw, or hunks of meat may be swallowed at the kill and then regurgitated at the entrance to the den.
These, then, are some of the main features of the specialist carnivores, as they relate to their hunting way of life. How do they compare with those of the typical fruit-picking monkeys and apes?
The sensory equipment of the higher primates is much more dominated by the sense of vision than the sense of smell. In their tree-climbing world, seeing well is far more important than smelling well, and the snout has shrunk considerably, giving the eyes a much better view. In searching for food, the colours of fruits are helpful clues, and, unlike the carnivores, primates have evolved good colour vision. Their eyes are also better at picking out static details. Their food is static, and detecting minute movements is less vital than recognising subtle differences in shape and texture. Hearing is important, but less so than for the tracking killers, and their external ears are smaller and lack the twisting mobility of those of the carnivores. The sense of taste is more refined. The diet is more varied and highly flavoured—there is more to taste. In particular there is a strong positive response to sweet-tasting objects.
The primate physique is good for climbing and clambering, but it is not built for highspeed sprinting on the ground, or for lengthy endurance feats. This is the agile body of an acrobat rather than the burly frame of a powerful athlete. The hands are good for grasping, but not for tearing or striking. The jaws and teeth are reasonably strong, but nothing like the massive, clamping, crunching apparatus of the carnivores. The occasional killing of small, insignificant prey requires no gargantuan efforts. Killing is not, in fact, a basic part of the primate way of life.
Feeding is spread out through much of the day. Instead of great gorging feasts followed by long fasts, the monkeys and apes keep on and on munching a life of nonstop snacks. There are, of course, periods of rest, typically in the middle of the day and during the night, but the contrast is nevertheless a striking one. The static food is always there, just waiting to be plucked and eaten. All that is necessary is for the animals to move from one feeding-place to another, as their tastes change, or as the fruits come in and out of season. No food storage takes place except, in a very temporary way, in the bulging cheek pouches of certain monkeys.
The faeces are less smelly than those of the meat-eaters and no special behaviour has developed to deal with their disposal, since they drop down out of the trees and away from the animals. As the group is always on the move, there is little danger of a particular area becoming unduly fouled or smelly. Even the great apes that bed down in special sleeping-nests make a new bed at a new site each night, so that there is little need to worry about nest sanitation. (All the same, it is rather surprising to discover that 99 per cent of abandoned gorilla nests in one area of Africa had gorilla dung inside them, and that in 73 per cent the animals had actually been lying in it. This is bound to constitute a disease risk by increasing the chances of re-infection, and is a remarkable illustration of the basic faecal disinterest of primates.)
Because of the static nature and abundance of the food, there is no need for the primate group to split up to search for it. They can move, flee, rest and sleep together in a close-knit community, with every member keeping an eye on the movements and actions of every other. Each individual of the group will at any one moment have a reasonably good idea of what everyone else is doing. This is a very non-carnivore procedure. Even in those species of primates that do split up from time to time, the smaller unit is never composed of a single individual. A solitary monkey or ape is a vulnerable creature. It lacks the powerful natural weapons of the carnivore and in isolation falls easy prey to the stalking killers.
The co-operative spirit that is present in such pack-hunters as wolves is largely absent from the world of the primate. Competitiveness and dominance is the order of his day. Competition in the social hierarchy is, of course, present in both groups, but it is less tempered by co-operative action in the case of monkeys and apes. Complicated, coordinated manoeuvres are also unnecessary: sequences of feeding action do not need to be strung together in such a complex way. The primate can live much more from minute to minute, from hand to mouth.
Because the primate’s food supply is all around it for the taking, there is little need to cover great distances. Groups of wild gorillas, the largest of the living primates, have been carefully studied and their movements traced, so that we now know that they travel on the average about a third of a mile a day. Sometimes they move only a few hundred feet. Carnivores, by contrast, must frequently travel many miles on a single hunting trip. In some instances they have been known to travel over fifty miles on a hunting journey, taking several days before returning to their home base. This act of returning to a fixed home base is typical of the carnivores, but is far less common amongst the monkeys and apes. True, a group of primates will live in a reasonably clearly defined home range, but at night it will probably bed down wherever it happens to have ended up in its day’s meanderings. It will get to know the general region in which it lives because it is always wandering back and forth across it, but it will tend to use the whole area in a much more haphazard way. Also, the interaction between one troop and the next will be less defensive and less aggressive than is the case with carnivores. A territory is, by definition, a defended area, and primates are not therefore, typically, territorial animals.