There have been several studies in the last 20 years of apes, such as gorilla and chimpanzee, living in their natural homes. Instead of watching their behaviour in captivity, observers have kept a record of the apes’ activities under natural conditions, perhaps spending years living alongside them. The results of these studies have greatly altered our views on the life of the apes and have given new insights into our own behaviour. Baboons have received considerable attention, one reason being that they often live in the open where they can be easily watched. These studies of baboons are important because they are of monkeys that have forsaken a life in the trees, and so may give us clues about how our ancestors made a similar move. Both must have faced the same problems of getting food and guarding against danger.
Baboons belong to the family of Old World monkeys. They inhabit most parts of Africa where they live in family groups, called troops. Smaller than chimpanzees and gorillas, they have long muzzles, and long tails, usually held in a characteristic inverted U.
Distribution and habitat
The chacma baboon lives in eastern and southern Africa, the yellow baboon in central Africa, the doguera baboon from Ethiopia to Kenya, and the Guinea baboon in west-central Africa. Gelada baboons, which are classified in a separate genus, are confined to the mountains of Ethiopia, while the hamadryas or sacred baboons are found farther north in Arabia, Egypt, the Sudan, Ethiopia and Somalia. They usually inhabit rocky open country or «bush», but also live in woodland.
It is the social structure of baboons, the organisation of the troops, that has attracted the interest of ethologists. Each troop is a family unit with all mating taking place between the members of that group. Typically, the troop consists of old males, juveniles, females and babies. In a small troop there may be no more than one male with two or three females and their babies, but large troops may number up to 50. In addition, several troops may gang together to form herds.
The troop, as we have said, is a discreet unit – the members never wander far from each other and have a definite range of countryside over which they wander, searching for food. At first sight, a troop of baboons appears to have little order, but on observation, a definite social structure can be seen. This is most clearly seen when a troop moves into open country. In the van come some of the smaller males followed by females and juveniles. In the middle of the troop there are the females carrying babies, the young juveniles, and rather surprisingly perhaps, the old, dominant males. The rear is brought up by more females and young males. The advantage of this is that the females and young are protected from all sides. Moreover, when danger threatens, the females and the very young start to flee first. The males move away more slowly, so they become congregated between the source of danger and the mothers and children.
A question that intrigued observers was how the troop kept together. It was known that in herds of antelopes, the males must constantly herd the members of their group to keep them together, but baboon families appeared to live amicably, the male having no need to force the others to stay with him. Nor were there many signs of violence except between the younger males. Observations showed that, in contrast with the antelopes, other baboons would actively congregate round the males. One behavioural trait that assists in holding the troop together is mutual grooming. This is the mammalian equivalent of allopreening, seen in such birds as the avadavats. When the troop is resting, or feeding quietly, they gather in small groups to groom each other’s fur. This keeps the fur clean, but, more important, it promotes harmony between the individuals. The grooming clusters usually form around a dominant male but other clusters form when the baboons gather round a female with a newborn infant, which is apparently of great interest to them. Human beings are not the only ones to indulge in baby worship!
To what extent there is a stronger bond than this between the members of a troop, it is difficult to say. Certainly it is essential for them to keep together as a protection against enemies, but, according to some observers, if a baboon is sick or injured its fellows will show concern for it, ensuring that it is not left behind when the troop is on the move. However, other observers report that no such consideration is shown. Presumably the presence or absence of such compassionate behaviour depends on circumstances, such as the amount of danger. In a given area and in sight of one observer, this might be sufficient to cause a troop to flee with scant regard for the weaker members. He would then record that baboons act on the principle of «the devil take the hindmost». The age of the injured baboon may also be important. The cry of a young one when hurt, for example, will bring the adults running to its aid, as in people.
Lion and leopard main enemies
Spending the day in the open and sleeping at night in trees, as baboons do, is a sound basis for defence. The tactics of a troop when faced by a predator, as described above, are reinforced by a warning system. While moving about and feeding, the troop keeps up a chorus of quiet grunts, but any one of them, on being disturbed, will give a shrill bark to alert its fellows. If a female gives the alarm, one of the males will then move away from the troop to keep the intruder under observation and will give a double bark whenever it moves.
The enemies of the baboon are cats, principally lions and leopards. Cheetahs and serval cats may try to prey on baboons but with less success than the other two. The usual reaction to attack is for the baboons to make for trees or rocks where, safe from attack, they bark defiance and even throw stones, but the old males are courageous and sometimes turn on their enemies, several old males being more than a match for any of their predators, whether lion or leopard.
Baboons breed throughout the year. When not pregnant or nursing, the females come on heat for a week in each month. Within the troop there is a hierarchy (or «peck order») among the males. There is usually one dominant male but sometimes several lower ranking males gang up to boss all the others. Moreover, all males are free to mate with receptive females. Pairings are temporary, but when the female is at the peak of oestrus she is guarded by the dominant male. Later, younger males mate with her.
The newborn baboon soon clings to the hair of its mother’s chest. Within hours of its birth it must have a sufficient grip to hang on even when the mother is leaping into the trees for safety. As it grows older it learns to ride on the mother’s back, jockey fashion, and soon after this it will begin eating solid foods and leaving the safety of its mother’s body. Its excursions become more and more adventurous until it meets other young baboons, and starts to play with them. However, if danger threatens all run straight to their respective mothers.
The play group of young baboons becomes a very important factor in their life. It is here they learn the skills needed for later life, in the form of games such as chasing and mock-fighting.
Baboons eat a wide variety of foods, both plant and animal, depending on season, local availability, and the age of the baboon. For instance, some troops of baboons feeding in woodlands were seen to split up. Females with babies sat on the ground eating grass heads, while the juveniles and the young males climbed to the tops of trees to eat the leaves, bark and insects not available to the larger animals.
Seeds, shoots, tubers, buds and fruit are all eaten in season and grasshoppers, butterflies and lizards are caught. Scorpions are a delicacy – the baboons nip off the stings with their fingers. Hares may be flushed out of their forms and chased, several baboons joining in to catch them. Occasionally small monkeys, such as vervets, are caught, and skinned before being eaten. Newborn Thompson’s gazelles, eggs and fledgling birds have been recorded as prey.
By tilling the soil, man has provided baboons with a plentiful supply of food, mainly in the form of fruit, and in many parts of Africa baboons have become a serious pest. Some of them develop a taste for milk, killing lambs and calves to get the milk in their stomachs.
A study by John Hurrell Crook has shown that the troop structure of gelada baboons in Ethiopia depended to some extent on the amount of food available. Where there was an abundance of food the troops were large and contained many males, but in the arid areas a troop would have only one male. This meant that the females who needed a plentiful supply of food for pregnancy and milk production, did not have to compete with males for the sparse supply. Yet the one male in the troop was sufficient to ensure procreation.
Jack the signalman
Before scientific studies on captive or wild monkeys and apes began, our knowledge of these animals was based more on anecdotes, casual stories about odd happenings. Even if these are not embellished to improve the story, anecdotes tend to give an overestimate of apes’ intelligence because they rarely deal with commonplace everyday events. One such story concerns a pet baboon belonging to a signalman in South Africa at the end of the last century. The Bushmen of South Africa claim that baboons can talk but take care not to let the white men hear them in case they are put to work. In fact this is precisely what did happen to the signalman’s baboon, Jack. He learnt to perform several jobs for his crippled master who had a wooden leg. First, he learnt to put the little trolley his master used to get to the signal box, onto the rails, and then push his master to work. Then he learnt to operate the signal levers, even getting to know at which moment to work them. It was even claimed that he took the initiative, learning to do jobs by watching his master and performing them of his own accord. Perhaps the best story is one that shows his powers of reasoning. One day Jack had been up to some mischief and was about to be punished. He quickly snatched his master’s stick and threw it away. A man with wooden legs in those days had no chance of chasing and chastising a baboon!