Baboon

In 2015 researchers found the oldest baboon fossil on record, dated at 2 million years old.[9]

Baboons are terrestrial (ground dwelling) and are found in open savannah, open woodland and hills across Africa. They are omnivorous, highly opportunistic feeders and will eat virtually anything, including grasses, roots, seeds, leaves, bark, fruits, fungus, insects, spiders, worms, fish, shellfish, rodents, birds, vervet monkeys, and small antelopes.[11] They are foragers and are active at irregular times throughout the day and night. They often raid human dwellings, and in South Africa they break into homes and cars in search of food. Baboons will also raid farms, eating crops and preying on sheep, goats and poultry.

Their principal predators are Nile crocodiles, lions, spotted and striped hyenas, and leopards.[12][13] They are considered a difficult prey for the leopard, though, which is mostly a threat to young baboons. Large males will often confront them by flashing their eyelids, showing their teeth by yawning, making gestures, and chasing after the intruder/predator. Although they are not a prey species, baboons have been killed by the black mamba snake. This usually occurs when a baboon accidentally rouses the snake.[14]

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  Baboons caught up a tree by Kalahari lions (1 of 3)
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  Baboons caught up a tree by Kalahari lions (2 of 3)
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  Baboons caught up a tree by Kalahari lions (3 of 3)

A troop of baboons

The collective noun for baboons is "troop".[15] Most baboons live in hierarchical troops. Group sizes are typically around 50 animals, but can vary between 5 and 250, depending on species, location and time of year. The structure within the troop varies considerably between hamadryas baboons and the remaining species, sometimes collectively referred to as savanna baboons. The hamadryas baboons often appear in very large groups composed of many smaller harems (one male with four or so females), to which females from elsewhere in the troop are recruited while they are still too young to breed. Other baboon species have a more promiscuous structure with a strict dominance hierarchy based on the matriline. The hamadryas baboon group will typically include a younger male, but he will not attempt to mate with the females unless the older male is removed. In the harems of the hamadryas baboons, the males jealously guard their females, to the point of grabbing and biting the females when they wander too far away. Despite this, some males will raid harems for females. Such situations often cause aggressive fights between the males. Visual threats usually accompany these aggressive fights. These include a quick flashing of the eyelids accompanied by a yawn to show off the teeth. Some males succeed in taking a female from another's harem, called a "takeover". In several species, infant baboons are taken by the males as hostages, or used as shields during fights.

Baboons can determine from vocal exchanges what the dominance relations are between individuals. When a confrontation occurs between different families or where a lower-ranking baboon takes the offensive, baboons show more interest in this exchange than those between members of the same family or when a higher-ranking baboon takes the offensive. This is because confrontations between different families or rank challenges can have a wider impact on the whole troop than an internal conflict in a family or a baboon reinforcing its dominance.[16]

Baboon social dynamics can also vary; Robert Sapolsky reported on a troop, known as the Forest Troop, during the 1980s, which experienced significantly less aggressive social dynamics after its most aggressive males died off during a tuberculosis outbreak, leaving a skewed gender ratio of majority females and a minority of low-aggression males. This relatively low-aggression culture persisted into the 1990s and extended to new males coming into the troop, though Sapolsky observed that while unique, the troop was not an "unrecognizably different utopia"; there was still a dominance hierarchy and aggressive intrasexual competition amongst males. Furthermore, no new behaviours were created amongst the baboons, rather the difference was the frequency and context of existing baboon behaviour.[17]

Chacma baboons mating at Cape Point in South Africa

Baboon mating behavior varies greatly depending on the social structure of the troop. In the mixed groups of savanna baboons, each male can mate with any female. The mating order among the males depends partially on their social ranking, and fights between males are not unusual. There are, however, more subtle possibilities; in mixed groups, males sometimes try to win the friendship of females. To garner this friendship, they may help groom the female, help care for her young, or supply her with food. The probability is high that those young are their offspring. Some females clearly prefer such friendly males as mates. However, males will also take infants during fights to protect themselves from harm. A female initiates mating by presenting her swollen rump to the male's face.[18]

In a wild baboon population of the Amboseli ecosystem in Kenya, inbreeding is avoided by mate choice.[19] Inbreeding avoidance through mate choice is thought to only evolve when related possible sexual partners frequently encounter each other and there is a risk of inbreeding depression.[20]

Young Olive baboon on the back of its mother, Lake Manyara National Park, Tanzania

Females typically give birth after a six-month gestation, usually to a single infant; twin baboons are rare and often do not survive. The young baboon weighs approximately 400 g and has a black epidermis when born.

The females tend to be the primary caretaker of the young, although several females will share the duties for all of their offspring. After about one year, the young animals are weaned. They reach sexual maturity in five to eight years. Baboon males leave their birth group, usually before they reach sexual maturity, whereas females are philopatric and stay in the same group their whole lives.

Baboons in captivity have been known to live up to 45 years, while in the wild their life expectancy is between 20 to 30 years.