All baboons have long dog-like muzzles (cynocephalus = dog-head), close-set eyes, heavy powerful jaws, thick fur except on their muzzle, short tail and often brightly coloured ischial callosities. Baboons are terrestrial (ground dwelling) and are found in savanna, open woodland and hills across Africa. Their diet is omnivorous, but usually vegetarian - they are foragers and are active at irregular times throughout the day and night. They can raid human dwellings and in South Africa they have been known to prey on sheep and goats.
Baboons live in hierarchical troops of 5 to 250 animals (50 or so is common), depending on species and time of year. They can live as long as thirty years.
Their principal predators are man and the leopard, although they are tough prey for a leopard and large males will often confront them.
There are five recognised races of Papio, but whether they should be regarded as full species, or as subspecies, is debatable. They are ursinus (Chacma baboon, found in southern Africa), papio (Guinea or Western baboon, found in Senegal, The Gambia, Guinea), hamadryas (Hamadryas baboon, found in north-east Africa and into south-western Arabia), anubis (Olive baboon, found in central African savanna) and cynocephalus (Yellow baboon, found in Angola, Zambia, Malawi, Tanzania, Kenya, Somalia). Many authors distinguish P. hamadryas as a full species, but regard all the others as subspecies of P. papio and refer to them collectively as "savanna baboons"; even between hamadryas and the neighbouring savanna populations there is a stable zone of hybridisation.
There is considerable variation in size and weigh depending on species, the Chacma baboon can be 120 cm and weigh 40 kg while the biggest Guinea baboon is 50 cm and weighs only 14 kg, in all baboon species there is pronounced sexual dimorphism usually in size but also maybe in colour or canine development.
The Hamadryas baboon was a sacred animal to the ancient Egyptians as the attendant of Thoth.
The following was originally from the 1911 Encyclopedia Britannica.
BABOON (from the Fr. babuin, which is itself derived from Babon, the Egyptian deity to whom it was sacred), properly the designation of the long-muzzled, medium-tailed Egyptian monkey, scientifically known as Papio anubis; in a wider sense applied to all the members of the genus Papio (formerly known as Cynocephalus) now confined to Africa and Arabia, although in past times extending into India. Baboons are for the most part large terrestrial monkeys with short or medium-sized tails, and long naked dog-like muzzless, in the truncated extremity of which are pierced the nostrils. As a rule, they frequent barren rocky districts in large droves, and are exceedingly fierce and dangerous to approach. They have large cheek-pouches, large naked callosities, often brightly coloured, on the buttocks, and short thick limbs, adapted rather to walking than to climbing. Their diet includes practically everything eatable they can capture or kill. The typical representative of the genus is the yellow baboon (P. cynocephalus, or babuin), distinguished by its small size and grooved muzzle, and ranging from Abyssinia to the Zambezi. The above-mentioned anubis baboon, P. anubis (with the subspecies neumanni, pruinosus, heuglini and doguera), ranging from Egypt all through tropical Africa, together with P. sphinx, P. olivaceys, the Abyssinian P. lydekkeri, and the chacma, P. porcarius of the Cape, represent the subgenus Choeropithecus. The named Arabian baboon, P. hamadryas of North Africa and Arabia, dedicated by the ancient Egyptians to the god Thoth, and the South Arabian P. arabicus, typify Hamadryas; while the drill and mandrill of the west coast, P. leucophaeus and P. maimon, constitute the subgenus Maimon. The anubis baboons, as shown by the frescoes, were tamed by the ancient Egyptians and trained to pluck sycamore-figs from the trees.