Baboons are found as far north as the semidesert
of Saudi Arabia (Papio hamadryas) and
as far south as Cape Town in South Africa (P. cynocephalus
ursinus). The regional variants of the
cynocephalus (dog-headed) baboon (chacma in
the south, Guinea in the west, olive in the north
east, and yellow baboon in the southeast) are considered
to be the same species by most experts.
The northeastern variant, the hamadryas, is generally
considered to be a separate species but can
interbreed with the olive baboon of Ethiopia.
Baboons and Their Environment
Baboons are very numerous in Africa, and are
among the most adaptable of all mammals. This
adaptability also allows baboons to survive in wet
forest and the driest semidesert regions. They eat
almost any plant material or small animal they encounter.
Baboons often survive quite well in and
around human settlements. They sometimes
cause severe crop damage when they visit farmers'
fields, since they are capable of eating even the
toughest roots, such as cassava and sweet potato,
but they also forage on farmers' bananas and
maize. Baboons can survive on garbage at tourist
lodges, or find food in near deserts in Namibia,
Ethiopia, and Saudi Arabia. Baboons sleep in trees
or caves and cliff ledges, for protection from nocturnal
predators.
Baboon Society
Except in the driest and coldest habitats, baboons
form large groups and travel widely in the course
of a day. Groups often exceed one hundred animals
and contain scores of juveniles and females,
plus a few adult males. These large social groups
are composed of matrilines-a kin-group of sisters
and their daughterswhoall descend fromone
female, plus their infant and juvenile male offspring-
and unrelated adult males, who compete
for mating access to females with sexual swellings.
Alarge group can contain several matrilines,
which may compete with each other over access
to food, shelter, and male protection. The adult
males in the group often fight fiercely among
themselves, using coalitions to overcome single
competitors. The typically calm life of moving in
search of food is regularly interrupted by squabbles
and mild competition over resources. More
rarely, large fights break out within groups, and
injuries follow. The most severe aggression is seen
when a new adult male immigrates into a group,
fights the other males to obtain high rank, and
even harasses females and their young. Some
cases of infanticide have been reported in such circumstances.
The hamadryas baboons differ most
in social organization. They do not build matrilines
based on female kinship, but rather a female
leaves the group in which she was born and bonds
to a particular male as her future mate. This male
plays an important social role as protector of a
small group of one to three females. These small,
one-male units travel and forage independently
most of the time, but reunite with other units at
night to form large herds often numbering in the
hundreds.
Baboons have been studied extensively by biomedical
researchers because of their physiological
similarities to humans and because they are common
animals in Africa. Baboons have also been
studied intensively by anthropologists and evolutionary
biologists interested in human origins.
That is because the baboon evolved from an arboreal
monkey that first exploited dry, open habitats
some ten to twenty-five million years ago. In the
past, anthropological theory suggested that our
own ancestors followed a similar evolutionary
pathway. Thus, baboons were seen for some time
as a useful model for human evolution. This idea
has changed somewhat over time as scientists
have found that the group sizes, social organizations,
and dietary habits of baboons probably do
not mirror those of our ancestors. A more recent
view holds that we can learn about antipredator
behavior and habitat selection of our ancestors by
observing baboons in similar habitats today.
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