Figure 14.23: Chimpanzees, pictured here, belong to the great apes, one of the groups of
primates. ( 27 )
cantsexual dimorphism,characterized mostly as size differences, with males being slightly
more than twice as heavy as females. This dimorphism may be a result of a polygamous
mating system where males attract and defend multiple females. New World species (in-
cluding tamarins((Figure14.26) and marmosets(Figure14.27)) form pair bonds, which is
a partnership between a mating pair that lasts at least one season. The pair cooperatively
raise the young, and thus generally do not show significant size difference between the sexes.
Non-human primates occur mostly in Central and South America, Africa and South Asia.
Since primates evolved from arboreal animals, many modern species live mostly in trees.
Otherspeciesarepartiallyterrestrial, suchasbaboons(Figure14.28)andthePatasmonkey.
Only a few species are fully terrestrial, for example, the gelada and humans.
Primatesliveinadiversenumberofforestedhabitats, includingrainforests, mangroveforests
and mountain forests to altitudes of over 9,800 ft (3,000 m). The combination of opposable
thumbs, short fingernails and long, inward-closing fingers has, in part, allowed some species
to develop brachiation, locomotion of swinging by arms from one branch to another (Figure
14.29). Another feature for climbing – expanded digits – as in tarsiers improves grasping
(Figure14.30).
Afewspecies, suchastheproboscismonkey, DeBrazza’smonkeyandAllen’sswampmonkey,
the latter having small webbing between its fingers, are fine swimmers and occur in swamps
and other aquatic habitats. Some species, such as the rhesus macaque and the Hanuman
langur, can exploit human-altered environments and even live in cities.