Brachiation

Brachiation (from "limb" or "branch") is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms.

Brachiators

The only true brachiators are the lesser apes (gibbons and siamangs). A gibbon can brachiate at speeds as high as 35 mph and can travel as far as 20 feet with each swing. Spider monkeys and orangutans are considered semibrachiators.

Brachiation-aiding traits

Some of the traits that allow gibbons, siamangs, and other primates to brachiate include the following: short fingernails instead of claws, inward-closing, hook-like fingers, opposable thumbs, long forelimbs, and freely rotating shoulder joints.

Brachiation and humans

Modern humans retain many physical characteristics that suggest a protobrachiator ancestor, including flexible shoulder joints and fingers well-suited for grasping. In apes, these characteristics were adaptations for brachiation. Although humans do not normally brachiate, our anatomy suggests that brachiation may be a preadaptation to bipedalism, and healthy modern humans are still capable of brachiating. Some children’s parks include monkey bars which children play on by brachiating.

References

# Rice, Patricia C.; Norah Moloney (2005). "Biological Anthropology and Prehistory: Exploring our Human Ancestry". Pearson Education, Inc., pp. 178-179, 192. ISBN 0205381960
# [http://www.britannica.com/ebc/article-9016092 Brittanica.com]
# [http://dictionary.reference.com/browse/brachiation Dictionary.com]
# [http://encarta.msn.com/encyclopedia_761566394_2/Human_Evolution.html#p303 MSN Encarta]