Why do gibbons brachiate

When gibbons walk, whether along branches or in the rare instances when they descend to the ground, they often do so on two feet, throwing their arms above their head for balance. They are the most bipedal of all non-human primates and are often studied for clues to what evolutionary pressures may have led to human walking. There are over a dozen recognized species of gibbons ranging from northeastern India to southern China to Borneo.

They are all tailless, and their long coats vary from cream to brown to black. Many have white markings on their faces, hands, and feet. The largest species are known as siamangs, and can grow to 29 pounds. Smaller species reach only about nine pounds. Gibbons thrive on the abundant fruit trees in their tropical range, and are especially fond of figs. They will occasionally supplement their diet with leaves and insects. Gibbons are monogamous a rare trait among primates and live in family groups consisting of an adult pair and their young offspring.

The family will stake out a territory and defend it using loud, haunting calls that can echo for miles throughout the forest. Mated pairs, and even whole families, will sing long, complex songs together. Some species have even adapted large throat pouches to amplify their calls.

These iconic tree dwellers are among the most threatened primates on Earth. Their habitat is disappearing at a rapid rate, and they are often captured and sold as pets or killed for use in traditional medicines. Many species of gibbon are listed as endangered or critically endangered. All rights reserved. Common Name: Gibbons. Scientific Name: Hylobatidae. Type: Mammals. Diet: Omnivore. Group Name: Family. Size: 17 to 25 inches. Weight: 9 to 29 pounds. Size relative to a 6-ft man:.

This photo was submitted to Your Shot, our photo community on Instagram. Follow us on Instagram at natgeoyourshot or visit us at natgeo. Share Tweet Email. Go Further. Animals Wild Cities This wild African cat has adapted to life in a big city. When an animal sits on a branch, its own weight lowers the branch and makes feeding from that branch more difficult.

In contrast, the weight of a gibbon hanging below the branch serves to pull the branch towards the gibbon, which makes food collection easier Figure 5. Figure 5. White-handed gibbon H. Radius of action during feeding: a. Brachiation allows for very fast movement. It also enables gibbons to cross quite large gaps in the canopy, and the body weight can be distributed on branches that are relatively far apart.

In a suspensory position, a gibbon hanging from hook-like hands is always in a stable equilibrium, whereas primates standing on legs usually have to invest energy to keep the balance. Anatomical adaptations for brachiation occur mainly in the upper body parts. The long, hook-like hands and very long, strong finger-flexors help carry the weight of the body during swinging.

The most conspicuous adaption are the exceptionally long arms. They allow for a quick start and a high acceleration. The movement of the gibbon's body during brachiation resembles that of a pendulum and is subjected to similar physical forces.

The additional rotation of the body during brachiation produces high torsion loads in the upper arms. In order to counter these to some degree, the ball joint of the upper arm does not face as far forward as in humans and the other apes. As a result of the moderately expressed torsion in the gibbon humerus, the arms are hanging in a more lateral direction in the resting position Figure 5. Because of the moderately expressed torsion in the gibbon humerus, the arm appears to be laterally rotated away from the body after Larson, , pp.

Comparisons are often made between bipedal locomotion in humans and gibbons, in order to identify selection pressures which favor the evolution of upright walking.