Question

Gibbons both walk on their hindlimbs and “brachiate” hand over hand. The total weight supported is obviously the same in either case. Suggest why it is functionally reasonable for their arm bones to be more slender than their leg bones. The arm and leg bones are approximately the same length.

Answer 1

In gibbons, the arm bones are more slender as compared to the leg bones because they are arboreal in nature and since they spend most of their time in the trees, the slender and long arms give them flexibility to hold the branches of the trees and maintain the stability and balance while moving around amongst the trees. They are able to swing from branch to branch and this is known as brachiating and they use their four fingers in form of hook as they swing from branch to branch. The slender and longer arms gives them strength to walk on the branch and also helps in maintaining the balance.