[Certain]

http://www.slate.com/articles/health...himpanzee.html

Repeated tests in the 1960s confirmed this basic picture. A chimpanzee had, pound for pound, as much as twice the strength of a human when it came to pulling weights. The apes beat us in leg strength, too, despite our reliance on our legs for locomotion. A 2006 study found that bonobos can jump one-third higher than top-level human athletes, and bonobo legs generate as much force as humans nearly two times heavier.