Chimpanzees have both opposable big toes and opposable thumbs. Most primates have nine wrist bones. Humans, chimps and gorillas have eight; two have fused, stabilising the wrist for knuckle-walking. | Chimpanzees have both opposable big toes and opposable thumbs. Most primates have nine wrist bones. Humans, chimps and gorillas have eight; two have fused, stabilising the wrist for knuckle-walking. |