were a uniquely human attribute. In fact, most primates have opposable thumbs. Ours are just more pliant and mobile. What we do have in our thumbs are three small but resplendently named muscles not found in any other animals, including chimps: the extensor pollicis brevis, the flexor pollicis longus, and the first volar interosseous of Henle.* Working together, they allow us to grasp and manipulate tools with sureness and delicacy. You might never have heard of them, but these three small muscles are at
