Indians in the northwest Amazon . . . possess a knowledge of the tropical forest that puts almost any biologist to shame. . . . at forty paces, their hunters can smell animal urine and distinguish on the basis of scent alone which out of dozens of possible species left it. Such sensitivity is not an innate attribute of these people, any more than technological prowess is something inevitably and uniquely ours. Both are consequences of adaptive choices that resulted in the development of highly specialized but different mental skills, at the obvious expense of others.