Your article reports that, after infancy, humans have trouble recognizing facial differences between members of other species. Many of us commonly observe that people of other races than ourselves “all look alike” to us. Could this stem from lack of early exposure to others? Anecdotally, my wife, raised in a multiracial environment, has far less problem recognizing individuals of other races than do I, who was raised in essentially a one-race environment.

Clark Waite
Descanso, Calif.