Some people might say that the fact that most noctuid moths have ultrasound-sensitive ears is “simply” a
reflection of their shared ancestry, a holdover from the past, and therefore that ultrasound sensitivity is
not an adaptation in these species (Brooks and McLennan 1991). Others disagree, arguing that it makes
no sense to define adaptations in a way that limits them to just those traits that have diverged from the
ancestral pattern (Reeve and Sherman 1993). Who is right?