Biologists' current habit of explaining each feature of human life separately through its evolutionary function – its assumed tendency to enhance each individual's reproductive prospects – is unworkable. It also sits oddly with these scientists' official rejection of teleology, since it treats all life as a process which does have an aim, namely, to perpetuate itself. But that aim is empty because it is circular.
If we want to understand the behaviour of living things (including humans) we have to treat them seriously as subjects, creatures with needs, tendencies and directions of their own. The supposedly objective idea of a world of objects without subjects is an unprofitable fantasy.