Because hearts pump blood, and not for any reason related to the other facts. Some recent philosophers have gone so far as to say that only natural selection can produce things with final causes, purposes. Science and philosophy. Darwin argues that many of these have precursors in non-human animals. He deals in detail with the first three.
Morality is species-relative.
Sensitivity to praise and blame by others. The universal morality of good will to all is an accidental by-product of the expansion of human reason and imagination, working on these raw materials. Long periods of stasis, punctuated by brief, rapid episodes of change. Aiming at a moving target. Raises the issue of eugenics, and of genetic re-engineering.