The only humans survived were those, who liked baby animals. Because that humans domesticated wolfs, horses and so on, which gave them the superiority above other humans.
I assume, that everything what exist, should be approved by evolution somehow. Hence, IF humans actually likes baby animals, THEN it should be approved.
So, I remembered, that humans were domesticating animals and this technology was helping them (us) to survive. Also I remembered, that domestication is usually started with adoption of animal babies. Adoption was occurring by chance, on the basis of non-motivated congenital (genetic) love to baby animals.
So, my explanation is: some of human species were liking animal babies and this caused domestication. Then domestication caused evolution advantages, and these species won the competition with other human species. We are descendants of former species and conserve our sympathies to baby animals. Those who were not liking them -- died millions years ago.