At the risk of doing another evo-psych just so story: Before you have reproduced putting any effort into helping babies diverts resources you could use for your own gains. Whereas after you’ve reproduced you need to keep your babies alive to pass on your genes. The increased affection for other peoples babies could be a side effect, or it might be beneficial in group environments where child care is shared.
1 year ago, I would have completely agreed.
Then we had a baby, and now I see cuteness in babies all over the place. None as cute as my baby, though.
At the risk of doing another evo-psych just so story: Before you have reproduced putting any effort into helping babies diverts resources you could use for your own gains. Whereas after you’ve reproduced you need to keep your babies alive to pass on your genes. The increased affection for other peoples babies could be a side effect, or it might be beneficial in group environments where child care is shared.