Re: This would make them less
It's simply stating a scientific belief that a million years ago, some babies could not recognise their parents' faces and as a result smiled less and were loved less. That made them less likely to survive.
The writer has chosen to use "This would make them ..." instead of "This made them ...". You would have to ask him/her why.
The same can be said for the closing sentence. There is no reason to use "It would seem that ..." instead of "It seems that ..."
It suggests a tiny amount of questionability in the statement perhaps. "It seems that ..." sounds quite certain. "It would seem ..." sounds perhaps a little more hesitant.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.