New research coming out on the physiological changes men go through during their mate's pregnancy and after their child's birth, throws the idea that men aren't natural caretakers right out the window. Link />Although the research indicates that higher levels of testosterone will make the person less attentive, it also found that men's testosterone levels drop after the birth of their chlld, which seems to increase the amount of attention and affection they give to it.

Although this article didn't mention it specifically, I know that women's testosterone levels tend to increase during and after pregnancy and I wonder if this helps increase their energy levels for child rearing (because testosterone increases energy) or if it's just a side effect with no specific purpose.

Either way both parents physiologically respond to the birth of a child equally (both also have higher levels of corisole after which increases levels of stress which some suggest is there to make them more concerned for the well being of their child), putting aside the notion that men are not fit for child rearing; if anything the research indicates that ancient men who stuck around to help with the kids instead of hunting and fighting would have been doing their progeny a greater service in both the short and long term.