> It’s probably unnatural for adult men to spend much time with tiny children in the first place.

Sorry, what? The framing of this sentence alone has a very creepy vibe. I can't speak for all of us, but most us have strong protective instincts towards kids of all ages, especially the youngest ones.

> This is why many men find it difficult, it is contrary to instinct.

Contrary to whose instinct? If I had a kid, I would want to ensure his/her safety and success. Men in general yearn for it. And there's nothing that suggests men are incapable of it. Research indicates good outcomes. And I know fathers who are the sole care givers for young kids when life makes it inconvenient for the mother.

> Do hunter gatherers split care of tiny children? Whatever they do is what we’re wired for, mostly.

Hunter gatherer culture is at least ten thousand years old - plenty of time for social behavior to evolve. Modern humans, including men are very heavily invested in kids because humans can't have a lot of kids. Ensuring each one's safety becomes important.

Heck! Humans, including males are very nurturing and protective towards even children of other men and other species. Plenty of evidence that your assertion doesn't hold at all.