OK cool, yea, I got that point, just was a bit confused about the context of homo erectus. I agree, though. It seems biologically, primates just generally aren't super-breeders.

IIRC, earlier homonids probably came to breeding age quicker than we do (under depending on nutrition, etc)., so a Homo erectus female of 10 years may have already been in prime mothering age. A child every 2-3 years or so would mean that by age 30, she'd possibly be a grandmother and done with most child rearing.

I do agree as well that mortality rates are on average overblown... once they pass the first two or so tough years, their odds are much improved