>Humans have less sexual dimorphism than the other great apes

Compared to H. Erectus, it's dramatic... at least until 2020. I see I'm behind the times.

>they weren't larger than modern humans

Where am I getting my science these days, smh...

>This is not a realistic birth spacing

It's not. I was unclear, I see. This is the average length of time between one birth and the conception of the next. Humans are physically capable of getting pregnant immediately after birth but unlikely to do so for roughly six months. Add in the six months it takes for the average length of time for conception and you've got a year. This was looking at the maximum number possible, rather than what's probable, because everything is pure speculation anyway.