Right. That's why I also looked up the indigenous people of New Zealand, who were hunter-gatherers until pretty recently. And who still had monogamy as the norm, except for the chiefs, who had ~1 concubine. If you think that other hunter-gatherer societies (preferably close to ancestral population densities) would be different, then how about you do the research :P
There's an idea I've seen a number of times that 80% of women have had descendants, but only 40% of men. A little research tracked it back to this, but the speech doesn't have a cite and I haven't found a source.
The reproduction rates for men and women (possibly for the whole history of the species) seems like the sort of thing which could be found out, but I'd like more solid information.