I've actually read more details about this. Apparently, it comes from studies of Y-chromosome DNA and mitochondrial DNA that indicate that the female common ancestor of all living humans is a lot older than the male common ancestor of all living humans. However, this past year, researchers discovered a man with a Y-chromosome that threw off the timeline drastically - which throws the conclusion of sex-based differential reproduction into question.
Yes, the common ancestor is sensitive to single observations. It is idiotic to base conclusions on such non-robust statistics, and indeed, Wilder et al do not.
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.