"In contrast to demographic reconstructions based on mtDNA, we infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky. We hypothesize that this bottleneck is caused by cultural changes affecting variance of reproductive success among males."

Saying that the average man reproduces less than the average woman seems to fit the facts as presented in the paper. I've not read other papers that may refute that one though. This is not my area of expertise.