I wanted to respond to your question because while I don't know very much about this particular subject myself, I did have the pleasure of attending a talk by Robert Martin, author of How We Do It ( In the talk and in his book he does address this topic (and the book Sperm Wars) and basically says that while it was a highly influential idea, the underlying science isn't reliable. He argues that evidence suggests that humans have not evolved under multi-male types of mating systems. There is a lot of evidence to back this up, and revoke the idea of "killer sperms." Check it out and see what you think! If anything it is an interesting read.