Human males are also believed to block gene Igf2 in human females (De Sousa, Rosalind Institute, Scotland). Males block parthenogenesis in order to make females make males. (Trust will explore parthenogenesis and the origin of maleness in the next set of posts). Males are genetic parasites, possibly having originated as parasitic DNA or an infectious genetic virus (noted by French biologist Claude Combes in Parasitism: The Ecology and Evolution of Intimate Interactions), or later, simply by mutation (see geneticists Sykes, Jones or Graves). Maleness appears to have evolved on Earth independently at least three times (but probably many many more, and most likely in different ways), yet maleness as a biological strategy is the same: intercept females’ power of generation and harness that power to perpetuate yourself. Parthenogenesis – life without males – was once the norm (and for some species, still is). Mammalian females, though blocked, though now incapable of successful parthenogenesis, have not yet lost this genetic relic.