Alien Binary Genders/Sex

I had a post pop up on my dash recently lamenting the fact that aliens in a certain video game all conformed to the familiar human male/female arrangement, arguing that it is unlikely that such an arrangement would evolve on a completely different planet. Well, I don’t think it’s that unlikely to have the coevolution of ova and sperm, thus being able to define male and female, however the phenotypes are less likely to be the classic male and female that we recognize as mainstream human.

I will also tend to refer to male and female as sexes rather than gender, as I am talking about genetic and phenotypic differences and not how these species identify or perceive themselves in a society.

Please note I am making the following assumptions about these hypothetical, fictional, alien species.

  •  We are talking about physical beings made of molecules, no energy or light based aliens.
  • These aliens are also made of an arrangement of cells
  • These aliens have some method of genetic information storage, whether it be DNA or an alternative molecule that can replicate and be transmitted, thus allowing evolution to occur. Non-evolved species (eg those artificially created) may completely lack any method of genetic transfer and thus have no need for any sexes.
  • I refer to many of these hypothetical alien species as ‘animals’, meaning they are multi-cellular heterotrophs (they have to eat something for nutrition) and generally ambulatory, it is not a generalization about appearance or sentience.

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