Worldbuilding with Parthenogenesis

Along with artificial wombs and other new and futuristic reproductive technologies, cloning is a staple of science fiction, but for all the fantastical examples, we too often neglect that cloning already exists in nature: it’s called “parthenogenesis”, and it expands the universe of possibilities for worldbuilders.

We often associate sexual reproduction with the higher life-forms, and while this is largely true, there are plenty of complex life-forms that can reproduce asexually, who need no sperm to fertilize their eggs in order for them to grow and develop; this is called parthenogenesis, and it can produce offspring genetically identical to the mother, i.e clones.

The curious Dominance of sexual Reproduction

Since this requires no male to mate with and reproduces all instead of only part of one’s genes, one might think asexual reproduction would be dominant, but it seems combining genes from two individuals is much more effective than just copying one’s own genes, either directly in the case of cloning or less-directly in the case of “automixis”, where genes from the same individual are recombined and thus result in offspring of a different genotype (there still is no source of truly new genes, though).

This process of combination often associated with sexual reproduction, but hermaphroditical reproduction, where members of a species each have both sex organs and don’t really have sexes like we do, produces the most genetic diversity and the easiest mating process, yet the two-sex system dominates among the most complex life-forms, despite having a whole class of the species taking up resources that only diversifies the genes and can’t reproduce (namely the males).

Obviously there must have been some evolutionary advantage to this arrangement, most likely, as suggested by Geodakyan’s evolutionary theory of sex, that it is more effective to have one sex devoted to developing new traits (males) and another sex devoted to conserving good traits (females). If this is true we should expect males to vary more in their traits than females, and across a shockingly wide range of traits across a wide range of species, including humans, that’s exactly what we do see.

Such fundamental factors driving the evolution of sex suggests to me that the two-sex system might be common among complex Earth-like life in the cosmos. Perhaps not universal, though; snails and slugs, for example, tend to be hermaphrodites, and hermaphroditism is the norm among plants.

All-Female Races of Clones

Much more interesting are the species that can only reproduce by parthenogenesis, as a result of some evolutionary pathway or through interspecies hybridization. The New Mexico whiptail lizard is a product of interspecies mating, like the mule, and cannot produce viable offspring sexually; it can, however, reproduce parthenogenetically, and thus are an all-female species who bear clones.

The coolness doesn’t even stop there; they require sexual stimulation to produce a clone, and this has to be provided by another female New Mexico whiptail, hence their popular moniker of “lesbian lizards”. In some other species parthenogenesis is induced by the presence of sperm but the sperm doesn’t actually fertilize the egg. And of course in yet others the clone can be produced all alone.

Natural Cloning for Science Fiction Worlds

Any good science-fiction worldbuilder should already be thinking about the possibilities for alien races who can or must reproduce in this fashion, not to mention genetically engineering such an ability within humans, making the famous lesbian-separatist feminist communes, not to mention small groups of castaways, into indefinitely sustainable populations even without resort to artificial reproductive technologies. Natural cloning might also be desirable for generation ships, as it means less variation from the founding population’s genotype, and less potential for nasty surprises like subsequent generations rebelling against the original mission.

Women who have exceptional traits they would like to preserve in their offspring would likely find parthenogenesis a far better bet than sexual reproduction, which tends to dilute traits that deviate from the mean of the offspring’s bloodlines. Sure, this could be done artificially, but being able to do it “naturally” seems like a more elegant and less crude solution.

It’s worth noting that while a species that uses the XY sex-determination system, such as humans, can only bear female offspring parthenogenetically, as there is no source for a Y chromosome (females are XX), that is not a universal limitation even on Earth. In species that use the ZW sex-determination system, for example, males are ZZ and females are ZW; therefore females can provide both male and female chromosomes to offspring, permitting the production of sons that are clones of the mother except for their sex. Automixis, of course, additionally permits offspring that have no new genes but are not clones.

Natural Cloning: not just for Females!

Although not exactly the same thing, it’s worth noting that in central and South American electric ants, whose queens reproduce both parthenogenetically and sexually, it’s common for eggs fertilized by males to lose the female contribution and develop as clones of their father, enabling males to create clones too, though unlike the females they require another fellow creature to do it with. According to Wikipedia this nigh-unique ability gives these ants the benefits of both sexual and asexual reproduction! Yikes.

Anyway, a big implication for science-fiction and fantasy worldbuilders alike is that just because a race is complex doesn’t mean it must reproduce sexually. Orcs in fantasy are often depicted as reproducing in various bizarre fashions: why not parthenogenesis? They could all be one sex, female, and not having mates would help them devote more time to fighting, as well as make them more alien. A lack of individuality might be explained by large numbers of them being genetically identical. It would seem to make sense.

The Mirage of Artificial Wombs

In science fiction artificial wombs are often employed as the one true futuristic method of reproduction, but they have the critical disadvantage of the baby not feeling its mother’s heartbeat and not hearing its mother’s voice, among other deficiencies when one only has the cold comfort of a machine, so I suspect artificial wombs will realistically only breed an inferior race, at least among humans.

Human development depends on the bond with one’s mother; from conception to over a year after birth, from being in the womb to breastfeeding, mother and baby are linked as one, and severing that link can’t possibly lead to anything good for either mother or baby. We already know adoption doesn’t and baby formula doesn’t, and neither of those is anywhere near as drastic a deprivation as an artificial womb.

No, I suspect, barring any dystopian developments, the norm will always be for human mothers to bear and nurse their own children, especially considering the likelihood of genetically engineering away the maladies of pregnancy and turning the pains of childbirth into pleasures. In a world like that girls would be lining up to get pregnant!

Considering Jango Fett

If artificial wombs are forbidden that has interesting implications for clone armies a la Star Wars. In such a world Jango Fett could have embryos with his and only his genes artificially implanted into a suitable number of surrogate mothers, but much more interesting is the idea of the male contribution overriding the female’s and leading to the woman bearing a clone of the father a la the electric ants; most likely the human women would need to be genetically engineered to have this ability. This leads to the decidedly sexier possibility that our Jango would be able to impregnate the surrogate mothers the old-fashioned way. In the future it should be easy to carry out any desired genetic alterations in utero.

An even more intriguing possibility would be for Jango Fett to be a woman, reproducing parthenogenetically into a clone army of descendants, again with the desired alterations carried out in utero. The drawback is that this takes much longer, since instead of an arbitrarily large number we’re starting with just one woman. Even if she bears twins every 9 months, by the earliest time a granddaughter could be realistically be expected, 14 years, we only have 38 clone daughters. At the same rate, though, 38x every 14 years, we end up with 1,444 clones after 28 years, 54,872 after 42 years, and 2,085,136 after 56 years.

The last figure might make for a good-sized army, but there really would have to be a “Grand Plan” on the part of the Sith to wait that long! Exponential growth is a beast, though; after 70 years there are 79,235,168 clones, and after 84 years over 3 billion! Taking the 7000:1 ratio between the US military and the world population as a rough indication, an army of 3 billion could achieve hegemony over a population in excess of 2 trillion, which is in the lower end of the classic space-opera range!

For obligate parthenogenetic species, the whole species will be made up of various types that are clone lineages or (if automixis is employed) more individualized genotypes that nevertheless inherit all their material from their mothers, with each lineage’s only natural source of new genes being mutations.

More Out-There Ideas of Parthenogenesis

The Asari from “Mass Effect” are aliens with an interesting take on parthenogenesis of the (I think) automictic variety; they require a telepathic link with a partner to reproduce, and the memories, thoughts and feelings of the partner determine how half of the offspring’s genes are altered. A little out there but I kinda like the idea.

Genetic Engineering through the Human Body?

An even more out-there idea would be for the faculties of genetic engineering to be present within a human or alien body, with perhaps whole organs dedicated to creating new genes and testing them, a “mutation factory”, and if they prove to be successful mutations incorporating these new genes into parthenogenetic offspring. Conscious control of this process might be theoretically possible. Now that would be interesting!

I might incorporate that into my far-future space-opera setting, though perhaps further in the future than the 31st to 33rd century period my (so far) two stories set there take place in. So far in terms of what I’ve depicted there definitely are modifications in the areas of fertility and infertility, communal inclinations, physical appearance, libido, orgasms, intellect, pain and pleasure in childbirth, bonding a la bird-style imprinting between mates, and the immune system, but none of that is as drastic as a fully-functional internal genetic-engineering laboratory!

Well, maybe the biological nuclear fusion reactor the Sisters of Mokosh use for their initiations is, but that’s not within a human, and in any case I have to save some of the ideas I have of future technology for later eras!

A parthenogenetic Sisterhood of Mad Scientists

Parthenogenesis in humans, though, seems like the kind of thing that would fit in well in the “Warp Dawn” era. The Sisters of Mokosh might have the back-to-nature ethos that compels them to keep men around in a subordinate role as husbands and fathers of their children, but an interesting foil for them might be a sisterhood, pagan space nuns basically, that has a desire to separate themselves from men completely and a much more mad-scientist orientation.

I envision such a group genetically engineering themselves to be obligately parthenogenetic and being very selective in their membership, becoming a group comprised of clone lineages of the smartest, prettiest, and meanest woman scientists of the cosmos; when a woman is selected she bears an appropriately genetically-engineered clone daughter, who is the one, along with her clone descendants, admitted into the secretive inner circle of this group.

I’m thinking that as a counterpoint to the very communal orientation of the Sisters of Mokosh, these sisters (the Sisters of Saga? of Isis?) might have a very individual orientation, usually living, working, studying, and experimenting alone (favoring ocean planets with isolated islands), only gathering with the others during holidays, somewhat like a cross between festivals and scientific conferences, that are weeklong and take place a few times per year, perhaps connected to the solstices and equinoxes.

The “lesbian lizard” style of parthenogenetic reproduction, where it’s triggered by sexual stimulation from another member of the race, is kind of interesting, but I don’t think these sisters would go for a system that makes any one of their members dependent on anyone else. Rather, I envision a much cooler version where the woman going into a deep meditative trance for days (weeks? longer?) on end, essentially triggering reproduction by willpower.

Indeed, parthenogenesis opens up an infinite number of avenues for reproduction without sex or even sexual stimulation; since no actual exchange of genetic material is required the stimulus for childbearing could well be almost anything.


In any case there are definitely more things in heaven and earth than are dreamt of in the most popular tropes for what futuristic or fantastical reproduction must look like. Parthenogenesis, especially of the clonal variety, is so cool it will definitely make appearances in my worldbuilding and my stories in the future, for both human and (especially) alien species.

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