Trigender Biology Inquiry

Substantial postings about constructed languages and constructed worlds in general. Good place to mention your own or evaluate someone else's. Put quick questions in C&C Quickies instead.
Astraios
Sumerul
Sumerul
Posts: 2974
Joined: Fri Mar 05, 2010 2:38 am
Location: Israel

Re: Trigender Biology Inquiry

Post by Astraios »

I haven’t abandoned this discussion, it’s pretty fun speculation.


Like the ruffs I mentioned, incubatorhood could be a relatively rare polymorphy, or it could just be a result of differently nourishing any ordinary infant, which would otherwise grow into a normal adult, like in ants and bees. I don’t think it at all unlikely that an incubator caste could exist; as for the polymorphy, it’s probably more complicated to figure out how it was selected for. In ruffs, the rarer satellite and faeder actually attract more females to a territorial male’s lek, and females prefer to mate with them than with ‘regular’ males, so the polymorphisms are continuously selected for, despite being rare, and the territorial males tolerate the presence of satellites and faeders in their leks. As the variation is unrelated to chromosomal sex, female ruffs can also be S- and F-type, as well as ‘regular’, but in them it doesn’t manifest as any meaningful behavioral or morphological difference. Perhaps incubatorhood in your conspecies is a rare autosomal ‘condition’, which only manifests in certain individuals in the absence of another incubator (such as when the old one dies, or when a new colony is established). I don’t know how such a morph would be selected for in the early stages before separate incubation became the only means of reproduction, but I’m sure a description of the process could be contrived.


Assuming that ovulation happens at any time, perhaps induced by orgasm (hey, a use for the clitoris), rather than during a brief mating season; that some social behaviors already exist, such as pair-bonding; and that young are fed on some tasty product of the mother’s own making, like unfertilized eggs in some frogs, or royal jelly in ants, or poop in koalas (... let’s just call it ‘milk’, though I’m not under the impression we’re talking about a mammalian conspecies here), one might posit the following line of development for an incubator-caste from the distant past to the contemporary conspecies:

Shorter gestation periods are selected for in early stages, in order to maximize the number of offspring each breeding pair can have over their lifetime. A larger brood of helpless young implies an increase in altruistic social behaviors, such as older siblings babysitting for breeding pairs. As social living becomes more pronounced, so too does the specialization of certain tasks, including babysitting. The females most able to provide milk become the best candidates for nursemaid; in order to produce milk, they need to be well-nourished themselves, which leads to a novel altruistic behavior: feeding the babysitters, who can’t leave the nest to forage/hunt. With only one mouth to feed, the breeding pairs and the other members of their group can cooperate primarily to feed the babysitters, and to only secondarily care for their young, which are now fed exclusively by the babysitters.

Millions of years go by, and gestation is further shortened; now premature fetuses are born and carried on the babysitter’s oversized body, perhaps in a pouch or fold of skin next to the abundant milk glands. Cooperative living is really taking off, and several breeding pairs may share a territory containing a single nest and babysitter, bringing her food and protecting her from danger. Babysitters are selected at birth from a brood by size, and overfed a particular diet to induce them to change (like queen bees). Orgasm-induced ovulation has developed further; now, once the presence of a zygote has been ‘registered’ in a female’s body, repeated orgasm will trigger birth (or egglaying), and the clitoris has lengthened into a sort of erectile pseudopenis, which makes transferral of young easier and less haphazard; perhaps the fetus crawls from the vagina up the clitoris seeking the babysitter’s milk glands. Males continue to mate with ordinary females to inseminate them (they have always dispreferred directly mating with babysitters, for whatever reason), but females now regularly ‘mate’ with babysitters to induce orgasm/birth, and hand over their offspring.

Millions more, and the babysitter has turned into a totally sessile surrogate incubator-caste. Its pouch has become a huge internal pseudowomb, and its milk glands have become a sort of giant placenta which nourishes the growing fetuses, and allows them to develop internally for longer, leading to more complex brains, and the delivery of more highly developed young. The womb of ordinary females has become almost totally useless; orgasm now triggers ovulation and birth spasms simultaneously, whether the female is pregnant or not. The marsupioid crawling-fetus strategy has also become defunct, as gestation has become too short to allow the fetus to develop limbs before being passed into the incubator. Females expel tiny eggs from the vagina shortly after fertilization, and the pseudopenis has become dextrous to aid in their transferral; the entrance to the incubator’s pseudowomb is a small orifice which the pseudopenis penetrates, depositing the eggs inside (or perhaps the pseudopenis is now a specialized birth canal, and fertilized eggs are ejaculated straight through it into the pseudowomb). The largest female embryo will develop in utero into the next incubator, while the rest become ordinary females.


Of course, there is always the option that the incubator actually isn’t even a member of the same species as the males and females. It could have evolved from a mutually beneficial relationship between two animals, like farming ants whose fungus is unique to their farms. Your conspecies ‘farms’ the sessile incubators, and the incubators nourish your conspecies’ young in return. Perhaps this evolved from wasp-like parasitism; the incubators’ ancestors were already sessile, and got sick of being eaten by voracious fetuses, and developed a specialized internal compartment to host the parasitic species’ young; this process would be an anti-predator adaptation parallel to, say, autotomy in lizards or crabs, who sacrifice bodyparts in order to avoid being completely eaten. After millions of years of joint evolution, this becomes the mutually beneficial relationship we see in your conspecies. This would obviously entail development of the female’s genitals already from a true ovipositor, which I don’t see why couldn’t have evolved itself from a repurposed other part of the anatomy.


As for the semi-external fertilization, I don’t have enough time (or coffee) right now, but there is a genus of booklice (Neotrogla) whose females have a gynosome, which is intromitted into males in order to actively extract from them a packet of seminal fluid and nutrients. It doesn’t sound so huge a step from something similar to that, to everting a clutch of eggs for fertilization by an externally delivered spermatophore, and retiring it back into the body for internal gestation. Seahorses might also be mentioned; during I guess “inovulation” of the male by the female, the pouch is opened to the ambient for a few seconds while she deposits her eggs, which are fertilized immediately, and sealed as the eggs develop; that gives you a very short technically-external fertilization, in a seawater-filled chamber, followed by internal gestation.

User avatar
Salmoneus
Sanno
Sanno
Posts: 3197
Joined: Thu Jan 15, 2004 5:00 pm
Location: One of the dark places of the world

Re: Trigender Biology Inquiry

Post by Salmoneus »

*slaps forehead*
Oh, of course, they develop from nursemaids. Obvious when you say it. Not sure about the precise details, but yeah, that's basically how it originates.


In other news: kudos for "perhaps the fetus crawls from the vagina up the clitoris seeking the babysitter’s milk glands" - one of the most distinctive sentences I've seen in a while, I think.... no doubt someone is furiously scrawling some rule 34 as we speak...
Blog: [url]http://vacuouswastrel.wordpress.com/[/url]

But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!

User avatar
KathTheDragon
Smeric
Smeric
Posts: 2139
Joined: Thu Apr 25, 2013 4:48 am
Location: Brittania

Re: Trigender Biology Inquiry

Post by KathTheDragon »

Isn't that basically what kangaroos, do? That last bit.

chikiko
Niš
Niš
Posts: 1
Joined: Sat Oct 01, 2016 5:09 pm

Re: Trigender Biology Inquiry

Post by chikiko »

It seems to for a race to be trigendered there would be a need for it. If female can carry their own young there would be no need for this 3rd incubator gender. As such the most logical conclusion would be that the incubator gender/sex would be the only one to carry a uterus. On our world you could say that female mammals do double duty. they have ovaries to form eggs, and they have a uterus to gestate the baby. But it doesn't have to work this way. While seahorses don't reproduce the way we do, it would be possible to have seahorse like reproduction in mammals, where the female gives the male her eggs and he then fertilizes it within him and then gestates the baby. So therefore if the uterus doesn't need to be either the egg producer or the sperm producer, there isn't any reason that the role be given to an independent 3rd gender/sex. In this way incubators are essential to race an not merely a genetic accident like intersex and turner's in humans. Marriage to this species might be triune where all three would form a single family unit.

Genetics would be complicated compared to us. But there are already several complicated sex determining systems in the real world. Fruit flys determine sex by the ratio of their X chromosomes to their autosomes. While they also have Ys the Y chromosome doesn't determine sex only the ratio of Xs to autosomes. So there is no reason that this species could have an odd sex determing system as well.

Post Reply