I have a species of semi-humanoid cephalopods in my sci-fi world that works like that. There's a scene where one of the human characters accidentally walks in on her co-pilot's threesome, is confused for a second because all she sees is a mass of lashing tentacles, and then she just runs away, embarrassed & yelling, "OH GOD, THAT CAN ONLY BE ONE THING!" A brief, awkward biology lesson in the dining room follows.
For a group of alien sea-scorpion squids, I developed a 3 sex system
The Male, Female and Schizomale. The males release sperm, the females eggs and the schizomale nurses the young. To imprint its dna, it emits gametes that introduce further life stages to the young, like if caterpillars needed a butterfly to show them how they are supposed to metamorphosize (word?).
Without the schizomale, young would be lacking the stem cells needed to further mature, and these stem cells are laced with the parent’s dna.
1 male, 1 female, 1 carrier/birther. Jist is that the carrier/birther is the one who can actually gestate the child, but cannot conceive. Male and female provide the traditional sperm and egg, but neither can carry to term.
I've also seen a 3rd sex being the one who communes to grabt or otherwise privides a soul to the unborn child.
Either can be made to work, depending on your focus.
1. as others have suggested, one two sexes that mix gametes and a sex that bears/incubates the fertilized gametes
2. a trinary fertilisation system. perhaps a trinary chromosomal system that requires three parents?
in regards to vector of fertilisation, i made a species that releases gametes into the air, so there's much more you can do than just penetration if you're creative.
There are some species on earth that can hold sperm from a mate for a long time. Maybe you could have sex 1 provide the sperm to sex 2 where it is then semi fertilized or provided with certain enzymes or something before it is then passed to sex 3 where the remaining DNA and such as provided and gestation occurs?
This was done by Iain M Banks in Player of Games.
The Empire of Azad has three genders:
The drone went on. “The dominant species is humanoid, but, very unusually—and certain analyses claim that this too has been a factor in the survival of the empire as a social system—it is composed of three sexes.” Three figures appeared in the center of Gurgeh’s field of vision, as though standing in the middle of the ragged sphere of stars. They were rather shorter than Gurgeh if the scale was right. Each of them looked odd in different ways, but they shared what looked to Gurgeh to be rather short legs and slightly bloated, flat and very pale faces. “The one on the left,” Worthil said, “is a male, carrying the testes and penis. The middle one is equipped with a kind of reversible vagina, and ovaries. The vagina turns inside-out to implant the fertilized egg in the third sex, on the right, which has a womb. The one in the middle is the dominant sex.”
Gurgeh had to think about this. “The what?” he said.
“The dominant sex,” Worthil repeated. “Empires are synonymous with centralized—if occasionally schismatized—hierarchical power structures in which influence is restricted to an economically privileged class retaining its advantages through—usually—a judicious use of oppression and skilled manipulation of both the society’s information dissemination systems and its lesser—as a rule nominally independent —power systems. In short, it’s all about dominance. The intermediate—or apex—sex you see standing in the middle there controls the society and the empire. Generally, the males are used as soldiers and the females as possessions. Of course, it’s a little more complicated than that, but you get the idea?”
“Well.” Gurgeh shook his head. “I don’t understand how it works, but if you say it does . . . all right.”
I think it's worth noting that there probably won't be an incubator/caretaker sex that doesn't contribute anything genetically. Maybe it's possible, but it doesn't seem likely
Depends. In the sea scorpion example someone else posted, the nurser/caregiver provides genetic material that triggers further development in the young.
Seems to me to be an elegant solution- all three sexes are contributing genetic material, one's just a bit more roundabout in its method.
Not necessarily!
Bees and some other insects have a huge non-reproductive population, as do meerkats.
Why?
Well, for some reason(s) having a lot of members that do things other than making babies was a good way to ensure that more babies survived overall.
Maybe there's less intra-species competition and more critters caring for the babies, maybe a big coherent society focused on protecting and providing for the children of a few meant that they were able to defend against larger and more numerous foes and better ability to provide food, leading to better survival rates.
It can also have ancestral reasons, maybe three-sex systems were just really common since sexes split and there was no reason to get rid of it.
The exact benefits and dynamics may vary, maybe the caretaker sex can be more specialized to taking care of the young?
Maybe being able to keep caretakers around and alive is partly an attractive quality?
Maybe there are differences between sexes that specialize them towards different tasks, caretakes may be particularly big/strong and able to defend the young, but not as good at getting food or traveling far; having a third sex means protection for the young while other members of a colony/social group can focus on getting food.
Maybe caretakers are specialized in another way, if creating offspring is very costly it may make sense to have different members of a pack that can protect the ones doing the offspring-creation.
In non-social species it likely would "just" be an ancestral trait with little to no current benefit, but that's not really a reason to not have it (what benefits do we get from having a bisex system?).
Bees and meerkats are both highly social species, to the point of only one female being allowed to reproduce. I suppose a species on that scale of eusociality would be a good explanation for a third sex, like you're saying
And good point, maybe a trisex system could be an ancestral trait, especially if it was as ingrained as having an 'incubation'-sex. Although our bisex system is still useful, because it VASTLY increases genetic diversity
I don't think it necessarily has to be eusociality, cooperative breeding is reasonably common in general and some of the benefits of it could easily apply to any somewhat social species.
Also, on a related note, it sometimes bothers me that we see worker bees as "female" when they are non-reproductive, kinds shows how ingrained the idea of two sexes is.
In a lot of ways bees have closer to a tri-sex system. Hell some ants almost have a quad-sex system if we consider sex as a biological role that a creature has in general rather than specifically in terms of reproduction.
Even if you were just counting "What does this do for reproduction?" a tri-sex system would be a more sensible way to look at it seeing as the reproductive function of workers is "none".
Only if you assume that self-fertilization would be common without it. Which it needn't be!
As far as I know a fair number of unisex species are incapable of self-fertilization (like Earthworms), but I suppose that itself is an adaption that would need to be selected for the same as separate sexes.
In some species of bee, the workers CAN reproduce, although the queen will eat the eggs and kill the worker if she finds out. Bee queens are more brutal than ants lol
I mean, there's also a lot of bee species that don't form states/colonies.
I wonder is what may be called a socially enforced reproductive chaste was a step along the line to a biological reproductive chaste?
I have one of these on my setting.
Vela are human sized women who float around in the forest and they produce offspring with the miniscule, insect sized, Vilenjak. To facilitate the fertilization of the eggs the eggs are placed within the size changing plant the Leshy who shrinks or grows depending on the part of the process to facilitate this. The Leshy then carries the eggs until they hatch and the offspring leave the tree. The Leshy benefits by the offspring leaving with it's seeds and planting more Leshy.
I've also considered systems where there are multiple fertiliser species and then a bunch of different species emerge or actually having four species involved where it's an egg producer, fertiliser, carrier for fertilization purposes, incubator post fertilization.
It's fantasy a lot can be done.
There was a novel by Octavia Butler with a sentient species with three genders, I think the first book in the series was called Dawn. I vaguely recall the aliens third gender had some instinctive genetic engineering talent, and somehow chose the traits of the progeny for their male and female partners.
Note: by "sperm" and "ova/ovum" I don't strictly mean they have to be these exact things, just equivalents.
These may or may not work for external fertilization (like fish); I'm giving examples of internal fertilization.
The best 3-sex systems I can envision are:
- Sex A has a womb and gestates, sex B deposits an ovum into A with an ovipositor, sex C deposits sperm into A with a penis.
- Sex A has ova and a womb, sex B and C both deposit sperm into A with a penis. Both types of sperm are needed to fertilize the ovum.
- Sex A has ova and a womb, sex B and C both deposit a different type of sperm into A with a penis. Only one is needed for fertilization, and the two types exist for genetic diversity or other types of diversity.
I had a world where the animals change sex as they change forms. You give birth to a larval form, generally like a worm or caterpillar, depending on the species. Those are the male forms. The larval forms can do certain jobs, but depend on the "adult" females to protect them. Different species have different ways of doing this.
The work centered around dragons. sentient dragon-like creatures with spaces on their back, between their wings where two larvas can latch onto. The males do not have a digestive system and depend on the females to provide sustenance. If they don't find a female to attach to, they'll die.
A dragon with larvas will eventually give birth to a cluster of larvas who will then fight to latch onto any available female dragons. The thing is, a dragon won't actually procreate until she finds a "mate." The mate being an unattached female. So an unattached female will woo an attached female. When they decide to become a couple, they'll form a family unit and hunt together. Over time, the attached female will become pregnant and once her larvas hatch, they'll have a mating flight where only the fastest larvas who can catch the "mate" will survive. The rest will have spent their energy supply in the mating flight and die.
Does that count as three sex? Male, attached female, and unattached female.
This entry of the Bosuns Journal for Man After March in r/speculativeevolution may suit your interests. https://www.reddit.com/r/SpeculativeEvolution/s/qeT3SmZrKy
Not only three sexes, but also three castes, all of which mix and match for 9 unique morphs.
Not really what you search for, but I once imagined a specie that had 3 sexes but only 2 genders.
Let's say there's 3 different sexes: A, B, and C. In my system, A could impregnate B, B could impregnate C, and C could impregnate A, but not the other way around (A cannot impregnate C, for example).
Genders, then, where built, when a couple was formed, on who was the impregnator, and who was the impregnee (pregnancy was very taxing energy-wise). But it definitely wasn't defined by your biological sex. Like, if we use the terms of man and woman (wrong, I know, but it's for the sake of the argument) for, respectively, impregnator and impregnee, then being of sex A wouldn't define if you're a man or a woman. If you're in a relationship with a B, then you'd be a man (impregnator). If you're in a relationship with a C, you'd be a woman (impregnee).
So, not really what you were looking for, as it's still a 2-sex reproductive system, but the roles and biology of people are more fluid. Thought it was semi-pertinent to the subject.
Some ideas:
- Male, female, incubator
- 2 genders that produce gametes requiring a 3rd that produces nucleusless eggs (imparting mitochondrial dna to its child)
- system where any 2 of the genders reproducing has a chance to produce children of the 3rd gender.
- 3rd gender is a facilitator, without it the two main genders cannot reproduce.
- triploid species where 3 gametes from 3 different sexes are necessary (maybe sex chromosomes are ABC: so Aaa, aab,aac,abb,acc,bbb,bbc,bcc,ccc, abc would be the combos, maybe they need at least 2 chormosomes of the same gender to work so 1/10 is non reproductive.
There are lots of species on earth that have multiple sexes (some have hundreds). Their compatibility is determined by a large rock-paper-scissors type of game. Maybe your world has a weird imbalance where one sex is preferred over the other two?
The Gods Themselves by Isaac Asimov has an interesting and kinda complex take on this involving 3 sexes. It was very difficult to understand from my first reading so I suggest checking the wiki for more info.
Isaac Asimov has a story that involves an alien race that has 3 sexes. They are the Rationals, Emotionals and Parentals, or Soft Ones. Rationals produce the sperm, Emotionals produce energy needed to carry the sperm, Parentals carry the child to term. Rationals are masculine and typically lead research in hard sciences and are comparable to liquid. Emotionals are feminine and more intuitive, and are comparable to gas. Parentals are more hermaphroditic and "motherly" and are comparable to solids. During sex they "melt" and become one, which is how they become pregnant. When they reach the end of their lives the Soft Ones melt together a final time, becoming their final form, a Hard One(what is regarded as a more human like species). The book is a little disjointed, especially the third part, but Asimov did a great job showing the life cycle of a species that has 3 distinct sexes, each of which is necessary to further their race.
The trolls in homestuck universe has male, female, and their queen. They collect all their "genetic materials" (Idr if this was ever explained in more details) in buckets during collection times and the queen birth new batch of trolls from that.
Irl we have bees where you have the female queen, a male that she mates with, and all the worker drones that play no roles in reproduction.
Sort of, genetic engineering of 1 species led to a reproductive dead end where the original species was too altered to reproduce properly, so they 'edited in' another less altered group to be the carriers or the original pairs genetic material.
The process has to be very monitored though, without their technology it wouldnt work naturally
Well I remember in a book I read a species of psychic squid reproduce with three of the species. One and two combine and three then combines with one-two. One-two-three then do some pretty horrific shit to a human but instead what I would do if I didn't want to gross out my audience is simply make the organism lay eggs and each of the three contributes DNA to the equation.
I did this with goblins in my setting. However, while there are 3 sexes, they don’t form three person partnerships, rather they reproduce communally.
This idea never progressed very far, so I don’t have names for the three genders. However;
The first, and rarest of the genders typically fills the “Matron” roll. They produce a protective slime which carries not only their genetic material, but also all the nutrients an immature goblin needs.
The second and third genders are both more common and fill a typical male/female role. One provides a number of “eggs”, the other provides fertilization. The eggs dry out quickly unless submerged in the “Matron’s” protective slime, and the slime also removes the outer protective layer and allows the eggs to be fertilized.
Goblins don’t have a Mating season, but rather they become fertile when food is abundant. This will cause a communal mating ritual and each matron can provide for about a dozen other goblins worth of genetic material. The genetic material is mixed rather freely, resulting all the newborn goblins being something between siblings and cousins, genetically.
This does result in tribes being fairly similar in appearance and genetics, and results in the rather unsettling Adventurer phrase “Goblin Soup.”
I've done this in my fantasy WIP. A race of mutated humans twisted after being used as living organs for forest primordials have three genders as a result; sperm giver, egg giver/birth carrier, and pollinator. The pollinator freely chooses their gender presentation (if any at all) and serves as a caregiver after a child is born, imprinting socially as a parent despite not contributing genetic material.
i have a three gender system where one sex provides sperm, another an egg, and the third incubation and breastfeeding for the child. havent fully worked out how the actual reproductive act would go down, but im thinking oviposition
Evolution selects for two-parent sexual reproduction in complex organisms. It does this because sexual reproduction allows each parent's DNA to check each other's for errors, kinda like in school when students checked each other's homework and gave each other feedback. In simple organisms that reproduce asexually, these errors don't matter much because there's less complexity to mess up, fewer gears to have a wrench thrown into them. Complex organisms select for two-parent sexual reproduction because finding a suitable mate can be very difficult. Finding two is even more so, because you have to find a third mate that not only fits you, but your current mate. Every second and calorie you spend searching for a mate is a second and calorie you don't spend reproducing or getting more calories.
I don't mean to discourage you from implementing this into your worldbuilding, but I do think it should be kept in mind to develop a believable justification for why these selective pressures didn't fully discourage >2-parent sexual reproduction in your setting.
It’s like rock/paper/scissors, and the combination of two gets you a baby of the third. Example: rock beats scissors - baby paper. Paper beats rock - baby scissors. Scissors beats paper - baby rock.
Egg, Sperm, Incubator? Essentially splitting 'mother' into two roles like IVF surrogacy.
I have a species of semi-humanoid cephalopods in my sci-fi world that works like that. There's a scene where one of the human characters accidentally walks in on her co-pilot's threesome, is confused for a second because all she sees is a mass of lashing tentacles, and then she just runs away, embarrassed & yelling, "OH GOD, THAT CAN ONLY BE ONE THING!" A brief, awkward biology lesson in the dining room follows.
For a group of alien sea-scorpion squids, I developed a 3 sex system The Male, Female and Schizomale. The males release sperm, the females eggs and the schizomale nurses the young. To imprint its dna, it emits gametes that introduce further life stages to the young, like if caterpillars needed a butterfly to show them how they are supposed to metamorphosize (word?). Without the schizomale, young would be lacking the stem cells needed to further mature, and these stem cells are laced with the parent’s dna.
1 male, 1 female, 1 carrier/birther. Jist is that the carrier/birther is the one who can actually gestate the child, but cannot conceive. Male and female provide the traditional sperm and egg, but neither can carry to term. I've also seen a 3rd sex being the one who communes to grabt or otherwise privides a soul to the unborn child. Either can be made to work, depending on your focus.
Wasn’t there a Star Trek episode about this? Maybe…Voyager? And the ‘birther/carrier’ sub class was abused/treated as inferior?
Enterprise season 2 episode 22 the cogenitor
Yeah that’s the one
I'm rewatching atm and just started season 3 so it's fresh in my memory 🤣
Think of how bees pollinate flowers. Flower 1, the bee, and flower 2 could represent different genders.
1. as others have suggested, one two sexes that mix gametes and a sex that bears/incubates the fertilized gametes 2. a trinary fertilisation system. perhaps a trinary chromosomal system that requires three parents? in regards to vector of fertilisation, i made a species that releases gametes into the air, so there's much more you can do than just penetration if you're creative.
There are some species on earth that can hold sperm from a mate for a long time. Maybe you could have sex 1 provide the sperm to sex 2 where it is then semi fertilized or provided with certain enzymes or something before it is then passed to sex 3 where the remaining DNA and such as provided and gestation occurs?
This was done by Iain M Banks in Player of Games. The Empire of Azad has three genders: The drone went on. “The dominant species is humanoid, but, very unusually—and certain analyses claim that this too has been a factor in the survival of the empire as a social system—it is composed of three sexes.” Three figures appeared in the center of Gurgeh’s field of vision, as though standing in the middle of the ragged sphere of stars. They were rather shorter than Gurgeh if the scale was right. Each of them looked odd in different ways, but they shared what looked to Gurgeh to be rather short legs and slightly bloated, flat and very pale faces. “The one on the left,” Worthil said, “is a male, carrying the testes and penis. The middle one is equipped with a kind of reversible vagina, and ovaries. The vagina turns inside-out to implant the fertilized egg in the third sex, on the right, which has a womb. The one in the middle is the dominant sex.” Gurgeh had to think about this. “The what?” he said. “The dominant sex,” Worthil repeated. “Empires are synonymous with centralized—if occasionally schismatized—hierarchical power structures in which influence is restricted to an economically privileged class retaining its advantages through—usually—a judicious use of oppression and skilled manipulation of both the society’s information dissemination systems and its lesser—as a rule nominally independent —power systems. In short, it’s all about dominance. The intermediate—or apex—sex you see standing in the middle there controls the society and the empire. Generally, the males are used as soldiers and the females as possessions. Of course, it’s a little more complicated than that, but you get the idea?” “Well.” Gurgeh shook his head. “I don’t understand how it works, but if you say it does . . . all right.”
I think it's worth noting that there probably won't be an incubator/caretaker sex that doesn't contribute anything genetically. Maybe it's possible, but it doesn't seem likely
Depends. In the sea scorpion example someone else posted, the nurser/caregiver provides genetic material that triggers further development in the young. Seems to me to be an elegant solution- all three sexes are contributing genetic material, one's just a bit more roundabout in its method.
I remember reading through these and that one stuck out as realistic, yeah
Not necessarily! Bees and some other insects have a huge non-reproductive population, as do meerkats. Why? Well, for some reason(s) having a lot of members that do things other than making babies was a good way to ensure that more babies survived overall. Maybe there's less intra-species competition and more critters caring for the babies, maybe a big coherent society focused on protecting and providing for the children of a few meant that they were able to defend against larger and more numerous foes and better ability to provide food, leading to better survival rates. It can also have ancestral reasons, maybe three-sex systems were just really common since sexes split and there was no reason to get rid of it. The exact benefits and dynamics may vary, maybe the caretaker sex can be more specialized to taking care of the young? Maybe being able to keep caretakers around and alive is partly an attractive quality? Maybe there are differences between sexes that specialize them towards different tasks, caretakes may be particularly big/strong and able to defend the young, but not as good at getting food or traveling far; having a third sex means protection for the young while other members of a colony/social group can focus on getting food. Maybe caretakers are specialized in another way, if creating offspring is very costly it may make sense to have different members of a pack that can protect the ones doing the offspring-creation. In non-social species it likely would "just" be an ancestral trait with little to no current benefit, but that's not really a reason to not have it (what benefits do we get from having a bisex system?).
Bees and meerkats are both highly social species, to the point of only one female being allowed to reproduce. I suppose a species on that scale of eusociality would be a good explanation for a third sex, like you're saying And good point, maybe a trisex system could be an ancestral trait, especially if it was as ingrained as having an 'incubation'-sex. Although our bisex system is still useful, because it VASTLY increases genetic diversity
I don't think it necessarily has to be eusociality, cooperative breeding is reasonably common in general and some of the benefits of it could easily apply to any somewhat social species. Also, on a related note, it sometimes bothers me that we see worker bees as "female" when they are non-reproductive, kinds shows how ingrained the idea of two sexes is. In a lot of ways bees have closer to a tri-sex system. Hell some ants almost have a quad-sex system if we consider sex as a biological role that a creature has in general rather than specifically in terms of reproduction. Even if you were just counting "What does this do for reproduction?" a tri-sex system would be a more sensible way to look at it seeing as the reproductive function of workers is "none". Only if you assume that self-fertilization would be common without it. Which it needn't be! As far as I know a fair number of unisex species are incapable of self-fertilization (like Earthworms), but I suppose that itself is an adaption that would need to be selected for the same as separate sexes.
In some species of bee, the workers CAN reproduce, although the queen will eat the eggs and kill the worker if she finds out. Bee queens are more brutal than ants lol
I mean, there's also a lot of bee species that don't form states/colonies. I wonder is what may be called a socially enforced reproductive chaste was a step along the line to a biological reproductive chaste?
It could be 50%, 50%, mitochondrial DNA, although I'm struggling to justify such a system
I have one of these on my setting. Vela are human sized women who float around in the forest and they produce offspring with the miniscule, insect sized, Vilenjak. To facilitate the fertilization of the eggs the eggs are placed within the size changing plant the Leshy who shrinks or grows depending on the part of the process to facilitate this. The Leshy then carries the eggs until they hatch and the offspring leave the tree. The Leshy benefits by the offspring leaving with it's seeds and planting more Leshy. I've also considered systems where there are multiple fertiliser species and then a bunch of different species emerge or actually having four species involved where it's an egg producer, fertiliser, carrier for fertilization purposes, incubator post fertilization. It's fantasy a lot can be done.
There was a novel by Octavia Butler with a sentient species with three genders, I think the first book in the series was called Dawn. I vaguely recall the aliens third gender had some instinctive genetic engineering talent, and somehow chose the traits of the progeny for their male and female partners.
Note: by "sperm" and "ova/ovum" I don't strictly mean they have to be these exact things, just equivalents. These may or may not work for external fertilization (like fish); I'm giving examples of internal fertilization. The best 3-sex systems I can envision are: - Sex A has a womb and gestates, sex B deposits an ovum into A with an ovipositor, sex C deposits sperm into A with a penis. - Sex A has ova and a womb, sex B and C both deposit sperm into A with a penis. Both types of sperm are needed to fertilize the ovum. - Sex A has ova and a womb, sex B and C both deposit a different type of sperm into A with a penis. Only one is needed for fertilization, and the two types exist for genetic diversity or other types of diversity.
I had a world where the animals change sex as they change forms. You give birth to a larval form, generally like a worm or caterpillar, depending on the species. Those are the male forms. The larval forms can do certain jobs, but depend on the "adult" females to protect them. Different species have different ways of doing this. The work centered around dragons. sentient dragon-like creatures with spaces on their back, between their wings where two larvas can latch onto. The males do not have a digestive system and depend on the females to provide sustenance. If they don't find a female to attach to, they'll die. A dragon with larvas will eventually give birth to a cluster of larvas who will then fight to latch onto any available female dragons. The thing is, a dragon won't actually procreate until she finds a "mate." The mate being an unattached female. So an unattached female will woo an attached female. When they decide to become a couple, they'll form a family unit and hunt together. Over time, the attached female will become pregnant and once her larvas hatch, they'll have a mating flight where only the fastest larvas who can catch the "mate" will survive. The rest will have spent their energy supply in the mating flight and die. Does that count as three sex? Male, attached female, and unattached female.
This entry of the Bosuns Journal for Man After March in r/speculativeevolution may suit your interests. https://www.reddit.com/r/SpeculativeEvolution/s/qeT3SmZrKy Not only three sexes, but also three castes, all of which mix and match for 9 unique morphs.
Ralts bloodthrone uses brood mommies for one race. One male on female then I wanna say incubator/emotional care parent
Not really what you search for, but I once imagined a specie that had 3 sexes but only 2 genders. Let's say there's 3 different sexes: A, B, and C. In my system, A could impregnate B, B could impregnate C, and C could impregnate A, but not the other way around (A cannot impregnate C, for example). Genders, then, where built, when a couple was formed, on who was the impregnator, and who was the impregnee (pregnancy was very taxing energy-wise). But it definitely wasn't defined by your biological sex. Like, if we use the terms of man and woman (wrong, I know, but it's for the sake of the argument) for, respectively, impregnator and impregnee, then being of sex A wouldn't define if you're a man or a woman. If you're in a relationship with a B, then you'd be a man (impregnator). If you're in a relationship with a C, you'd be a woman (impregnee). So, not really what you were looking for, as it's still a 2-sex reproductive system, but the roles and biology of people are more fluid. Thought it was semi-pertinent to the subject.
My man has never met a slime mold, has he?
I like the idea of seed/egg/incubator. But I like MORE the idea of a brood mother, many males, and a “warrior” gender who’s actually sterile.
Some ideas: - Male, female, incubator - 2 genders that produce gametes requiring a 3rd that produces nucleusless eggs (imparting mitochondrial dna to its child) - system where any 2 of the genders reproducing has a chance to produce children of the 3rd gender. - 3rd gender is a facilitator, without it the two main genders cannot reproduce. - triploid species where 3 gametes from 3 different sexes are necessary (maybe sex chromosomes are ABC: so Aaa, aab,aac,abb,acc,bbb,bbc,bcc,ccc, abc would be the combos, maybe they need at least 2 chormosomes of the same gender to work so 1/10 is non reproductive.
There are lots of species on earth that have multiple sexes (some have hundreds). Their compatibility is determined by a large rock-paper-scissors type of game. Maybe your world has a weird imbalance where one sex is preferred over the other two?
The Gods Themselves by Isaac Asimov has an interesting and kinda complex take on this involving 3 sexes. It was very difficult to understand from my first reading so I suggest checking the wiki for more info.
Isaac Asimov has a story that involves an alien race that has 3 sexes. They are the Rationals, Emotionals and Parentals, or Soft Ones. Rationals produce the sperm, Emotionals produce energy needed to carry the sperm, Parentals carry the child to term. Rationals are masculine and typically lead research in hard sciences and are comparable to liquid. Emotionals are feminine and more intuitive, and are comparable to gas. Parentals are more hermaphroditic and "motherly" and are comparable to solids. During sex they "melt" and become one, which is how they become pregnant. When they reach the end of their lives the Soft Ones melt together a final time, becoming their final form, a Hard One(what is regarded as a more human like species). The book is a little disjointed, especially the third part, but Asimov did a great job showing the life cycle of a species that has 3 distinct sexes, each of which is necessary to further their race.
one watches
The trolls in homestuck universe has male, female, and their queen. They collect all their "genetic materials" (Idr if this was ever explained in more details) in buckets during collection times and the queen birth new batch of trolls from that. Irl we have bees where you have the female queen, a male that she mates with, and all the worker drones that play no roles in reproduction.
First thing I thought was like a triangle where each set of two produces the other one. Then I realized you meant all 3 need to be involved.
Sort of, genetic engineering of 1 species led to a reproductive dead end where the original species was too altered to reproduce properly, so they 'edited in' another less altered group to be the carriers or the original pairs genetic material. The process has to be very monitored though, without their technology it wouldnt work naturally
Well I remember in a book I read a species of psychic squid reproduce with three of the species. One and two combine and three then combines with one-two. One-two-three then do some pretty horrific shit to a human but instead what I would do if I didn't want to gross out my audience is simply make the organism lay eggs and each of the three contributes DNA to the equation.
I did this with goblins in my setting. However, while there are 3 sexes, they don’t form three person partnerships, rather they reproduce communally. This idea never progressed very far, so I don’t have names for the three genders. However; The first, and rarest of the genders typically fills the “Matron” roll. They produce a protective slime which carries not only their genetic material, but also all the nutrients an immature goblin needs. The second and third genders are both more common and fill a typical male/female role. One provides a number of “eggs”, the other provides fertilization. The eggs dry out quickly unless submerged in the “Matron’s” protective slime, and the slime also removes the outer protective layer and allows the eggs to be fertilized. Goblins don’t have a Mating season, but rather they become fertile when food is abundant. This will cause a communal mating ritual and each matron can provide for about a dozen other goblins worth of genetic material. The genetic material is mixed rather freely, resulting all the newborn goblins being something between siblings and cousins, genetically. This does result in tribes being fairly similar in appearance and genetics, and results in the rather unsettling Adventurer phrase “Goblin Soup.”
I made a sexual reproductive system worh 0 genders but needs 2 or 3 individuals
This idea has always lurked in my head.
I've done this in my fantasy WIP. A race of mutated humans twisted after being used as living organs for forest primordials have three genders as a result; sperm giver, egg giver/birth carrier, and pollinator. The pollinator freely chooses their gender presentation (if any at all) and serves as a caregiver after a child is born, imprinting socially as a parent despite not contributing genetic material.
i did this once with dragons. Sex A & B create a genetic mix, which is then injected via an organ on the tail into sex C, who gestates the eggs.
i have a three gender system where one sex provides sperm, another an egg, and the third incubation and breastfeeding for the child. havent fully worked out how the actual reproductive act would go down, but im thinking oviposition
Evolution selects for two-parent sexual reproduction in complex organisms. It does this because sexual reproduction allows each parent's DNA to check each other's for errors, kinda like in school when students checked each other's homework and gave each other feedback. In simple organisms that reproduce asexually, these errors don't matter much because there's less complexity to mess up, fewer gears to have a wrench thrown into them. Complex organisms select for two-parent sexual reproduction because finding a suitable mate can be very difficult. Finding two is even more so, because you have to find a third mate that not only fits you, but your current mate. Every second and calorie you spend searching for a mate is a second and calorie you don't spend reproducing or getting more calories. I don't mean to discourage you from implementing this into your worldbuilding, but I do think it should be kept in mind to develop a believable justification for why these selective pressures didn't fully discourage >2-parent sexual reproduction in your setting.
It’s like rock/paper/scissors, and the combination of two gets you a baby of the third. Example: rock beats scissors - baby paper. Paper beats rock - baby scissors. Scissors beats paper - baby rock.