# Menage a Trois **URL:** \ **Category:** Factual Questions\ **Created:** [April 26, 2000, 3:45am UTC](https://boards.straightdope.com/t/menage-a-trois/11221 "2000-04-26T03:45:00Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![Cabbage](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@Cabbage](https://boards.straightdope.com/u/Cabbage)\ **Post date:** [April 26, 2000, 3:45am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/1 "2000-04-26T03:45:00Z")
Well, not really: When life began, reproduction was asexual. After some evolution, sexual reproduction became possible, which has, as one of its benefits, more mixing of the gene pool (strengthening the species as a whole), producing more variety and basically “helping” evolution along, as I understand it. Anyway, how likely is it that somewhere down the evolutionary line some species may eventually have three (or more) “sexes” necessary to reproduction? Could this possibly be significantly more advantageous than requiring only two sexes to reproduce? * * * …ebius sig. This is a moebius sig. This is a mo… (sig line courtesy of WallyM7) ---
**Author:** ![SingleDad](https://avatars.discourse-cdn.com/v4/letter/s/9e8a1a/32.png) [@SingleDad](https://boards.straightdope.com/u/SingleDad)\ **Post date:** [April 26, 2000, 3:55am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/2 "2000-04-26T03:55:00Z")
I don’t think so. If trisexual reproduction had much evolutionary advantage, one expects it would be widespread by now. ---
**Author:** ![Steve-o](https://avatars.discourse-cdn.com/v4/letter/s/ecc23a/32.png) [@Steve-o](https://boards.straightdope.com/u/Steve-o)\ **Post date:** [April 26, 2000, 4:07am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/3 "2000-04-26T04:07:00Z")
I think **SingleDad** ’s right. I can’t think of any advantages that would outweigh the fun… er… I mean trouble. * * * Things are random only insofar as we don’t understand them. ---
**Author:** ![Jophiel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jophiel/32/66_2.png) [@Jophiel](https://boards.straightdope.com/u/Jophiel)\ **Post date:** [April 26, 2000, 4:29am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/4 "2000-04-26T04:29:00Z")
To elaborate slightly: Trisexual reproduction adds a whole new facet to the game that it’s doubtful could ever be an advantage. While I suppose it would result in greater genetic diversity, the act of getting three seperate beings together to mate successfully isn’t something likely to happen (successful mating meaning that all three do their seperate parts to making a new creature, not just having a good time). Unless there was some major restructuring of the reproductive organs, imagine that the female had to be fertilized by the male, and then the male’s sperm had to be activated by another mating between the female and the “male-2” (for lack of a better term). This is twice as much work (if not more) for something that’s been working out well enough already with simply a male and a female. On the other hand, m/f reproduction beats out asexual reproduction due to the mixing of genetic materials and the chance for healthier creatures to pass on their genes while the weaker ones are deprived of a chance to mate. And it’s more fun. * * * “I guess one person can make a difference, although most of the time they probably shouldn’t.” ---
**Author:** ![TheNerd](https://avatars.discourse-cdn.com/v4/letter/t/858c86/32.png) [@TheNerd](https://boards.straightdope.com/u/TheNerd)\ **Post date:** [April 26, 2000, 6:18am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/5 "2000-04-26T06:18:00Z")
Empirically, genetic algorithms gain very little, if any (depends on the application/implementation), effectiveness when the number of parents per offspring is raised above two. ---
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [April 26, 2000, 7:11pm UTC](https://boards.straightdope.com/t/menage-a-trois/11221/6 "2000-04-26T19:11:00Z")
Actually, just the other night I was visiting a web site that documented trisexual reproduction amongst humans. The females looked either enthralled or in pain. 😃 😃 😃 * * * You must unlearn what you have learned. – Yoda ---
**Author:** ![Oblong](https://avatars.discourse-cdn.com/v4/letter/o/c0e974/32.png) [@Oblong](https://boards.straightdope.com/u/Oblong)\ **Post date:** [April 26, 2000, 7:33pm UTC](https://boards.straightdope.com/t/menage-a-trois/11221/7 "2000-04-26T19:33:00Z")
Darn. I thought this topic was going to tell me how to convince my wife… ---
**Author:** ![Weirddave](https://avatars.discourse-cdn.com/v4/letter/w/919ad9/32.png) [@Weirddave](https://boards.straightdope.com/u/Weirddave)\ **Post date:** [April 26, 2000, 8:33pm UTC](https://boards.straightdope.com/t/menage-a-trois/11221/8 "2000-04-26T20:33:00Z")
The newcomers who live in LA use tri-sexual reproduction. I saw a documentary on tv… * * * Cecil said it. I believe it. That settles it. * * * Relax, I’m not as Dave as I look!- A Wallified sig! ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [April 26, 2000, 9:43pm UTC](https://boards.straightdope.com/t/menage-a-trois/11221/9 "2000-04-26T21:43:00Z")
A Piers Anthony book (I don’t recall the title as I read it about 15 years ago) had as one of its central themes a tri-sexual race. Here’s how it worked: Any two of the three ‘types’ of being could be around each other with no trouble. As soon as the third type showed up all three instantly engaged in sexual reproduction. They couldn’t help themselves and there was no stopping it. As a result the species had developed an elaborate system of pathways and what-not that ensured their were never more than two types of being present at any given time. Presumably there were sanctioned areas where one went when one wanted to reproduce. Hey…ya never know! Could happen! ---
**Author:** ![maralinn](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@maralinn](https://boards.straightdope.com/u/maralinn)\ **Post date:** [April 26, 2000, 9:59pm UTC](https://boards.straightdope.com/t/menage-a-trois/11221/10 "2000-04-26T21:59:00Z")
I think Dawn: Xenogenesis by Octavia Butler involves tri-sexual reproduction too, and has some interesting ideas on why it might be an evolutionary advantage. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [April 27, 2000, 12:02am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/11 "2000-04-27T00:02:00Z")
_Walk the Moons Road_ by Jim Aiken also covered the concept. The same with the TV series _Alien Nation_. It’s not exactly a new concept. The best (and most hilarious) version was Ed Subitzky’s _Saturday Night on Antares, the Planet with 12 Different Sexes_ in the _National Lampoon_. You think _you_ have trouble . . . . * * * “What we have here is failure to communicate.” – Strother Martin, anticipating the Internet. [www.sff.net/people/rothman](http://www.sff.net/people/rothman) ---
**Author:** ![JonF](https://avatars.discourse-cdn.com/v4/letter/j/cab0a1/32.png) [@JonF](https://boards.straightdope.com/u/JonF)\ **Post date:** [April 27, 2000, 12:44am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/12 "2000-04-27T00:44:00Z")
Don’t forget John Varley’s “titanides” in _Titan_, _Wizard_, and _Demon_. * * * jrf ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [April 27, 2000, 1:51am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/13 "2000-04-27T01:51:00Z")
“Venus and the Seven Sexes” is a story by William Tenn (the pen name of Philip Klass). * * * …this is another Moebius sig…b!s sn!qaoW jay+oue s! s!y+… (adaptation of a _WallyM7Sig™_ a la quadell) For business reasons, I must preserve the outward signs of sanity. - Mark Twain ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 27, 2000, 2:16am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/14 "2000-04-27T02:16:00Z")
Ok, as much as I love sci-fi (and check out _The Gods Themselves_, by Asimov, btw), there are some real-world examples. There’s a species of fungus (don’t have my biology book handy, sorry) that actually has 17 known sexes. It only takes two, but any two fungi of different sex can mate. * * * “There are only two things that are infinite: The Universe, and human stupidity-- and I’m not sure about the Universe” –A. Einstein ---
**Author:** ![JoltSucker](https://avatars.discourse-cdn.com/v4/letter/j/d2c977/32.png) [@JoltSucker](https://boards.straightdope.com/u/JoltSucker)\ **Post date:** [April 27, 2000, 2:17am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/15 "2000-04-27T02:17:00Z")
I’ve often wondered if the genetic role of the female was to preserve the genetic line, and the role of the male to introduce change. Or stated a different way, the female brings genetic stability, the male shakes things up. Look at mitochondria (sp?), which is passed down infinitely from generation to generation **along maternal lines**. Maybe it’'s the interplay between static and chaotic that makes for successful evolution. In a tri-sexual species, what could be the three functions? ---
**Author:** ![moriah](https://avatars.discourse-cdn.com/v4/letter/m/b2d939/32.png) [@moriah](https://boards.straightdope.com/u/moriah)\ **Post date:** [April 27, 2000, 9:55pm UTC](https://boards.straightdope.com/t/menage-a-trois/11221/16 "2000-04-27T21:55:00Z")
> [@](#): > > Originally posted by Jeff\_42: > \*\*A Piers Anthony book (I don’t recall the title as I read it about 15 years ago) had as one of its central themes a tri-sexual race. Here’s how it worked: > > Any two of the three ‘types’ of being could be around each other with no trouble. As soon as the third type showed up all three instantly engaged in sexual reproduction. They couldn’t help themselves and there was no stopping it.\*\* Ahhh, love how Piers Anthony (and Robert Heinlein for that matter) play out their Freudian fantasies (and nightmares) in their so-called legit Sci-Fi books. Free sex, forced sex, sexism, and misogyny all become legit when they’re part of an alien culture. ## Peace. _And before I’m attacked by any rabid Heinlein fan, I must warn you, I read Number of the Beast – it’s stinks it does._ ---
**Author:** ![JoltSucker](https://avatars.discourse-cdn.com/v4/letter/j/d2c977/32.png) [@JoltSucker](https://boards.straightdope.com/u/JoltSucker)\ **Post date:** [April 28, 2000, 3:23am UTC](https://boards.straightdope.com/t/menage-a-trois/11221/17 "2000-04-28T03:23:00Z")
I could see a species evolving, where the female was impregnated twice. After the first fertilization, the egg wouldn’t be a true embryo, but a kind of meta-egg. It would take the second impregnation to form a true embryo. It’s still an embellishment on male and female, but in that scenario there would be two **types** of male. Perhaps this would arise if there was a evolutionarily successful cross-species mating. Male and female of species A mate, and before much in the way of cellular differentiation happens, a male from species B mates with the pregnant female of species A. The sperm of species B invades the embryo that the female carries, and basically infects it with its genetic material, much like a retrovirus. Only this time, a successful new creature is formed. If enough of these cross-species two stage matings happen, a breeding population is formed, with the female of species A\*B “expecting” to be impregnated in two stages. The first type of male would be mostly species A-like, and the second type of male would be mostly species B-like. Wierd, but feasible, I suppose. Any geneticists out there?