Insight on the Andorian four-gender paradigm?

[rfmcdpei]

I probably wasn't alone in thinking of the Andorians when I heard about the seven sexes of the protozoa Tetrahymena thermophilia. Discoblog seemed to summarize the mathematics and origins of these seven sexes well.

Tetrahymena thermophila, which in addition to its seven different sexes—conveniently named I, II, III, IV, V, VI, and VII—has such a complex sex life that it requires an extra nucleus. This fuzzy, single-celled critter has a larger macronucleus that takes care of most cellular functions and a smaller micronucleus dedicated to genetic conjugation. The other odd thing about this one-celled wonder is that the population of the seven sexes are skewed, leading Unversity of Houston researcher Rebecca Zufall and her colleagues to ask: What gives?
To answer that question, they created mathematical models of T. thermophila populations, and discovered that different versions of the same gene, or alleles, gave advantages to different sexes. Unlike humans, in which an individual’s sex is fully determined by its genes, the genotypes of these creatures provide only probabilities of developing certain sexes—probabilities that are influenced partly by genetics and partly by surrounding temperatures. The sex-influencing gene is called mat, and different alleles make certain sex types more likely than others: A T. thermophila born with the mat2 allele, for example, has no chance of becoming type I, a 15% chance of being type II, a 9% chance of developing into type III, and so forth. For convenience, this mat2 gene variety and the other 13 known alleles are also grouped into an A-group or a B-group: The A-group alleles lead to the I, II, III, V, and VI sexes, and the B-group alleles to the II, III, IV, V, VI, and VII sexes. In terms of evolutionary advantages, the researchers’ models back up exactly what we’d expect: The alleles that produce a variety of sexes outcompete the alleles that produce only one; variation is a nice thing to have, after all.


Epilogue: You may still be wondering why a species would have seven sexes; researchers are wondering the same thing. Some past research suggests that it’s to maximize the choice of sexual partners (pdf), since partners must be of a different sex type. The jury’s still out as to why they’re specifically at the seven-sex level now. Tiago Paixão, the study’s lead author, says that “one possible answer is that this is the number of sexes that populations of T. thermophila typically support, and further increases in number of sexes would not lead to any noticeable increase in fitness.”


That said, keep in mind that scientists are playing loose with the term “sex” when they define these protozoa; as Cleveland State University professor F. Paul Doerder and his colleagues write (pdf), “To recognize suitable partners, ciliates [such as T. thermophila] are differentiated into mating types, a kind of self-not-self discrimination system, as opposed to true sexes.”

Assuming that the mating patterns of protozoa would be relevant for the much more complex Andorians, this implies that Andorian/Aenar evolution must have been very competitive. (It also explains why there aren't any Andorian/non-Andorian hybrids, if the protozoa above need an extra cell nucleus to reproduce; advanced interspecies reproductive medicine must encounter barriers somewhere.)


Ideas as to how this could have developed?

 

[hbquikcomjamesl]

Wait a second: don't Sulamids have twelve sexes (according to Memory Beta; I thought it was only five), all of whom claim to be "male," especially those that bear children?

 

[Smellincoffee]

Recently while reading Galileo's Finger, I think I saw a reference to a multi-sex species which used multiple partners as a way of limiting the effect of harmful mutations.

 

[Christopher]

Recently while reading Galileo's Finger, I think I saw a reference to a multi-sex species which used multiple partners as a way of limiting the effect of harmful mutations.

Hmm, that's the same rationale I came up with for a multiple-sex species (and I don't remember whether I actually used it in Over a Torrent Sea, though I know I thought about doing so). My idea was that with multiple copies of each gene, any mutation in a gene is likely to be "outvoted" by the majority. So it would be a good adaptation for species on planets with higher levels of radiation or toxic substances, say.

 

[Deranged Nasat]

Recently while reading Galileo's Finger, I think I saw a reference to a multi-sex species which used multiple partners as a way of limiting the effect of harmful mutations.

Hmm, that's the same rationale I came up with for a multiple-sex species (and I don't remember whether I actually used it in Over a Torrent Sea, though I know I thought about doing so). My idea was that with multiple copies of each gene, any mutation in a gene is likely to be "outvoted" by the majority. So it would be a good adaptation for species on planets with higher levels of radiation or toxic substances, say.

You did indeed include this reasoning in "Over a Torrent Sea".

 

[rfmcdpei]

Wait a second: don't Sulamids have twelve sexes (according to Memory Beta; I thought it was only five), all of whom claim to be "male," especially those that bear children?

I'd forgotten about them!

Recently while reading Galileo's Finger, I think I saw a reference to a multi-sex species which used multiple partners as a way of limiting the effect of harmful mutations.

Hmm, that's the same rationale I came up with for a multiple-sex species (and I don't remember whether I actually used it in Over a Torrent Sea, though I know I thought about doing so). My idea was that with multiple copies of each gene, any mutation in a gene is likely to be "outvoted" by the majority. So it would be a good adaptation for species on planets with higher levels of radiation or toxic substances, say.

And as it turns out, Andor is a moon of a gas giant that itself has a very strong magnetic field. Might the planet have above-average levels of radiation?

This still leaves unanswered the question of where the other four-gender species on Andor went. According to Paradigm, Andorians were unique in this regard, the first sign of a four-gender species being a flowering plant found in a nature reserve in the course of the action. Transplantation?

 

[DS9Continuing]

Hmm, that's the same rationale I came up with for a multiple-sex species (and I don't remember whether I actually used it in Over a Torrent Sea, though I know I thought about doing so). My idea was that with multiple copies of each gene, any mutation in a gene is likely to be "outvoted" by the majority. So it would be a good adaptation for species on planets with higher levels of radiation or toxic substances, say.

You did indeed include this reasoning in "Over a Torrent Sea".

I thought you used it in Orion's Hounds, myself, not OaTS, in the procreating-starjellies scene. Troi explained it to Riker while fighting off a psychically-induced orgasm.

Either way, if that is indeed the reason behind multi-sex species, then it kinda backfired in the case of the Andorians, didn't it?

We still haven't really had answered the question of WHY the Andorians are having these problems, have we? Is it environmental? The result of industrial pollution? Just a flaw in the basic genetic code? That would provide a bsis from which to start looking for clues to a solution.

 

[Christopher]

I thought you used it in Orion's Hounds, myself, not OaTS, in the procreating-starjellies scene.

No, that was a loosely similar concept, but the idea there was that the star-jellies (which are all essentially parthenogenetic) consciously engineer the genome of their offspring in a group creative process. What I'm talking about is an evolutionary adaptation that serves to minimize the risk from mutation by probabilistic means, not something that has any conscious will behind it.

We still haven't really had answered the question of WHY the Andorians are having these problems, have we? Is it environmental? The result of industrial pollution? Just a flaw in the basic genetic code? That would provide a bsis from which to start looking for clues to a solution.

I thought a part of it was that the total number of offspring produced by each quad was typically less than four, so that it fell short of the replacement rate necessary to maintain a stable or growing population size. Maybe something to do with the duration of the window for procreation being too short, or with the difficulties of finding four compatible partners as opposed to just two.

 

[DS9Continuing]

We still haven't really had answered the question of WHY the Andorians are having these problems, have we? Is it environmental? The result of industrial pollution? Just a flaw in the basic genetic code? That would provide a bsis from which to start looking for clues to a solution.

I thought a part of it was that the total number of offspring produced by each quad was typically less than four, so that it fell short of the replacement rate necessary to maintain a stable or growing population size. Maybe something to do with the duration of the window for procreation being too short, or with the difficulties of finding four compatible partners as opposed to just two.

Yes, certainly, that's the immediate cause. But hadn't there been some mention that it hadn't always been so? That the production of enough offspring to balance the population (obviously, a minimum of four children per quad) used to be perfectly achievable because the reproductive window wasn't too small, but that something changed and that window became too small? And that's in addition to chromosomal abnormalities and birth defects? So what caused that change in the amount of time for which an Andorian is safely fertile? I'm not sure that aspect of it has been answered yet.

 

[rfmcdpei]

We still haven't really had answered the question of WHY the Andorians are having these problems, have we? Is it environmental? The result of industrial pollution? Just a flaw in the basic genetic code? That would provide a bsis from which to start looking for clues to a solution.

I thought a part of it was that the total number of offspring produced by each quad was typically less than four, so that it fell short of the replacement rate necessary to maintain a stable or growing population size. Maybe something to do with the duration of the window for procreation being too short, or with the difficulties of finding four compatible partners as opposed to just two.

Yes, certainly, that's the immediate cause. But hadn't there been some mention that it hadn't always been so? That the production of enough offspring to balance the population (obviously, a minimum of four children per quad) used to be perfectly achievable because the reproductive window wasn't too small, but that something changed and that window became too small? And that's in addition to chromosomal abnormalities and birth defects? So what caused that change in the amount of time for which an Andorian is safely fertile? I'm not sure that aspect of it has been answered yet.

Agreed. In one of the early DS9 relaunch novels, Charivretha told Ro that the four-gender paradigm worked, but that certain recent changes made it non-viable. No, she didn't specify which changes.

It's not a matter of social change so far as we know, since Andorians seem to want to become parents. Something to do with the environment on Andor doesn't seem very likely, since this biological syndrome seems to afflict Andorians living off-world as well. The accumulation of genetic errors?