Incest taboos: do animals have them?

November 1, 2009 2:07 AM

How common is incest in the animal kingdom?

Do lion cubs of the opposite sex mate with one another? Will a mother bird mate with her son? Do related domestic animals tend to mate with one another without any encouragement from humans?

posted by thisperon to Science & Nature (14 answers total)

The plural of anecdote is not data. Having said that, I have had to separate male garter snakes from their female siblings because they were trying to mate with them. (At the time I wasn't sure of each snake's sex; behaviour very quickly determined who was who. Afterward, I called this the "hey, get off your sister" method of sex determination.) Now, snakes aren't very smart, don't have any social structures, and don't form family bonds; I infer that random chance keeps them from inbreeding too much in the wild.
posted by mcwetboy at 2:39 AM on November 1, 2009 [1 favorite]

Hells yes , but not as much as you might think. Dare I say, not willy nilly.

Money quote:

Aside from microbes, most of which reproduce asexually, Wheelwright said mountaintops, small islands and other isolated habitats are places where today's incestuous reproducers are most commonly found. "If your relatives are the only game in town you don't have much of a choice," he said.

Anecdotally, coming from farming stock as I do (this isn't going where you think it is!!), animals will try it on with each other any time they get the chance, the randy little bastards. And in the absence of better alternatives. mother, father, uncle, sister, brother - whatever, they don't care.
posted by smoke at 3:07 AM on November 1, 2009 [1 favorite]

Does the Bible say who Cain and Abel ended up with?

When I was a kid I had pet guinea pigs, so... yeah.
posted by moorooka at 3:11 AM on November 1, 2009

I suspect that the ratio of incestuous matings between siblings is in direct proportion to the number of non-siblings as opposed to siblings.....
posted by HuronBob at 3:16 AM on November 1, 2009

I took the brave route, and googled animal+incest. The first three entries were pornography, but the fourth yielded this article: Incest Not So Taboo in Nature. There's no actual data or percentages given, but it does mention three things that will interest you.

1. The evolutionary biologist they interviewed contends that asexual reproduction is the ultimate incest from a genetic point of view (a good point).
2. African fish inbreed. That is linked to another article, here.
3. Incest in the animal world rarely gives genetic advantage to an animal (but see African fish for an exception), so when it occurs it's usually because the animal is isolated from a large population. In other words, there's no other option for reproducing.

There seemed to be many more scientifically-leaning articles mixed in with the porn in the google results, so that might be a start for you.
posted by Houstonian at 3:19 AM on November 1, 2009 [4 favorites]

Acarophenax tribolii, a species of mite, practises a really fascinating form of incest.
- sex ratios are skewed - ~ 15:1 females to males
- all mating is brother-sister
- all mating occurs inside the mother's womb

And then I think once they are mature they burst out of the mother's body. But that may just be my imagination.

Stephen Jay Gould discusses them in chapter 6 of The Panda's Thumb raised as proof of the forces which drive gender ratios. It is theorised that unequal gender ratios will only occur in exclusively incestuous species, because then there is no advantage to producing anything over the bare minimum of males, and the case of the mites supports this.
posted by schmichael at 4:27 AM on November 1, 2009 [4 favorites]

Keep in mind that behaviors that may look like incest to us—like mounting—are also used to establish dominance hierarchies in many species, even between relatives.

Here's where you should look for recent scholarly literature to avoid... unrelated links.
posted by The Michael The at 4:28 AM on November 1, 2009

Domestic cats will breed with any other opposite sex cat that's available, regardless of their genetic relationship to one another.
posted by zarah at 4:38 AM on November 1, 2009

And domestic dogs will attempt to breed with any other thing that's humpable, regardless of genetic relationship, or in fact ownership of genes.
posted by IAmBroom at 5:11 AM on November 1, 2009 [3 favorites]

there was a nature show on television when i was a kid where they put a camera inside a nest of wild ferrets (or weasels, or stoats or something) and to this day can remember quite clearly the pain on the faces of the baby ferrets while they were getting fucked by the dad ferret. it was pretty horrifying to watch, really.
posted by sergeant sandwich at 6:32 AM on November 1, 2009 [2 favorites]

Former guppy owner here to say: No, I don't think guppies have any sort of taboo along those lines.
posted by limeonaire at 7:16 AM on November 1, 2009 [1 favorite]

I lived on a farm as a kid, and at any given time, we had upwards of a dozen semi-feral barn cats running around, all of whom were related to and reproduced with one another. Sometimes my parents would try to trap and spay/fix the most prolific breeders. There were lots of jokes about how they were all concurrently sisters, mothers, brothers, fathers and cousins.
posted by M.C. Lo-Carb! at 8:24 AM on November 1, 2009

I saw a study one time where biologists tried to find out what members of the opposite sex were the most attractive to various kinds of animals, and they found that given a choice a first cousin was more attractive than either a sibling or a total stranger.
posted by Chocolate Pickle at 10:10 AM on November 1, 2009 [1 favorite]

Response by poster: I want up seriously mark everything as best answer. Thanks people! I had no idea.
posted by thisperon at 12:41 PM on November 1, 2009