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Study: Animals do not usually try to avoid mating with their own kin


Contrary to widespread belief among biologists, according to authors of a recent wide-ranging study:

Biologists have long believed that it’s adaptive for most species to avoid mate pairings between close kin because of the potential genetic fallout, but a meta-analysis published May 3 in Nature Ecology & Evolution challenges this long-held assumption…

The finding also bolsters what were previously considered to be unexpected findings of frequent inbreeding or a lack of inbreeding avoidance in some wild populations.

The authors examined nearly 140 experimental studies of inbreeding avoidance conducted on 88 species—everything from fruit flies to humans—and found little evidence that animals on the whole prefer non-relatives.

Christie Wilcox, “Incest Isn’t Taboo in Nature: Study” at The Scientist

The paper is open access, via a SharedIt token.

Thing is, it was never clear exactly what the mechanism is supposed to be for animals to try to avoid mating with kin. So it’s no surprise that most aren’t really doing that anyway.

Maybe if researchers focus on situations where breeding with close kin can really be shown to be happening, they can identify how the animals know. Then try to find out how such mechanisms would come to exist.

One problem with Darwinian thinking is that theory comes first and then evidence is found for it. That seems to have happened with beliefs about animals avoiding mating with kin.

Even author Regina Vega-Trejo falls into that trap when discussing the comparatively smaller number of animal species that prefer to mate with kin:

One of the things to keep in mind is that when you make a decision to mate or to reproduce, what you basically want is to pass on your genes. And half of your genetic material will go to your offspring, but the other half of the genetic material will come from your partner. And if you mate with your brother, for example, you’re actually passing on more genes that belong to you [because he has some of the same genes]. So, that might be one of the things that animals—I mean, they don’t think or consider—but that’s one of the advantages [of inbreeding].

Christie Wilcox, “Incest Isn’t Taboo in Nature: Study” at The Scientist

No, indeed. The animals don’t “think or consider.” They also don’t want to pass on their genes. That’s ultra-Darwinian nonsense. They want to mate and whatever happens is what happens. Darwinian nonsense around a drive to pass on genes simply clouds the picture.

See also: Mice from opposite coasts of North America show the same changes in genes. The house mouse, beloved of cats, only arrived in North America with Europeans, so there aren’t millions of years to make up a story about how things happened.

Oh, do note that amongst hyenas the "pack leader" is ALWAYS female, and she is the ONLY female allowed to mate, regardless of how many males are in the pack. As far as I know, this is unique across other species. So, smile at our Earth Mother and marvel at Her diversity, which She creates for our entertainment. mahuna
Interesting aspect regarding the Earth Mother. I know the Greeks strongly believed in something similar to there being a difference between sex and pregnancy. Other places, like the Zulus, knew before any European ever met them, since the father had the higher importance than the mother. It was the father who determined the tribe, which is why Shaka was always considered Zulu, even though his mother was from a different tribe. BobRyan
Thanks Mahuna for comments that finally pushed me to register. I'm not sure what sources you are using, but the overwhelming evidence from the data from the contact with primitive tribes throughout the world in the 1700s and 1800s is that the most primitive societies primarily worshiped single deity, a male Sky God. (Some tribes had animism and spirits and occasionally some lesser gods but this Sky God was the creator). Interestingly, the most primitive believed that this Sky God created the world, used to live among people in the very distant past until people did something wrong (what that wrong this was varied greatly), had moral requirements for people, and MOST INTERESTINGLY you were forbidden to make an image of this Sky God (something contrary to much human nature). For resources - Search for "Primitive Monotheism" and Wilhelm Schmidt. Monotheism in history. Also Arthur Custance has some great articles on this. preceded polytheism which later finally returned to monotheism. Think about hinduism - the earlier vedas only had a few gods which later turned to hundreds. The early Egyptian book of the dead was far more monotheistic (although still had multiple gods I think) than much later works which were highly polytheistic. The data is in sharp contrast to the theories of intellectuals in the late 1800s that posited that religion evolved (heavily influenced by Darwinism). They had these theories despite overwhelming evidence from the most primitive tribes that showed the opposite. look at the odds
When the English arrived in Australia, one of the MANY things that surprised them was that the Abos did NOT know that having babies had ANYTHING to do with intercourse. It was just a fun game. The same was true for all the early societies we've studied. The key is that ALL of the original Deities were FEMALE, beginning with the Earth Mother: from time to time the Earth Mother, who was a REALLY nice lady, simply GAVE one of Her daughters a baby to play with. The guys, who didn't really like the Earth Mother, sat on the other side of campfire and grumbled. Then SUDDENLY someone (most likely a GUY) came up with a convincing argument for men's role in making babies, and the Earth Mother now played second fiddle to the Sky God. In many cultures, including Judeo-Christianity, the Sky God rules ALONE. And there ISN'T any Earth Mother, although a lot of Christian sects have effectively made Mary an Earth Mother. mahuna
Humans, being different from animals, have a choice to act out on sexual impulse, which animals do not possess. It is one piece of evidence to support free will of many. Animals do not make choices about what is moral and what is not. Animals are what their nature intends them to be through design. BobRyan
Most life forms have strong mechanisms to spread the progeny far and wide, so there's no good reason to have an internal preference. Seeds are blown by wind or transported by birds. Vertebrate mothers push their kids out of the nest when ready. The swarming stage of insects has wings. polistra

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