We discussed this question on our show
Diana - There are a few adaptations. One interesting one is hyenas. Apparently, female hyenas will only breed with males that have been recently born into their group or who have just recently joined it. And male hyenas will only move to new groups of females to breed. So they've got a sort of social setup which helps to avoid incest. But on a more sort of scientific level, lemurs actually use scent. They use pheromones on their naughty bits to detect who is the most closely related to them and whoís the farthest sort of relation. The females who will actually smell the males and decide ďhe seems perhaps a bit of a close relative. I'm not going to go there.Ē but I think Chris, isnít there also something about mice?
Chris - Well mice is intriguing. The explanation for mice is that the genes which are concerned with smell are found on the same part of the genome as the genes that control how the immune system decorate cells so they can recognise each other. The idea is that if mice smell alike, they probably have a very similar immune system as well. The problem with this is that if you have an immune system that's too similar, it shows you're very genetically related and so, if you have your smell system programmed to recognise someone whoís very closely related to you, it means itís a bad idea to mate with them. People have done experiments: If you take a male mouse and a female mouse, and they're brother and sister, if you force them and you put them in a cage environment where they havenít got any choice, then they will mate with each other and have offspring, but if you introduce a second mouse, so you've got the mouseís brother and then another male mouse that's unrelated, then the mouse will preferentially mate with the one it's not related to. If you introduce the second mouse after the mouse is already mated and is already pregnant, it can abort the pregnancy and then mate with the new mouse. So they are very strongly trying to avoid incest at all cost, it would appear.
Diana - Yeah, thatís interesting. I think itís probably worth mentioning but sometimes it happens the other way. The ancient Egyptian royal family actually used to promote incest because they thought it was a good thing.
Chris - But were there consequences? Presumably there were.
Diana - There were and Tutankhamun of course famously had a club foot as a result.
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