4 ms·
Once you exclude the nasty effects of inbreeding, what's the evidence that mixing leads to healthier offspring?
by danielweber 12y ago
Once you exclude the nasty effects of inbreeding, what's the evidence that mixing leads to healthier offspring?
- api 12y agoIt's actually a very complex subject. Start with things like outbreeding, heterozygote dominance, etc. https://en.wikipedia.org/wiki/Outcrossing https://en.wikipedia.org/wiki/Outcrossing https://en.wikipedia.org/wiki/Inbreeding_depression https://en.wikipedia.org/wiki/Inbreeding_depression https://en.wikipedia.org/wiki/Heterosis https://en.wikipedia.org/wiki/Heterosis There are of course counter-cases. Nothing in biology is totalistic or absolute, including this sentence. :) https://en.wikipedia.org/wiki/Outbreeding_depression https://en.wikipedia.org/wiki/Outbreeding_depression Yet most of the evidence I've seen e.g. in immunology (which doesn't suffer from the PC bias against studying it like IQ) suggests that on average outbreeding tends to boost fitness to some extent. More distant crosses tend to have healthier immune systems... again on average. To a great extent outbreeding is the entire point of sexual reproduction-- to use mating assortment to decrease the likelihood of being stuck with lower-fitness genes that keep repeating in the same lineage. If it didn't work that way we'd probably all reproduce by budding. Edit: wacko left-field hypothesis: what if the immune system boosting effects of outbreeding have helped the human race avoid a global super-plague brought on by unprecedented degrees of mobility? In other words-- what if the genetic effects of all that mobility have counter-balanced the immunological risks?
- aswanson 12y agoThat's kind of like asking what's the evidence that smoking leads to cancer. Genetics works probabalistically; the chance that a deleterious mutation gets expressed increases for each generation of closed breeders.