Funny thing is, all the folks who should be using "folk genetics" weren't-- they used morality, to the point of not being able to marry your parent's kids-- while the folks who should be using actual science think Deliverance is a documentary. (*headdesk* over and over at the idea of Down's being caused by cousin-marriage....)
Hm. Thinking on it a bit more, possibly the folks further back were more familiar with applied genetics? Crossbred Vigor is not exactly obscure; you breed your stock for some traits, and then bring in a totally different line that has similar traits every couple of generations for best results.
My folks breed cows; their replacements all come from among the daughters of the herd.* 15 years ago, they switched to only certified Black Angus, with the largely-angus-but-also-a-lot-of-other-stuff stock. About five years ago, they started to worry about finally losing the hybrid vigor-- given their druthers, they'd start buying Hereford bulls for one reproductive cycle. Only partly because there are very few things cuter than a little herford calf... I'd even pit them against the random fluke of a red Angus.
In contrast, my mom does AI work for some very smart people who don't even think about the genetics of what they're doing. They'd breed daughter and granddaughter and great granddaughter (and, I think, three more generations now--not sure what calves were female the last several years) on the same bull, just because they don't think about where the straws came from, they just ordered a bunch of straws on whatever-the-heck breed they wanted years ago.
So, to kind of reach a point, if you assume fairly closed human populations, even out-breeding is less of a good idea if your mother married an outsider....
Then again, the not-as-big-a-good-the-second-generation-in-a-row isn't exactly a good reason to forbid something, while the issue of really bad recessive genes is.
*It's actually pretty slick-- when the replacements are two, they're bred with the newest bulls, who are smallest; those calves are almost never kept, and rare exceptions are easy to track and just AI. Next year, the bulls go to one of the other breeding groups, and are usually sold the year their daughters would cycle into the general population. Not just for genetic reasons, but also because the bulls just keep growing and they can eventually hurt the cows. Different ranchers tend to a different size of cow.
no subject
Hm.
Thinking on it a bit more, possibly the folks further back were more familiar with applied genetics? Crossbred Vigor is not exactly obscure; you breed your stock for some traits, and then bring in a totally different line that has similar traits every couple of generations for best results.
My folks breed cows; their replacements all come from among the daughters of the herd.* 15 years ago, they switched to only certified Black Angus, with the largely-angus-but-also-a-lot-of-other-stuff stock. About five years ago, they started to worry about finally losing the hybrid vigor-- given their druthers, they'd start buying Hereford bulls for one reproductive cycle. Only partly because there are very few things cuter than a little herford calf... I'd even pit them against the random fluke of a red Angus.
In contrast, my mom does AI work for some very smart people who don't even think about the genetics of what they're doing. They'd breed daughter and granddaughter and great granddaughter (and, I think, three more generations now--not sure what calves were female the last several years) on the same bull, just because they don't think about where the straws came from, they just ordered a bunch of straws on whatever-the-heck breed they wanted years ago.
So, to kind of reach a point, if you assume fairly closed human populations, even out-breeding is less of a good idea if your mother married an outsider....
Then again, the not-as-big-a-good-the-second-generation-in-a-row isn't exactly a good reason to forbid something, while the issue of really bad recessive genes is.
*It's actually pretty slick-- when the replacements are two, they're bred with the newest bulls, who are smallest; those calves are almost never kept, and rare exceptions are easy to track and just AI.
Next year, the bulls go to one of the other breeding groups, and are usually sold the year their daughters would cycle into the general population. Not just for genetic reasons, but also because the bulls just keep growing and they can eventually hurt the cows. Different ranchers tend to a different size of cow.