Actually many states allow for cousins to marry. Just sayin'.
I find it ridiculous that people oppose, say...gay marriage, but in several states you can marry your cousin.
This is a sad yet amusing map of where you can marry your cousin or your same sex partner, whatever floats your boat.
http://mgcomplaints.com/wp-content/uplo ... s-2011.jpg
Notice how many states still allow it! Just nobody ever talks about it, lol.
If I recall properly (and I might be off, apologies if I am) humans went through an evolutionary "bottleneck" at one point, so the entire species descends from less than 50,000 individuals.
Cheetahs had it worse...their whole species descends from three individuals, a mother and two male cubs.
Every cheetah alive is so genetically similar to every other cheetah it isn't even funny. Genetically they are all "identical twins."
All Taki (also known as Mongolian Wild Horses) descend from just nine individuals...the species was nearly extinct in captivity and was TOTALLY extinct in the wild, they've since recovered and have been released back into the wild, their species is now thriving.
The reason inbreeding/linebreeding is "bad" is because it will enhance everything due to limited genetic variability. If you want a good trait to be more prevalent, linebreed. However if there are latent negative traits, they will also become more prevalent. With human inbreeding it doesn't take many generations to constrict the genetic variability to where it isn't viable. My mother and father were unlucky, while not related they had the same recessive genetics to have very flawed children...their first two children were born without lung alveoli, meaning they could not make oxygen exchange, and they suffocated moments after birth. In their case it was a very unlucky coincidence, but it has relevancy on inbreeding in humans...inbreed too often and that rare recessive trait for rapid-death-at-birth becomes a LOT less rare.
HOWEVER, when practiced by people who are breeding animals and done very, very responsibly, it is totally harmless...and if done right with a strong rule of culling, can lead to nearly perfect specimens.
<br /><br />__________ Mon Jul 02, 2012 1:06 pm __________<br /><br />Oh man, I was WAY off!!! The bottleneck for the human species was a lot tighter than I remember.
Humans
The Toba catastrophe theory suggests that a bottleneck of the human population occurred c. 70,000 years ago, proposing that the human population was reduced to perhaps 15,000 individuals[3] when the Toba supervolcano in Indonesia erupted and triggered a major environmental change. The theory is based on geological evidences of sudden climate change and on coalescence evidences of some genes (including mitochondrial DNA, Y-chromosome and some nuclear genes)[4] and the relatively low level of genetic variation with humans.[3]
However, such coalescence is genetically expected and does not, in itself, indicate a population bottleneck, because mitochondrial DNA and Y-chromosome DNA are only a small part of the entire genome, and are atypical in that they are inherited exclusively through the mother or through the father, respectively. Most genes in the genome are inherited from either father or mother, and thus can be traced back in time via either matrilineal or patrilineal ancestry.[5] Research on many genes finds different coalescence points from 2 million years ago to 60,000 years ago when different genes are considered, thus disproving the existence of more recent extreme bottlenecks (i.e., a single breeding pair).[3][6]
On the other hand, in 2000, a Molecular Biology and Evolution paper suggested a transplanting model or a 'long bottleneck' to account for the limited genetic variation, rather than a catastrophic environmental change.[7] This would be consistent with suggestions that in sub-Saharan Africa numbers could have dropped at times as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the Late Stone Age.[8]
From the wikipedia on genetic bottlenecks:
http://en.wikipedia.org/wiki/Population ... eck#Humans
