Mordy

I'm hoping more knowledgeable people will jump in here, I've seen 'cursory' arguments against fundamentalists that incest is impossible because the 'gene pool' would have been too small, or whatever. But doesn't this argument cut both ways? If chimps share ~97% dna compared against humans, aren't other human beings 99.99% DNA in relation to each other? Isn't that an argument FOR incest? It doesn't make sense to me at all, and I think this mostly is because scientists are themselves still don't have a good grasp of genetics because it seems to me that incest is simply a fact of life under both systems or none of us would be here, correct?

Please correct me if I'm wrong, but rewind people mating, at some point your screwing your family small group of families yes? And since people with similar allele frequencies would not survive in the ancient / pre-historic past, isn't this a dumb argument to use against either?

Anyways discuss...

Toto

I think that this would do better in either Science and Skepticism or Evolution/Creationism, but I'm not sure which.

Humans all have 100% human genes, but variations on those genes. Incest is a problem because of the tendency for recessive problem genes to express themselves, but incest does happen.

I do not understand "since people with similar allele frequencies would not survive in the ancient / pre-historic past" - why would they not?

Mordy

Because they wouldn't survive right because they were not that medically advanced correct? Think of the pre-mature babies we can save through science today that would have died in the ancient world, would not this have been the same for incestuous matings, i.e. they had no understanding of genetics way way back in the past, it was all about gene propogation, so isn't incest the rule of life?


Isn't that exactly the same as what you just stated here, you said :"Incest is a problem because of the tendency for recessive problem genes to express themselves, but incest does happen." Are they not recessive genes/alleles, so that if incest is the rule, near the beginning these kids would have died because of recessivity until children were born that didn't have recessive gene expression and survived?

Toto

I think you will find a better answer in the Evolution/Creationism forum, so I'm going to bump this over there for a scientific explanation.

Peez

I don't understand. In what way would having a small gene pool make incest "impossible?"What do you mean by "FOR incest?"I am not sure of what you mean by "a good grasp of genetics," but scientists do know quite a bit about inheritance. In particular, the mechanisms responsible for the potential health consequences of "incest" are well understood. I don't know what you mean by "both systems," or by "incest is simply a fact of life," but certainly inbreeding is not an all-or-nothing thing. There are degrees of inbreeding, from brother-sister matings to small isolated populations. In a sense, all matings are inbreeding to some extent, it is just a question of just what extent.If I understand you, yes.There is no particular problem with having "similar allele frequencies," so I don't know what you mean here.

Peez

KeithHarwood

Incest is not a problem so far as evolution is concerned. If close relatives mate the chances of progeny being homozygous in recessive genes is much higher than for unrelated mates. If those genes are advantagous they will be locked into the gene pool much more quickly. If they are disadvantagous, they will be removed much more quickly. This is standard operating procedure in animal and plant breeding.

Atheos

Back in a previous life when I was a fundamentalist preacher I used to believe (and teach) that God created Adam and Eve with perfectly formed chromosomes. This accounted for (1) The fact that humans lived incredibly long lifespans and (2) The fact that men could impregnate their sisters, aunts, cousins, neices (even daughers) etc., without exposing genetic weaknesses. This period of relative genetic purity lasted until the time of Noah because the earth was ostensibly protected from the radiation of the sun by an alleged "water canopy". The water canopy was collapsed by God in order to produce the great flood of Noah's day. The sun's radiation then effected human DNA, causing (1) increasingly shorter life expectancy and (2) increased risk of birth defects in cases of incest.

Mighty fine speculation, too bad none of it was consistent with anything proven by geological or fossil records.

-Atheos

peacock's tale

this is exactly what sexual selection tries to tackle and i'm sure you would have some fun reading The Red Queen by Matt Ridley. incest is usually frowned upon in nature, no matter where you look, except for us! one theory says that incest has been used for concentrating wealth and power, as is evident with royals (and luke skywalker) - and an obvious consequence is haemophilia. there's plenty of evidence that suggests sex is used by most organisms (except many plants, and some animals that are asexual and produce clones of themselves) to fight parasites through genetic variation. this also does not favour incest. along the same lines, people usually pick mates (not australians) with different immune systems precisely for combating disease from different angles. and let me tell you, you wouldn't be here if it were for incest. female chimps usually migrate to other groups exactly for these reasons and to diversify the gene pool. so go marry a gorgeous black woman! but not an albino, especially if she is your sister.

Oikoman

Its worth noting that populations or species of animals that regularly engage in incestuous reproduction tend to not to have the same problems humans do (recessive deleterious genes being expressed) since these lethal or deliterious gene combinations will have been selected out of the population. The negative effects of incest on human populations suggests strongly that incest is an abnormal condition in humans, and not as the OP suggests a "fact of life".

LP675

HAhahaha…
I had to read that three times.

I thought at first you were getting down and nasty, busting out an Australian joke. Now I see you were not insinuating Australians were incestuous, but clarifying the sense in which you were using the word “mates�.