Marriages - What do you think?

[grayfalcon89]

Recently (actually today about 5 minute ago), I read an article from Discover August 2005.

 

Basically, the article suggested that the intermarriage, or marriage between cousins, isn't exactly what most people think. Like it's explaining no one really "like" intermarriage but from genetics, the prejudice that people have on intermarriage such as "if you marry your cousin, your baby will have 9 heads" are not true.

 

Maybe that example is obviously wrong since it's probably impossible to have a baby with 9 heads.

 

But my point is, what do you think about the intermarriage? I personally go against it but like after reading this article, there isn't necessarily any wrong with it. I mean, before we had car and other mobiles that helped us on the movement, most people say the family has last name of AHHHHHH, would marry with AHHHHHH because AHHHHHHH is the only family member you can find.

 

Any respond is great. It would be more better if we can get into some based-on fact discussions.

[syntax252]

In my part of Michigan, there are many Amish people. This is a problem among the Amish.

 

Their church leaders take pains to try to bring in "new blood" but over the years the Amish are all pretty much related in some fashion.

 

I do not know for a fact, but I don't think that retardation or other birth defects are any higher among the Amish that among us "English" as they refer to us.

[1veedo]

In many cultures, including eastern, where intermarige is not only considered normal but is encuraged.

[Cadmus]

But my point is, what do you think about the intermarriage?

A large number of societies have developed taboos against marriage to closely related relatives. Exogamy has been practiced by most societies, I believe. The science that I read decades ago gave scientific explanations of why this is a good thing. I don't know if your article is correct or not.

[Cadmus]

In many cultures, including eastern, where intermarige is not only considered normal but is encuraged.

What cultures, and particularly what eastern cultures?

[Coral Rhedd]

Cousins mating. Oh dear. That would be like going to the dogs.

 

http://www.bullmarketfrogs.com/pages/generalarticles/caninebreedingprograms.htm

 

Where or not marrying one's cousin would be bad would depend upon whether both cousins were healthy specimens in the first place. When good characteristics are bred for, the result is improvement. Alas, human beings are not so deliberate.

[Nevermore]

The problem with incest is that mutations are more likely to occure. Consider the following: In order for a mutation to emerge in a child, both parents must be carriers. 2 cousins, or other relations are much more likely to share the same mutations, because they have numerous common ancesters. Thusly, Incestually conceived children are much more likely to be deformed.

[Coral Rhedd]

But then again people may simply not want to mate with relatives. Seems they don't pass the smell test:

 

http://www.mc.maricopa.edu/dept/d10/asb/anthro2003/origins/scent.html

[Mokele]

Actually, it's not mutations. Mutations occur no more rapidly in incestuous populations than normal ones.

 

The problem is lack of heterozygosity. There are *lots* of mutations in any gene pool, but most are safely hidden in heterozygous form.

 

Imagine a parent is heterozygous for a trait. She has a 50% chance of passing on that allele to each of here 2 offspring. Now, say those two mate. Each of them have a 50% chance of passing that allele on to *their* offspring. The result is that there's a 1/16th chance that the offspring will be homozygous for that allele.

 

That may not sound like much (and it goes down as the inbreeding pairs become more distantly related), but most mutations exist at such low frequencies that a 1/16th probability is a *huge* increase. Now apply that to *every* mating in a population.

 

The result is that individuals become more and more likely to be homozygous at any given locus of their genome. Eventually, there's only 1 allele of any given gene in the population, and that allele became fixed by chance, not selection, so it's usually bad. Controlled studies on birds and insects have shown that mean fitness declines in even slightly inbred population.

 

So it's not that the mutations happen more often, but that they are homozygous more often, so you notice them more.

 

Mokele

[1veedo]

What cultures, and particularly what eastern cultures?

I meant Western!!

 

Like, Asia.

 

The very first Sumarian culture saw incest as "normal."

 

So did early China (I think even modern). I'm not sure exactally which, but alot of cultures in Asia accept it.

[Aardvark]

The very first Sumarian culture saw incest as "normal."

 

So did early China (I think even modern). I'm not sure exactally which' date=' but alot of cultures in Asia accept it.[/quote']

 

You are wrong about that, the Sumerians had laws that made incest a capital offence.

 

The incest taboo is universal amongst all human cultures for very good biological reasons.

[Aardvark]

I do not know for a fact, but I don't think that retardation or other birth defects are any higher among the Amish that among us "English" as they refer to us.

 

The Amish suffer a relatively high rate of minor birth defects such as polydactyly (extra fingers and toes) and congential heart disease.

[1veedo]

Ok, I tried to find a site with a list of cultures that had it, but this is all I could find (except references to "some culturs accepted it."

The term incest refers to sexual contact between close blood relatives for whom such behavior is forbidden by law, custom or religion. Taboos against incest have been found in virtually all human societies, although some exceptions have been documented, including the Incan society and the societies of ancient Iran and Ancient Egypt.

[Aardvark]

Ok, I tried to find a site with a list of cultures that had it, but this is all I could find (except references to "some culturs accepted it."

 

All cultures and societies have incest taboos.

 

When cultures such as Ancient Egypt are mentioned as exceptions even those cultures had strong taboos in this regard, it being only the single example of the ruling Pharoah who was made an exception for religious reasons. Everyone else would have seen incest as something to seriously avoid.

 

For some reason people occassionally raise the question of whether the incest taboo is biological or cultural, which is odd as it is a clear matter of hard fact that incest is genetically harmful. It seems to be a hangover from cultural relativists who get upset at seeing biology knock down their concepts and so try tilting at the wind mills once again.

[ydoaPs]

so, that explains Kentucky...

[5614]

Personally I wouldn't intermarry but I don't really have anything against people who do.

[Auburngirl05]

I read that article last fall, and if I remember correctly it gave an example of some lines that are traditionally "inbred" to some degree that have virtually no major defects, and also mentioned some cases of malformations etc in other lines....it all goes back to what Mokele said about heterozygosity, the risk of defects depends on the gene pool you have to start off with, some gene pools are "deeper" than others and could stand up better to intermarriage.

 

As a side note, (and the link Coral Rhedd provided talks about this) with some breeds of dogs (German Shepherds are an example) "line breeding' to a certain degree is valued, it involves the same ancestor appearing on both sides of a dog's pedigree (paternal and maternal sides), it's done purposely by professional breeders, and is considered distinct from careless inbreeding.

[Auburngirl05]

I just pulled up this page to explain what I was talking about, it's titled "Linebreeding vs. Inbreeding, The Importance of Breeding for Variety"

http://www.compusire.com/linebreedinbreed.html

 

and here is another good explanatory article:

http://bowlingsite.mcf.com/Genetics/Inbreeding.html

[JohnB]

"line breeding' to a certain degree is valued, it involves the same ancestor appearing on both sides of a dog's pedigree (paternal and maternal sides), it's done purposely by professional breeders, and is considered distinct from careless inbreeding.

Saying the animal is "line bred" also increases it's value. If you really looked at the breeding, I'm sure you would find many dogs that must have lived to around 30. Same thing happens with Greyhounds.

 

Concerning humans, I think the prohibition goes much further back than history records.

 

Logic tells us that long ago there was only one tribe of humans. This tribe would have split, with some moving off to the next valley (or wherever). As the tribes split further and spread out, they would have met at times to exchange news and brides. (The forerunner of "Spring Fairs" and the like.)

 

Over time it would have been noticed that those families (tribes) that did not participate in the gatherings became less "desirable" as mates. This would give rise to pressure for someone to mate outside their immediate tribe. After a few thousand years this tendency would move from observed neccessity to the status of moral and religious lore.

 

A similar thing can be noticed with circumcision. A practice that was invented in response to the observed damage caused to the male in a dry and sandy or dusty climate. Notice that it was not widely practiced in cooler, wetter climates.