I can’t find cites (maybe someone can help), but I remember seeing something on the History channel where the human race got its start primarily through close-kin inbreeding. When and why did this attitude change?
I trace it to the first season of the Jerry Springer show.
Sometime in the last 2 million years, I would guess.
If you remember from high school biology, there are dominant and recessive genes. Two close relatives with similar DNA structures are much more likely to pass on recessive genes to their offspring resulting in fucked up kids.
That’s why you need to mix things up a bit.
From a genetic standpoint, close inbreeding greatly increases the chance that any harmful recessive traits will be expressed. Most species naturally tend to avoid it.
I’ll try to find a cite to back this up but I seem to remember that in-breeding is nowhere near as dangerous as you would be led to believe and that even if you had a child with your sibling, there would only be an 8% increase in the likelihood of a serious birth defect.
My guess as to when this viewpoint came to be so popular was in response to the Royal Families of Europe, which had a centuries long habit of marrying inside their bloodline only and, no so coincidentally, a history of mental instability and genetic defects. (an eight percent rise in the likelihood of a disease multiplied over several generations starts to approach a hundred pretty quckly.)
Also, I think it was not uncommon as late as the mid 1800s in the general population, at least in America. Didn’t Poe marry his niece publicly?
Who gets on with their siblings well enough? 
The incest taboo is pretty class-specific. The very rich and very poor have never felt particularly bound by it (Source: Alan Moore’s copious notes to From Hell).
The recent glurge (as linked to above) that is pro-incest is stupid. First of all, they focus on absolute increases in defects rather than relative. I.e., doubling a small chance is really quite a big increase, not a small one. Secondly, they only mention one-time such marriages. But if there were no laws, the children of incest would marry each other, etc. and the odds really start to skyrocket.
The flaws in logic in such “let’s change the laws” glurge is so glaring, that one has to wonder what’s going on inside these people’s brains.
If we all came from one “tribe” with hundreds (?) of generations of close-kin inbreeding, why aren’t we a bunch of mutants today?
It all depends on how many harmful recessive genes are in the population to begin with. Inbreeding won’t create new harmful genes - it will simply increase the chance that they’ll be expressed. If you had a population that was completely free of recessive defects (very highly unlikely in human populations) then inbreeding wouldn’t be a problem at all.
Maybe we are?
I think the real tabu is on having sex with a direct relation, ie brother, sister, mother, or father. The idea of incest with a cousin though, is much more open to speculation.
Inbreeding can cut two ways. It creates more individuals who express deadly recessive genes. Which is bad for the people who get them, but not a terrible thing for the population, since it wipes out deadly recessive genes faster by stacking them two-by-two in individuals who won’t survive to pass them on. Inbreeding will also help any benefial mutations that come along to stay, and potentially increase, in the population, rather than getting filtered out in the genetic noise of a more diverse breeding strategy.
Some might say we are a bunch of mutants. Back when all this in-breeding was going on, we probably looked a little like this.
George W. Bush is in office. Meanwhile, gas prices are the highest they’ve ever been, but people are still buying SUVs. On the other side of the planet, Muslims are killing Muslims because the Muslims were standing between the homicidal Muslims and some Americans.
Tell me we ain’t just as dumb as a bach’sa rocks.
¯* We are family
I got all my sisters with me *¯
Us regular-hairy-white guys were leaving a Korean museum which had displays of early man. A kid stared at us and asked if we were cave men.
Explanation: Koreans have much less body hair than white guys. We looked like huge monkeys to that kid.
this has nothing to do with the subject, but I thought it was funny.
Various stats of population do show that we are healthier, smarter, etc. than people a couple hundred years ago.
Nutrition, medical care, etc. plays a role of course. But you have to figure that outbreeding plays a big role.
As a gardener, I am well aware of “hybrid vigor”. I.e., the best plants tend to come from disimilar parents. (The exact opposite of racist bigotry thought, of course.)
We were more defective back then than we are now. This is not a bad thing.
I’d like to see some evidence that the human race ‘got it’s start’ from inbreeding. The History Channel does not cut it.
There have been several bottlenecks in human history that probably led to enforced inbreeding and this is reflected in the genetic homogeneity found in humans today. All humans currently on the planet are more closely related than two tribes of chimpanzees living side by side. But that is NOT the same as saying that we got our start from inbreeding. It just means that we managed to survive despite inbreeding. Humans were more abundant and more successful before these population crashes and enforced inbreeding than they were immediately afterwards. That incest was forced on people isn’t evidence that incest is a good thing or that it contributed to the success of our species.
Inbreeeding, except in special cases, is a near universal taboo. It did not become popularised in response to inbreeding in royal families. The most primitive HG societies have strict laws to guard against incest by determining who can marry whom so it’s a safe bet that incest has been a taboo since our species learned to talk and probably earlier.
In other great apes the standard practice is for all females to leave their own band as soon as possible after they reach sexual maturity and join another band. That process acts as a natural safeguard against incest by ensuring that daughters can never mate with their own siblings or fathers. Within the human population the same basic instinct for daughters to leave and join their husband’s family still exists, however the highly nomadic nature of our species and our immediate precursors makes this problematic. For most of our history humans existed as independent bands of 5-10 individuals that only made infrequent contact with other bands perhaps less than once every 6 months. A young woman could not very well be expected to walk off into the wilderness as soon as she began menstruating in the hopes that she would stumble across another unrelated group that could be anywhere. More importantly the woman needed to know that there was willing mate available in the other band. Those restrictions meant that humans ran a very real risk of incest if strict ties were not placed on intermarriage with relatives.
There’s no way of telling how far back the incest taboo goes, but 100, 000 years or more seems plausible.