CaptainOfOuterSpace

Inbreeding exists because of evolution. That's precisely why it's being used to make fun of Christianity.
This is a quote by Paul Ashton (the producer of the documentary on this subject) from an interview:

demoninho

Coz we got natural selection. Actually in small population the frequency of bad genes dimishes very rapidly. Actually a friend of mine did his PhD on this subject maybe I can find his thesis somewhere. Anyway it's not really a BC&H matter.

Oolon Colluphid

Yup. Because the problem is obvious, and so believers are stupid or ignorant. Hence, easy targets for humour.
It does, for very small populations. That's why zoos go to great lengths in their endangered species breeding programmes to ensure that the animals they breed are not closely related -- a problem when so many zoo animals are related! Bottlenecks are a serious problem. Cheetahs, for instance, are apparently down to such low numbers that they may not recover. If your population is too small, evolutionarily speaking, you’re probably stuffed.
Oh, ho ho! Perhaps you should avoid subjects with which you are unfamiliar? There having been an ‘African (mitochondrial) Eve’ does not mean that there was just a single female alive and breeding, it just means that of all those alive and breeding, only one has left descendants down the purely female line. See this recent post for an elaboration. In other words, the African Eve idea has nothing to do with bottlenecks.
Nein.
Hogwash.
Start with a basic book on genetics, add in a few pages from the Cambridge Encyclopedia of Human Evolution (try the index), and show me where there was any serious inbreeding.

Oh, and WTF has 70,000 years got to do with it?

TTFN, Oolon

Rational BAC

70,000 years has nothing to do with it. Or maybe it does.

Just thought it was a long time between dates. (pun intended)

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Just wanted a simple explanation for the layman. OK------so Eve was really 250 people? That was never a fewer number at some time in prehistory? 250 people just popped up? Wasn't there maybe 2 or 3 at one time to bring about eventually that 250 with common DNA?

Still seems like at some point there must have been some serious inbreeding.

I really do not want to take a whole course in genetics. If this is way over my head without a lot of book learning, and therefore can't be explained in layman's terms, then just say so. I can live with that.

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Here is my best guess, again from a layman's point of view-----At some point there was an awful lot of inbreeding---sister/brother etc. And those who managed to survive the problems involved --survival of the fittest and all that---became the human race.

Of course the same thing could be said about the Genesis account---only problem being is a lot less time to work with.

Rational BAC

Just to continue this for the heck of it.------

I'm not a Biblical literalist anyway, just curious how Genesis might have played out with a whole bunch of inbreeding similar to what I think must have happened at some point in the evolution theory.

Let's see---There was Adam and Eve and they both lived 100's of years, I believe. So allowing for one birth every couple years maybe, assuming no birth control, Adam and Eve would have been capable of producing 100's of offspring. The Bible just mentions 2 of course. But that didn't mean there weren't 100's more--just omitted to concentrate on the story. And it is most likely that there were 100's born of this union. (unless they just didn't like each other--maybe Adam snored?)

Now you have the minimum of 250 necessary for inbreeding to not be a problem. And even assuming that over 90% of those products of sister/brother intercourse died, that still leaves enough survival of the fittest remaining to form a human race. And assuming that Genesis is correct about living 100's of years, (laughable of course, but just assume it for argument's sake) then the next generation would have really taken off. With each succeeding generation the problem of inbreeding would become less and less.

Rational BAC

Still playing with this one. ----

I would think that the "inbreeding" problem could be easily settled. And using a scientific method. Not using people of course, but using animals.

Has anyone ever tried this to see if it would work as an experiment? -------

Take 2 dogs and breed them. Take their offspring and breed them to see how many survive. Take their offspring, assuming any survived at all, and breed them. And on and on. It would seem like you could easily verify whether inbreeding caused the complete demise of a species or not. And you could duplicate 100 generations fairly quickly --in the case of dogs--. And I assume the results would apply to humans. Why not?

Has anyone ever tried such an experiment just to see what happened?

I mean you can theorize all you want to, but nothing beats empiricism.

Oolon Colluphid

Nope, it’s quite simple really. You get your mitochondrial DNA -- which is what the African Eve thing is about -- only from the female line. You have only the one maternal-only great-great...great-grandmother. But potentially hundreds of ancestors by other routes.

All the mtDNA / Eve business says is that at some point there was a single female ancestor whose mtDNA has survived till now. It makes absolutely no prediction about the size of the population -- population, yeah, as in ‘lots of them’ -- of which she was a member. No bottlenecks required... and so no inbreeding requiring an explanation.
Nope. ‘Eve’ was a single female. It’s just that she wasn’t the only female, just the only one whose mtDNA is still around.
Probably not, because population bottlenecks are a bugger for a species’ survival... because of inbreeding!
Erm, you’ve lost me. We evolved. From Homo erectus, most probably, and before that from something close to ergaster, then habilis or similar, then some flavour of Australopithecine, then maybe Ardipithecus, and so on. And evolution is something that populations do, not individuals. You need breeding populations. Maybe as low at some point as 250, but they were one population branching off from a larger one.

So we’re talking thousands of individuals each generation, right back -- an occasional pinch-point here and there, but never below a sustainable level. Sustainable, that is, from the point of view of inbreeding being a terminal problem!

And only a tiny fraction of those are entirely on the female mtDNA side. That bit of DNA is the only one that ‘African Eve’ refers to: there’s probably a cytochrome c ‘Eve’, a haemoglobin allele ‘Eve’, and an insulin allele ‘Eve’ too. And they will not be the same female, nor even have lived at the same time. Come to think of it, they don’t have to be Eves. There’s probably Adams mixed in. We just use mtDNA because it is only passed on in eggs, not sperm, and so can be more easily traced back.

I admit it is hard to grasp, but have a go at Peez’s explanation that I linked to.

So there never was an ‘Adam’ nor an ‘Eve’, single individuals. It was populations all the way back to the first twitchings of life. And the ‘mtDNA Eve’ term is a pain in the backside, because it is so easily misunderstood.

Cheers, Oolon

Oolon Colluphid

Mods, this is interesting, and may get a fuller response in E/C, don't you think?

Oolon

Oolon Colluphid

I doubt it's been done with dogs -- the generational turnover would in fact be far too slow -- but I'd be surprised if it's not been done with the good ol' fruitfly. Anyone know?

:notworthy :notworthy Couldn't agree more!

Cheers, Oolon

Rational BAC

Well you could duplicate 100 generations in maybe 30 years. Not that slow really.

(Actually I'm lousy at math. Probably more like 40 generations in 30 years.)