Finally,although it is impossible to prove a negative, assuming no bottleneck ~200kya and that L0 mtDNA represents Homo sapiens, how likely is it that 1) a single L0 individual populated all Homo sapiens on the globe both living and deceased?
Sorry for jumping in (and sfs is best qualified to answer the detailed genetic questions), but it seems there is a simple confusion between a bottleneck (where the whole population is reduced to smaller number of individuals), vs a mitochondrial line. These are very different. Everyone could be descended from a single female (L0), who lived in a population of a half million individuals at the time, with no bottleneck ever happening.
To understand this, remember that anyone - even the neighbor of the L0 woman - will eventually be the ancestor of the whole human race, as long as they have a few kids and grandkids. In the case of the neighbor of the L0 woman, she too is the ancestor of everyone, even though exactly zero people have her mt. Mt lines die out, while they still have lots of descendants from other mothers. If that doesn't make sense, then ask and we'll explain it more. Regardless of mt survival, most people in ancient populations are the ancestors of everyone alive today.
Let's use an example. Consider any normal person from a long time ago, say, Pharaoh Ramesses II. He ruled around 1260 BC. He had a wife (Nefertari), and kids. Kids will have kids, and since all their descendants will be descended from Ramesses, the number will grow (you can also see this by the fact that Thomas Jefferson already had thousands of descendants after just 200 years, or the fact that there are today many millions of people descended from the few dozen on the Mayflower).
So by 1000 BC Ramesses will have thousands of descendants, and simple math shows that by 800 BC his descendants will surpass the population of Egypt at the time. Of course, many of those will be double or triple descendants, but the upshot is that by then most people in Egypt then will be his descendant. Some of those people will live near the borders, or will have migrated over those centuries, so will be in neighboring countries (Assyria, Babylon, etc.) They too will have kids, and the same spread will happen, so by 600 BC a good chunk of the populations in those areas will be descended from them, and by 400 BC, most will be. The same goes for Asia Minor (Turkey), Greece and Italy by around 400 AD, and into Europe by 600 AD.
Continuing on, most of Southern Europe would be descended from Ramesses by 1000 AD (along with some of Northern Europe) and then most of Northern Europe by 1400 AD, and practically all by 1800 AD. Notice that you can do the same thing with most anyone from Ramesses time who had at least a few kids. You could also start in, say, Sweden and work south, or whatever, and still get a similar result.
So, being of mostly French and German Ancestry, I'm descended from Ramesses, as you likely are (unless you are not European, Middle Eastern or North African).
All that happened without there ever being a population bottleneck. Ramesses & Nefertari were never the only ones on earth, yet, withing a few millenia, everyone on earth will be descended from them. We agree that Ramesses and Nefertari, like all humans, evolved from earlier apes.
Now, imagine a population of hominids in Africa. At some point, say, a million years ago, designate two as "Adam & Eve". From a Catholic standpoint, God gives these two the first souls - they are the first "full humans", even though they are very similar in most respects to everyone else at the time, and so their children can interbreed with the others. All their descendants also receive souls, and hence are also "fully human".
Now the same thing we saw with Ramesses happens, and within a few thousands years (say, by 960,000 years ago) everyone on earth is descended from them, and is fully human, and there never was a population bottleneck.
2) The descendants of other L0 mothers existing concurrently (e.g. A sister, female-lineage cousins with a shared maternal grandmother, etc) didn't contribute to the mtDNA pool?
Whoa - careful here. An "mt pool" is very, very different from the autosomal gene pool that is usually referred to. That's because the autosomal DNA is constantly mixed through recombination, so individual genes can go anywhere. That's the opposite of mt, where someone is either fully or not at all, part of an mt line. Mt doesn't mix. Make sense?
mtEve=ensouled Biblical Eve.
I wouldn't equate mtEve with ensouled Biblical Eve. The two are unrelated ideas, and the naming of L0 "eve" I think was scientifically a very bad idea (and irresponsible to boot). Names chosen in science should help clarify, not sow confusion. Also, remember that Mt Eve and Y Adam lived thousands of years apart, with one of them mating with the distant descendants of the other.
If the OP simply means to say that at some time in the past 200kya, two special indivuals eventually genetically (autosomally and perhaps Y chr. also) replaced other Homo sapiens, .
No, no replacing is needed. Just interbreeding. The pharaoh example above shows that replacement is not only not needed, but is misleading.
This explanation has serious theological difficulties.
The idea of a population of transitional apes becoming human, with one pair designated as Adam and Eve seems fine theologically to me. Maybe discuss what difficulties there could be with this or that explanation?
in Christ-
Papias
