Mitochondrial Eve [was: IE, AA, Nostratic, etc.]

As the name of Mitochondrial Eve has been taken in vain, let me briefly debunk the mythical aspect of that entity (others have done so before, but the ghost of Eve goes marching on).

Let’s consider H, the set of all the human beings who are alive at the moment. Each of us has one and only one mother. Those of us who have brothers and/or sisters share their mother with them. Some of our mothers are still alive, so they also belong to H. As you probably know, all (in fact, NEARLY all, but let’s ignore this nuance) our mitochondrial DNA is inherited via matrilineal descent. This means that if you want to trace back the history of anyone’s mitochondrial genes, you have to consider that person mother, mother’s mother, etc.

Let’s therefore define G1 (G is short for *gWenax-) as the set of all the women who are mothers of someone in H, but who don’t themselves belong to H. This definition guarantees that none of them is alive at present, but that all their mitochondrial DNA lives on in us; what’s more, all extant mitochondrial DNA is inherited from G1, since everyone of us is a child, a daughter’s child, or a daughter’s daughter’s child, etc., of a woman who belongs to G1. (ARE YOU STILLWITH ME?) It’s easy to see why G1 must be smaller than H.

Now G2 is the set of all the women who are mothers of someone in G1, but don’t themselves belong to G1. All out mitochondrial DNA is inherited from G2 via G1, G1 and G2 don’t overlap, and G2 is certainly smaller than G1.

If we proceed in this fashion, we can define G3 which can’t be larger than G2, G4 which can’t be larger than G4, etc. The sets Gn get smaller and smaller as n increases, and G(n+1) always contains all the mitochondrial genes to be inherited by Gn. Will the size of Gn ever reduce to 1? It should, except in the extremely unlikely case that the size of Gn, G(n+1), G(n+2), etc., should remain forever greater than 1 but constant.

The sole member of the set GN such that GN has one element but G(N-1) is larger than GN is called Mitochondrial Eve. There’s nothing special about her; her existence has been deduced mathematically and she’s the end result of our selection procedure. She’s the most recent female from whom all the present-day human mitochondrial DNA derives; the reasoning above proves (well, almost proves in this simplified presentation, but the gaps could easily be filled) that such a female existed once upon a time, but without examining actual empirical evidence we can’t even know if she herself was human or pre-human.

BTW, Eve also had a mother who had a mother and so on, which means that, for any m > N, G(m) remains equal to 1 until we reach the very remote age of the first sexually reproducing eukaryotic organisms.

Any hypothesis asserting that Mitochondrial Eve lived so-and-so many years ago may be more or less credible (the methods of estimating the number of generations between her and us have stirred much scholarly debate), but tells us NOTHING about the total size of the human population at that time. Eve could have been one of many thousand women living at the same time. Many of her female contemporaries are also our ancestresses, but (by pure chance) the DNA we have inherited from them is non-mitochondrial. Remember that each of us has four great-grandmothers whose contribution to our genetic makeup is virtually equal, but our mitochondrial genes come from only one of them. Let me add that she need not be the one whose language we have inherited.

In short, the classical version of the Mitochondrial Eve Hypothesis (which claims that Eve lived in Africa and was a specimen of Homo sapiens) may or may not be correct, but in either event has no bearing whatsoever on the problem of language mono- or polygenesis.

It’s OT but interesting, I hope.

Piotr