A problem with our attempted explanations here is that we've been, at least to some extnent, polluting the real question of "what/who is MRCA(Eve)" with attempts to explain why or how or who gives a shit about whether .... etc.

MRCA(Eve) is a mathematically defined concept that's interesting because we can prove mathematically that "the thing called MRCA(Eve) must exist" and we can say things, with real mathematical certainty about "the thing called MRCA(Eve)".

The key is to get the definition straight, so that we know what we're talking about, before speculating about circumstances and conditions, etc.

In this thread, at:

18 Oct 06 - 06:05 PM ( (local link to page 3 if you're loading by the page) you'll find a link:

What, if anything, is a Mitochondrial Eve?

The explanation there is much more thorough than I can re-create and give easily here.

Note the comment at that link, that the MRCA(Eve) is:

"… the most-recent common ancestor of all humans alive on Earth today with respect to matrilineal descent. That may seem like a mouthful, but without even a single one of those qualifying phrases, any description or discussion of the ME reduces to a lot of nonsense."

In other words, if you do not observe any one of the conditions of the definition, you may have something that's of interest to somebody – perhaps even to you yourself – but you are not talking about MRCA(Eve). The same happens if you try to add anything else to the definition.

Look at the definition carefully:

The (most recent)¹ (common ancester)² of (all humans alive on earth today)³ (with respect to matrilineal descent)⁴.

There's also some lesser discussion of MRCA(Adam) at the same link, but the female line is better defined and easier to analyse, so the mathematicians assert that it's more important and spend most of their time and effort on the matrilineal line.

John