John, here is how I came at the question. I started a genealogical chart with only MRCA(Adam) on it. I then add his children and their children all the way down to today. Every living person is on this chart. Every living person can trace their ancestry back to MRCA(Adam). If you go back just one generation then you find Adam's mother. Therefore every living person can also trace their ancestry to her. The genders of Adam's children don't matter in this.

If all of Adam's children had the same mother then MRCA(Adam) and MRCA(Eve) would be in the same generation but there is no way to know whether this is true or not. But if not, then since we do know that MRCA(Adam) only had one mother she MUST be the MRCA(Eve).

I am not looking at the genetics of this. Taking the question from my premise the genetics can be used to approximate a date for when MCRA(Adam) and MRCA(Eve) lived. Since the geneticists are asking two different questions (one for Adam and one for Eve) it is possible to come up with very different answers.

I think what the geneticists are doing is very worthwhile and can yield valuable insights. In my view, they are coming at the question from a different side than I am. As far as I can see the MRCA(Adam) and the MRCA(Eve) can not be more than a generation apart. It is just not physically possible.

Please look at the question from my perspective and let me know if you see a flaw in my logic. Maybe I am missing something but I (obviously) don't think so.

BTW, the caps and bolds are fine with me. Creating emphasis can be a tricky business.