Re: Date for Last Common Ancestor?

12 Aug 1996 11:18:31 -0400

"Let S_1 be the set of all people whom are alive today. Let S_2 be the
set of mothers of the members of S_1. In general, let S_k be the set
of mothers of S_k-1. The size of these sets is nondecreasing (S_k <=
S_k-1), because everyone has only one mother, but some mothers have
more than one child. When the size of the set reaches 1 then we have
arrived at the mitochondrial Eve.

Steve Barnard"

This does not prove that the cardinality of the sequence of sets {S_k}
coverges to one. To establish the existence of a "Last Common Ancestor"by
logical means only will require quite a lot more than you have supplied,
starting with a clear definition of what is the "Last Common Ancestor" for
a species.