I don't think so. If all humans have a common ancestor, then the reciprocal
relation is only that the one common ancestor has all humans as his or her
descendants. You can't infer anything about all ancestors from the original
statement. (X is an ancestor of Y iff X appears in Y's genetic lineage.)
-- David McFadzean david@lucifer.com Memetic Engineer http://www.lucifer.com/~david/ Church of Virus http://www.lucifer.com/virus/