[Taxacom] Evolution of human-ape relationships remains open...

[Kenneth Kinman]

Hi Richard,
         After rereading what I wrote, I don't blame you for being
flummoxed.  I was too tired last night, and I muddled that first
paragraph.  Actually, I don't think the orangutan line and the hominid
line have an immediate common ancestor.  Rather, the orangutan line had
an immediate common ancestor with the hominid-African ape line.  Then
there would have been an extinct stem lineage between that common
ancestor and the immediate common ancestor of the hominid-African ape
clade.       
       I still think there is insufficient information available to
decide about the interrelationships within the hominid-African ape clade
itself.  If the authors of that gorilla genome paper are correct
(concluding that chimps and gorillas developed their complex genomic
structures convergently), then my hypothesis that chimps and gorillas
form an exclusive clade (to the exclusion of the hominid line) would be
in big trouble.  However, their conclusion might not be valid
(especially if it is based on the assumption that chimps and hominids
clade together exclusively).                  
      Anyway, if strong evidence of an exclusive chimp-gorilla clade is
found, we will then have to figure out why there was all of that
misleading information that appeared to support an exclusive
chimp-hominid clade.  I suspect that it would have been caused (at least
in part) by some hybridization between early hominids and early chimps,
perhaps followed by a population bottleneck (as in the case of a
bottleneck occuring after polar bears and brown bears hybridized in or
near Ireland).  
       ---------Ken Kinman               
------------------------------------------------------
Richard Zander wrote:  
    First, you do answer directly and posit a common ancestor of man and
orangutans similar to humans and orangutans. But you imply that it is
not a direct common ancestor. In which case I am flummoxed. In the past,
in answering the same question, you indicated that there was
insufficient information to decide what the ancestor of humans looked
like prior to the split to chimps, which is fine. No adduction possible.