[extropy-chat] Human Evolution

[bradbury]

On Wed, Nov 19, 2003 at 4:06pm The Avantguardian <avantguardian2020 at yahoo.com> wrote:

> *I don't know why you can't get to the science abstract.

Both Science and Nature have very strange policies with regard
to viewing abstracts.  Some are simply too old to be present
in the databases, some have a 6-12 month restriction policy
(can't viewed until they are "aged") which is an interesting
contrast to the NY Times which restricts things as they become
"aged".  The thing that I found strange was that I could not
seem to find the abstract in PubMed -- though other abstracts
by the same author/period were present.  [Could be a bad search
strategy on my part.]  The "viewing" strategies are strange
because an abstract that one cannot view on the Science site
one can often find in PubMed.  Educational institutions
often have site subscriptions that allow one to avoid the
details the public has to deal with.

> Some Japanese group apparently claimed he had 47 chromosomes
> while the American cited in the abstract says he has 48.

47 would I think make him a trisomy mutant.
48 would probably make him a non-human primate.
There could of course be very strange variations on this.
(If someone knows otherwise feel free to correct the above
statements).

> I guess reproductive barriers aren't as impassable as I once thought !

You could very well be correct.  There is a significant discussion
as to whether the genome was duplicated once or twice in the
development of higher level animals.  If so there may be sufficient
backup genes (on other chromosomes) that gaining or losing a
chromosome or two over time may not be fatal with respect
to reproduction.

> So I guess in answer to the original question of whether H. erectus and other early hominids were able breed with H. sapiens, I would have to give the answer yes, if the women of whichever species found the men of the other species sexy enough.*

Could be true.  But I would not strongly assert that male mixed
species offspring are always infertile.  That may just be a conclusion
based simply on the examples we are aware of.  It is not like we
have done a great deal of experiments (at least of the published
variety) on this topic.

Robert

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