>> After all, for example, genetically, I believe, various
groups are susceptible to different illnesses. I have been
told that such resistances are enough to classify
micro-organisms, if not higher creatures. Could this
be a basis of further breakdown of our species?<<
>..."Human genome findings practically erase race as a
biological factor"<.
Terms such as race and group need defined, as well as
the type of suceptibility in question. Race is used
biologically as an informal taxonomic term, less than a
subspecies; however, differences between such races are
still generally greater than between modern human
populations. In popular usage, race for humans refers to
very broad ethnic categories, roughly corresponding to
African versus Asian versus European origin. The
broadness of the groups, intragroup variation, and
interbreeding are such as to make genetic or
immunological differences rare at this level.
Smaller subgroups, especially isolated populations that
are relatively inbred, often have distinctive genetic markers,
including diseases. For example, sickle-cell anemia is
characteristic of certain African populations. As this reflects
a single DNA base change, calling them a separate
species would be ridiculous.
Suceptibility to infectious diseases generally reflects
exposure rather than genetic heritage, due to the workings
of our immune system. Thus, the ravaging of New World
populations by diseases from European and African
immigrants reflects the total lack of prior exposure and
acquired immunity rather than a real genetic difference.
Differences in environment and diet also affect disease
occurrence, but these may be culturally or geographically
linked to ethnicity. Again, this is not valid to distinguish
species.
All species contain some genetic variation, and the
difference between generally recognized species varies.
Genetically, we are extremely similar to chimps, yet
morphologically we are very different, and the pattern of
gene activity in the development of the brain is also very
different. The commonalities, including the apparently free
interchange of genes, among human populations argues
that we are a single species. H.G. Wells, in The Time
Machine, envisioned social separation as eventually
producing separate species, and theoretically this is
possible. We seem to be tending towards greater mixing
rather than differentiation at present, however.
Dr. David Campbell
Old Seashells
46860 Hilton Dr #1113
Lexington Park MD 20653 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand
Exalted Periwinkle of the Mystic Order of Whelks-P.G.
Wodehouse, Romance at Droigate Spa
This archive was generated by hypermail 2b29 : Fri Feb 22 2002 - 16:29:08 EST