|Hello,Today in science we were learning about
Darwin, evolution, and artificial/natural
selection. I was wondering why there aren't
sub-species of human like there are types of geese
and breeds of dog.
There are not sub-species of humans because we
have not had enough time to evolve enough genetic
differences. On different continents on earth,
people have evolved slightly different
characteristics from each other due to selection
and genetic drift. Different races of people have
different skin color, others a greater ability to
store fats (eskimos), others have evolved
different blood types (sickle cell), etc.,
however, this differences are not big enough to
classify us as different subspecies.
Naturally, subspecies evolve very slowly. Humans
have only had 100,000 years to evolve differences
from each other, which has not been enough time
and I doubt humans will ever evolve subspecies
because there is not global mixing of genes
through inter-racial partnerships.
Subspecies can be created in animals in less than
100,000 years through artificial selection, which
is what humans have done with domestic animals.
Because humans can been able to choose genetic
characteristics and animals have a relatively
short time to reproduction, we could get very
genetically different breeds in a matter of tens
There are - the different ethnic groups of
humans qualify as subspecies. There used to be
more subspecies, but they've become extinct.
That said, humans are remarkably uniform in
their variety; most subspecies are more different
from each-other than the human subspecies are. The
reason for this is not completely known - although
in the case of dogs, dogs were bred artificially,
so their breeds are much more different than what
you get in nature.
Actually, breeds of dogs are all the same
species (and the same goes for cats)! If they were
not the same species, they would not be able to
produce "viable offspring," or offspring that
could also reproduce. So if you want to carry the
analogy across to us, we do kind of have "breeds"
in the sense that people from different parts of
the world have different "phenotypes" (physical
characteristics). I hope this helps!
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