On 27/07/2006, at 11:43 AM, [EMAIL PROTECTED] wrote:
One of the problems with your mode is thinking is the "by
definition" part.
This is way we used to think about species before Darwin.
...and a long way after. The Biological Species Concept was developed
through the mid-1900s, with much of the argument in the 50s. Of
course, gene sequencing in the 80s and on has thrown more mud in the
waters, as if it needed it... The concept of "kinds" was pretty
prevalent right into the 1900s, but it no longer survives in science
as a useful concept.
They were thought of
as having some essential essence unique to them. However we now we
define
species in a variety of functional ways. The definition I gave
(interbreding
populations) was developed by Dobninsky and Mahr. (ok I probably
spelled these
names wrong).
Dobzhansky and Mayr, but I got who you meant. Good call. :-) Mayr
only died last year, by the way, just short of his 101st birthday. He
saw quite a few changes in the field of biology during his loooooong
career.
Anyway, the Biological Species Concept, as with every single other
way of defining species, has weaknesses. With this one, it's that it
assumes sexual reproduction, so asexual organisms are hard to
classify using it. Ultimately, in defining species, biologists use a
combination of the various methods, tailored to the situation.
Whatever definition one uses species are real but they are
natural things with blurry margins not philosophical things (with
distinct
essences). So the something else that HeLA cells would be would
still be human in
some ways and maybe not human in others. In some circumstances
they would be
separate species and in other circumstances they would not be.
Indeed - what way you look at them defines what they are, not what
you call them. Names are just labels, they're not what things are.
Living things are named and renamed, classified, shuffled. That's
science - as we get new information, we refine the knowledge base.
Names impose borders where there really aren't any. There may be
gaps, but there are no sharp lines.
Charlie
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