Re: Hierarchal vs Non-Hierarchal Interfaces to Biological Taxonomy

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sat, 23 Dec 2006 04:23:58 GMT
Message-ID: <yb2jh.36536$cz.537467@ursa-nb00s0.nbnet.nb.ca>

Larry Coon wrote:

> Bob Badour wrote:
>
> Answering several distinct posts at once here...
>
>

>>>>Which opens the floor to: "How many species did you have
>>>>before B went extinct?"

>
> One.

Do you think donkeys and horses are the same species? Or does the reasoning that leads to "one" above lead to "two" for them?

>>>These kinds of questions are always interesting. And they
>>>often lead me to the same conclusion, which is that
>>>the concept being discussed is a construct of the
>>>human mind, and not of the natural world. The
>>>very idea of "species" is an abstraction. A useful
>>>one, but an abstraction nonetheless.

>
> Correct.
>
>

>>Here's an even better one: Suppose a retrovirus comes along that conveys
>>some fitness advantage so that it becomes ubiquitous among a species:
>>ducks for instance. Suppose as well that the virus crosses over from the
>>domesticated duck population into pigs and humans where it too becomes
>>ubiquitous.
>>
>>At that point, humans, ducks and pigs all share a unique recent
>>ancestor. Where does that put us in the taxonomy with ducks and pigs?

>
> Your "at that point, humans, ducks and pigs all share a
> unique recent ancestor" is an incorrect premise. A
> percentage of the human genome (I want to say 8%, but I
> don't remember for sure) came from outside organisms
> like virii, but that doesn't make them our ancestors.

What is the definition of ancestor that excludes them?

> A facinating and related topic is mitochondria. There's
> evidence that it was orignally a separate organism that
> got incorporated into cells in a symbiotic relationship:
> cells provide the sugars that mitochondria need, and
> mitochondira provide the ATP that cells need. So a
> basic feature of eukariotic organisms (animals, plants
> and fungi) was acquired.

Agreed. Are you familiar with Aubrey de Grey's theory of mitochondrial aging? Received on Fri Dec 22 2006 - 22:23:58 CST