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Re: the tonight show




Charles,
Well, I for one agree with you, and it was clear to me that you were talking about taxa and not people. And I wasn't going to discuss this topic further, but George's comment below needs to be challenged.
If "A" is the common ancestor of Bacterium "D" and Homo sapiens ("C"), then "A" is clearly a more primitive bacterium. Obviously A and D (both bacteria) are far more closely related to one another than either of them is to Homo sapiens, and there would an enormously long series of B's (intermediate forms) separating Bacterium A from Homo sapiens.
This extreme example makes very clear how deceptive cladistic reasoning can be, especially when trying to equate "relatedness" with cladistic "relationship". This is not very apparent when you have only one or two intermediates, but throw in a whole bunch of them and the example Charles gave should be clear to all.
------Ken
P.S. Anyone uncomfortable with using bacteria in the above analogy can substitute choanoflagellates (or even fish) instead. It works even better, since you wouldn't have the eukaryotic chimaera to complicate the analogy.
*******************************************************
From: Dinogeorge@aol.com
Reply-To: Dinogeorge@aol.com
To: dinosaur@usc.edu
Subject: Re: the tonight show
Date: Wed, 10 Jan 2001 14:11:03 EST

In a message dated 1/9/01 9:48:25 PM EST, wuckus@ecol.net writes:

<< Is this correct? Consider four creatures, A, B, C, and D.

 A --> B --> C

 and

 A --> D

 Both C and D have A as their most recent common ancestor, but because B
 interceded, C may, or may not, be more closely related to A than D.

 Or, no? >>

No. As species, B, C, D are all descendants of A and thus equally closely
related to A. We're talking about taxa here, and the analogy with people in a
family tree breaks down.
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