gordonr at cc.UManitoba.CA
Wed May 3 12:27:46 EST 1995
On 3 May 1995, Keith Robison wrote:
> I would argue:
> 1) In most of the cases studied, the work on bacterial
> evolution which _seems_ to be adaptive (Lamarckian) is
> fully Darwinian (random, undirected mutation + selection).
> 2) That the distinction between Lamarckian and Darwinian
> evolution becomes less distinct in unicellular organisms,
> because there is no division between soma and germline.
The same confusion reigns at the multicellular level, where it takes the
form of "developmental constraints" and whether or not evolution is
"directed". In physics, we can have "directed" motion due to momentum,
which no one nowadays embues with mystical qualities. In other words,
given a large enough (sufficiently complex) system, its motion
(evolution) is reasonably predictable, at least for a while. What the
bacteria have done is not random, because hot spots for mutation are
activated. In the radiation of multicellular organisms, similar phenomena
may be occurring. The part of the genome that does not change we perceive
as being subject to "developmental constraints", while the part that does
gives the appearance of "anticipating" future needs, though, of course,
over the dead bodies of many unsuccessful individuals (i.e., by
selection). Thus we get orthogenesis, directed evolution, Cope's Law,
progressive evolution, etc., all of which smack of Lamarckianism.
Thus the above argument needs some work.
-Dick Gordon, U. Manitoba[May3,95]
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