Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!bbn!rochester!PT.CS.CMU.EDU!K.GP.CS.CMU.EDU!lindsay
From: lindsay@K.GP.CS.CMU.EDU (Donald Lindsay)
Newsgroups: sci.misc,sci.bio,soc.women
Subject: Re: Universal Common Female Ancestor
Message-ID: <178@PT.CS.CMU.EDU>
Date: Thu, 15-Oct-87 12:46:02 EDT
Article-I.D.: PT.178
Posted: Thu Oct 15 12:46:02 1987
Date-Received: Sat, 17-Oct-87 08:47:26 EDT
References: <2545@sigi.Colorado.EDU> <2047@arthur.cs.purdue.edu> <2567@sigi.Colorado.EDU>
Sender: netnews@PT.CS.CMU.EDU
Organization: Carnegie-Mellon University, CS/RI
Lines: 23
Xref: mnetor sci.misc:563 sci.bio:751 soc.women:7782

In article <2567@sigi.Colorado.EDU> pell@boulder.Colorado.EDU (Anthony
Pelletier) writes:
>The notion of a group of organisms going off into a secluded area and
>evolving together into a new species seems absurd to me.  I can buy that
>selection on all of them is the same, but the random element of evolution,
>mutation, cannot possibly occur in them all.

No no no. The "punctuated equilibrium" theory says that a subgroup becomes
genetically different. It doesn't say that they all simultaneously mutate,
no doubt while touching a black monolith.

One creature, born with a nonfatal mutation, tries to pass the change on
to his available genetic pool. If the pool is small, then there is a good
chance the change can become universal, even if it has no value (or even
negative value) simply by the probabilities of gene pools.

If a group of creatures becomes cut off from the main pool, then for the
duration, they constitute a small pool. Hence, the laws of chance begin to
dabble with them, and they MAY diverge in a useful direction.  When-and-if
the isolation is over, they may replace the parent species, or merge back
into it, or coexist as a new species. That's the theory.
-- 
	Don		lindsay@k.gp.cs.cmu.edu    CMU Computer Science