From: rh@smds.UUCP (Richard Harter)
Newsgroups: talk.origins
Subject: Re: Great paper
Date: 16 Apr 92 05:41:59 GMT
Distribution: na
Organization: SMDS Inc., Concord, MA

In article <1992Apr14.181502.8971@cbnewsm.cb.att.com>, mls@cbnewsm.cb.att.com (mike.siemon) writes:
> In article <c_xj9bk@lynx.unm.edu>, rsquires@cyclops.eece.unm.edu (Roger Squires)
> writes:

> One needs, rather, a good book on hypothesis testing and experimental
> design.  I'm afraid I don't know the literature and can't recommend one,
> but maybe others here can -- Bill Jeffreys recently posted a citation
> of one which I suspect is mostly directed at the "hard" sciences.

> With regard to biology, the most immediately useful result of thinking
> in terms of null hypotheses is to weed out all the "just so" stories
> that seem to be so insidiously associated with the notion of natural
> selection, at least in the popular mind (and to some extent in lower
> level biology books.)...

It seems to me that scenarios come in two flavors, depending on whether
they leave something to be tested.  The distinguishing characteristic of
the "just so" story is that we are left with no real way to test it.
For a good example of the other side of the coin, consider differentiation
of bird beaks.  There was a Sci Am article recently about the effect of
degree of inclemency of winter seasons on a particular variety of island
birds [Galapagos Finches, if memory serves me correctly.]  The point is
that different types of beaks work best for different kinds of foods.
The hypothesis is that birds with the basic type of beak will differentiate
into varieties with modified beaks in response to the varieties of food
available.

What happens is that the kinds of vegetation available (and seed sizes,
etc) varies a great deal from year to year, depending on the weather.
In years favoring small beakers, the small beakers do well and vice versa.
What also happens, in small beak years, the smaller beaked offspring of
the big beakers do comparatively well compared to their larger beaked
siblings.

My point here is that the "selection on beak size" scenario is, without
supporting data, just a hypothesis.  It certainly sounds plausible, but
without any supporting evidence it is a "just so" story.  For all we know,
in lieu of supporting evidence, some other entirely different explanation
may be correct.  For example, beak size differentiation might be under the
control of a single sequencing gene.  Ah, but there is evidence.  Some
biologists went out and looked and saw what happens and got the data,
so there is confirming evidence for the "selection of beak size" scenario.

Biologists are doing this all of the time.  Chris Colby has posted a
number of examples.  Its part and parcel of science.  You have a hypothesis
about what might have happened.  You ask, "If this is true, what evidence
would confirm it, what evidence would refute it?"  Then you go look for
the confirming and refuting evidence.

One of the dismaying things about many Creationists is that they don't
seem to understand this -- that they have no comprehension of the amount
of testing of ideas that goes on.  One gets the feeling that their notion
of science is what's taught in text books.  So the thinking runs, you
evolutionists have your books, and we have our book, and it's the one
true book, so that takes care of that -- our book is better.

> As a good exercise (one rather beyond me, I should say; this really
> is the business of a good empirical scientist), one might consider
> how to test the several hypotheses about the origins of bipolar sex
> that Richard Harter just posted.  In that case, the "stories" are a
> lot closer to actual hypotheses that may suggest fruitful experiments
> to test them out --

Ah, but hypotheses were lifted straight out of the popular science journals
(Sci Am, Sci news, Discover and the like) with a sprinkling from books
by people like Margules (sp?).  Not being a professional biologist
handicapped by a sense of professional ethics, I am the enviable position
of taking speculations by the professionals as a launching pad for really
hairy chested speculation.  Actually, this sort of speculation really
can't be directly confirmed.  The best we can do is look for confirming
evidence, etc.  That said, let me speculate on the origins of biopolar
sex.

HYPOTHESIS:  Male gender is the end result of a viral infection.  Female
gender is a defense reaction.

DISCUSSION:  Consider a species (protist) that is originally monogametious.
Now consider a virus "wishing" to invade that species, freeloading on its
RNA and metabolism.  A particularly effective strategy is to invade the
reproductive system and attach itself to the chromosome controlling the
production of gametes.  Now it is part of the native original strategy of
the virus to produce as many copies of itself as possible, and this is
the strategy it will impose on its host, i.e. the host will produce many
more gametes relatively speaking than the norm of the species.  The
inevitable price, since the host has fixed resources, is that the gametes
thus produced will be relatively impoverished.  Now consider the rest of
the population which has not been invaded by this virus; it is faced by
a flood of scrawny gametes.  There are two major possible responses;
one is rejection, and the other is accomodation.  The accomodation strategy
is to accept the probability that ones gametes are going to get a scrawny
partner and endow ones gamete with extra resources.  One might ask why
the well endowed don't restrict themselves to other well endowed.  So
they might, except that the well-endowed who join with the infected can
now pass on the infection successfully.  In due course the viral genes
simply get incorporated into the genotype of the protist, and that,
children, is the story of how the boy protist met the girl protist and
love conquered all.
-- 
Richard Harter: SMDS Inc.  Net address: rh@smds.com Phone: 508-369-7398 
US Mail: SMDS Inc., PO Box 555, Concord MA 01742.    Fax: 508-369-8272
In the fields of Hell where the grass grows high
Are the graves of dreams allowed to die.
Newsgroups: talk.origins