Michael Ragland  wrote:

> Ron:
> 
> You seem to make a contradictory statement. In one post you state, "I
> agree that we can't use evolutionary inferences to make our judgements,
> but we will be able to make certain determination based on quality of
> life and cost to society and decide that certain alleles would be better
> to have at a lower frequency in our population." In another post you
> write, "The only evolutionary justification for doing this is that we
> can predict what will happen if we let natural selection run its course
> in the current medical environment, and we decide that we do not want to
> follow that path." Do you draw a distinction between evolutionary
> inferences in making judgements and evolutionary justification in making
> judgements? 
> 
> There almost seems to be a slightly radical approach in your posts
> pertaining to artificial selection whereas John Wilkins displays
> cautiousness. Mr. Wilkins makes some statements which I find highly
> dubious.
> 
> He states, "Now suppose that some non-medical selective pressure arises,
> and that due to the increase in frequencies of previously deleterious
> alleles which happen to confer some relative benefit on bearers, the
> fitness of the overall population is increased by medical intervention
> in ways we could not foresee. Is medical intervention *still* lowering
> the "genetic health" of our population?" Can Mr.
Wilkins provide one
> example of this? 

This is a thought experiment. Not only am I not a biologist, but I am
mathematically illiterate, so I won't pretend to do the population
genetic calculations. But suppose the case I discuss did occur - on what
grounds would we be able to say that the "health" of the gene pool for
that deme was lowered?

I can think of the following:

1. We have some prior "engineering" standard, as it were, for optimal or
best-result functioning. This immediately raises the spectre of
teleology - why is that standard the one that counts? In evolution,
there are no preset goals.

2. We have some standard of "natural" or the "default"
state of the
gene-pool. But this, of course, is based on the outcome of *prior*
evolution and environments. Evolution is, in part, adaptation to *new*
environments.

3. We have present standards of actual lifecycle outcomes. But as I
said, if the alleles are increasing, then how does it matter if humans
or any other organism survives much beyond reproduction or has a happy
life?

Relative advantages in biology are *purely* defined after the event in
terms of the reproductive rates of alleles. Anything else is either
moral or social or both in its origination and character. All I was
trying to say is, if medicine does something that results in an allele
being fitter in a medical environment, and a medical environment
persists long enough to make a difference to allele frequencies, then
medicine is not, on a biological definition, affecting fitness
negatively, except for those alleles that are now relatively less fit.
> 
> Mr. Wilkins also writes, "The point is that such concepts as
"health"
> and "fitness" are contextual anyway, and relative. And we
cannot foresee
> what will be fitter than another allele when both can - in the present
> environment - reach maturity and reproduce, even if it does involve
> treatments like insulin, etc. 
> 
> As you state, however, ""In the current medical environment certain
> alleles are increasing in frequency due to relaxed selection. This just
> causes the genetic load to increase for the human population. We can
> survive this increase as long as our medical technology can deal with
> it. The cost to society will increase with each generation, but the
> frequency of detrimental alleles will increase until we hit the
> selection threshold and we start observing selection against those
> alleles. I don't know if I'd want to be a member of such a population at
> that time in their history. Artificial selection against certain alleles
> may be warrented to slow or arrest the increasing genetic load. The only
> evolutionary justification for doing this is that we can predict what
> will happen if we let natural selection run its course in the current
> medical environment, and we decide that we do not want to follow that
> path. To give an extreme and ridiculous example, if medical technology
> became perfect and we could fix just about everything, the only things
> that you might consider to be neccessary to be human would be your brain
> and your gonads, and you could have those mobile in a bucket on some
> robotic platform. Think about blind cave fish. Medical technology can
> allow a lot of genetic defects to survive and reproduce. Since we have
> altered the threshold of natural selection, to keep the status quo you
> will have to institute artificial selection or accept the consequences
> of the new selection criteria."
> 
> I think you are right. We have altered the threshold of natural
> selection. It no longer works as effectively as it once did and this is
> in large part due to developments in science and medicine. A glaring
> testimonial to the fact natural selection no longer works as effectively
> is human overpopulation. 

To say that "selection is relaxed" for an allele is not to say that
selection for *all* alleles is relaxed. Medical technology changes the
selection coefficients, but in no environment is there no selection for
anything, unless the growth rates are hyperbolic (i.e., open ended
without carrying capacity restrictions). Even in the most
medical-technology competent social environment, there will remain some
selection coefficients against some alleles. It is inevitable, so long
as there are limited resources.
> 
> We can't afford to continue to rely of a weakened natural selection or,
> as you point out, the genetic load and overpopulation will eventually
> force a new selection criteria. On the other hand, I think one has to be
> extremely careful when it comes to supporting instituting artificial
> selection because it may evolve into a "radical new selection
criteria".

The main difference between artificial and natural selection is that one
is based on selection coefficients imposed by humans. We know from
classical economics, game theory and discussions on social coordination
and convention that these are not imposed directly through rational
thought and planning, and that in such cases where they nearly are, the
criteria may as well be arbitrary anyway.

And we are already subject to new selection criteria in some pathes of
our total species range - e.g., in dense urban environments in the
subcontinent, for example, or in similar situations in developed
coutnries. The selection pressures are different - for a start there are
different pollutants in each environment. I suspect that many autoimmune
diseases are due in part to environmental stresses.

.....

> 
> John Wilkins states, "You are still begging the (evolutionary) question
> here - what gives you the right to call them "defects"? All
they are is
> alleles. If they increase in frequency, then per definitio they are
> fitter than alternative alleles that do not. The fact that they are not
> fitter in some other ("natural") envirnment means nothing unless that
> environment is imposed. All evolutionary fitness is relative to the
> *actual* selection regime."
> 
> That's a pretty lame rationale for genetic health. It's a fact because
> of modern medicine and science natural selection no longer works as
> effectively. As a consequence many of those born today with various
> ailments would have been naturally selected against in the past. But
> irrespective of this if somebody is born with cerebral palsy, Down's
> syndrome, and hundreds of other diseases or disorders....they are
> diseases and disorders whether they've been naturally selected against
> or not. They are genes but they are not "just alleles".   

So far as I know cerebral palsy is a developmental accident, not a
genetic disease. Very few of the things usually called "diseases" of
this kind seem to have any actual genetic basis, apart from the
metabolic disorders like phenyketonuria, Tay-Sachs, sickle cell anemia,
and so forth.

But the argument is not whether we can say that there is an effect on
the overall health of a population due to medicine (we should hope that
there is at least a positive one, and the increased rate of infant
survival in all countries is an instance), but whther we can give a
sufficient account on *evolutionary* terms that enables us to make this
judgement call. There is not. Evolution is, in the end, evolution. We
must be very clear that these decisions are taken on *social* grounds,
not biological ones. If it turned out that a world of total morons, with
a lifespan of twenty years in pain and misery, had a higher fitness for
hominids than a world where humans live to 120 in good health and with
intelligences that rival Einstein's, then so far as evolution is
concerned, the former case will beat the latter. End of story.

Now I do *not* want to live in that world (and I suspect that I live in
it more than I live in the other scenario), so I would promote medical
intervention to eliminate such alleles, where they can be identified.
But I would also say that we need to realise this is not a decision
based on genetics or evolution. And I would say that we need to take
account of moral rights when we do it, and as a good Rawlsian (a
political philosopher) I think that we should set up our understanding
of rights as if we know nothing of our own and our children's and
grandchildren's position in society. And this is true enough as well, in
most cases, at least for the grandkids.
> 
> All evolutionary fitness is not relative to the "actual selection"
> regime. I can appreciate the non-absoluteness of the current selection
> regime but does one support parents voluntarily deciding to terminate a
> pregnancy which has positive results? Mr. Wilkins indicated he supports
> amniocentesis in clear cut cases of a genetic disease and disorder. What
> if the parents were told there was a 50% chance of the child developing
> a disease early in life?
> 
> Also, as has been pointed out in the future parents will be able to
> select for traits such as eye color, hair, etc. Sex can already been
> selected for. Should there be a selection criteria established which
> states parents can't terminate a pregancy on the basis of sex, that
> parents can't select for traits such as hair and eye color, etc. Don't
> you think some kind of selection criteria will be needed?

Sure. But not based on the "lessons that genetics teaches us" or any
such twaddle.

And you can call me John, or Wilkins. Mr Wilkins was my dad.
> 
> Michael Ragland


-- 
John Wilkins
"Listen to your heart, not the voices in your head" - Marge Simpson
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