On Sat, 24 Jan 2004 06:51:05 +0000 (UTC), 
William Morse  wrote:

[snip]

> But more seriously. Symmetrical faces are found more beautiful (and I 
> can't cite references, but I have seen this numerous times, so I assume 
> it is true). If symmetry is an indication of health and lack of genetic 
> abnormalities (as Miller states and I can only hope it is on good 
> authority), then there can be selection for "beauty" without
any genes 
> having a direct effect on facial appearance (although there would have to 
> be alleles for genes that modify the response to that appearance).

In other words, you are not postulating a sexual selection mechanism
based on genes for beauty. You (Miller) are suggesting that a pretty
face indicates good health and men are more likely to mate with
healthy women. That sound reasonable to me. It suggests that there
shouldn't be any genes for a beautiful face because such genes would
interefere with the health detection phenomenon. I assume that the
same thing would apply to men. Ugly men are less healthy.

Thus, there is no good reason to suspect (according to this theory)
that there will be selection over time for women who are more
beautiful because they have superior genes.

> And no there is no assumption that facial beauty correlates with 
> reproductive success in the short term, rather that it correlates 
> with long term fitness. Let me try to explain (but note that I am 
> only parroting Miller - you might be better served by arguing with 
> him). Since humans in most societies are monogamous or polygynous 
> rather than polyandrous, and since the sex ratio is approximately 
> 50:50, and since almost all males seek mates, and since until recently 
> almost all couples (or multiples) had children, it is  impossible 
> for ugly women to die childless unless they die before reaching 
> child-bearing age. 

So far, so good. I assume we agree that there are VERY ugly men and
women who won't have kids. We probably agree that this sort of ugliness
is not heritable so it has no effect on the argument.

> And since children (again until recently) inherit one half of their 
> genes from their mother, we can guarantee that there will be very 
> little difference between the facial beauty of successful vs. 
> non-successful mothers _in the first generation_. But now we get to 
> long term fitness. Since almost all humans will mate, any difference 
> in preference will be reflected in assortation. Healthy females will 
> get to mate with the fittest males. while the ugly ones have to settle 
> for the rejects. 

Hmmm ... I suppose there might be an element of truth here but I'm not
sure I would accept this at face value. In any case, for your argument
to hold water there has to be a strong correlation between the appearance
of good health and some undelying genetics. 

> So their kids will (on average) be a little slower, a little more 
> prone to disease, etc. In other words their long term fitness will 
> be impaired.

How is this any difference than simple selection for fitness in the 
absence of sexual selection for beauty?

> And finally, if beauty is based on symmetry and related to health, 
> people will not (in fact _can_ not) become more beautiful _as individuals_ 
> through time (the overall beauty of the population can still fluctuate). 
> What they will do is keep pace with parasites. If people paid no 
> attention to health in their mating, it seems to me they would be 
> susceptible to parasites.

How did parasites get into this discussion?

> So we are left with two questions. One is whether there is any data 
> that links facial beauty with health. Miller believes there is. A 
> major reference he cites is Etcoff(1999) "Survival of the Prettiest". 

Seems reasonable to me that healthy people look prettier.

> I haven't read it. The second is whether there are genes that modify 
> the response to facial appearance. 

I doubt very much whether there are such genes with alleles that are 
segregating within the population.




Larry Moran
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