On Sat, 31 Jan 2004 00:52:40 +0000 (UTC), 
William Morse  wrote:
> lamoran{at}bioinfo.med.utoronto.ca (Larry Moran) wrote in
> news:bv23as$25ct$1{at}darwin.ediacara.org: 

[snip]

>> 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.
> 
> Yes. I may have used the term sexual selection, and that is certainly 
> what Miller's book is primarily about, but in this case the hypothesis 
> is that faces are considered attractive based on features that indicate 
> health. 

Please note that this hypothesis is not connected to evolution. It may 
seem that way because many people assume that whenever you hypothesize
about some sort of selection it automatically follows that this
explains evolution. Not so. We need to think about the meaning of
evolution so that we can discuss this in a more scientific manner. I'll
take the standard textbook definition of evolution and assume that 
you agree with it. (I know there are some people who don't understand
the definition of evolution but you're not one of them.)

In order for beauty to be selected you have to have certain alleles
segregating within the population. There have to be alleles that
control beauty and alleles that control our reponse to this beauty.
Furthermore, the hypothesis has to do far more than just explain
why we think something is beautiful. It has to explain why this 
might have an effect on the ability to reproduce. So far, I haven't
seen any data to suggest that there's a serious difference in the
ability of beautiful men and women to reproduce. I also haven't
seen any serious attempt by the hypothesis to describe this. (In
fainess, it's probably assumed to be obvious that only people
with beautiful faces will get a mate. The fact that's there's no
data to support this assumption seems to be ignored ... as is the 
common sense observation that most men and women have children
eve if they aren't beautiful.)

> Note that, in addition, males prefer more feminine faces 
> (features reflecting relatively high estrogen values) while females 
> under some conditions  prefer more masculine faces (features 
> reflecting high testosterone levels). Explanations for this have 
> been proposed based on high hormone levels being an "honest
handicap", 
> but it has also been noted  that this may simply be a result of the 
> organization of the visual system to discriminate between male and 
> female faces. 

I prefer explanations based almost exclusively on cultural (societal)
patterns of behavior and what we learn when we are growing up. To
me, this explains the wide variety of different perceptions of
beauty in different cultures and the change in this perception
within a single culture over time. In other words, this behavior
doesn't have a direct genetic component and doesn't have anything much
to do with evolution, in my opinion.

I also like to compare human behavior with that of our closest 
evolutionary relatives in order to get a reality check on the latest 
evolutionary speculations about human behavior. In this case, I don't 
think that there's any evidence for chimps being particularly picky 
about their choice of mating partners. Thus, the speculators have to 
add one more thing to their hypothesis. Not only do they speculate 
about genes for beauty and genes for the perception of beauty but now 
they have to speculate that these genes mostly arose within the human
lineage in the past 5 million years. That's asking an awful lot for
a speculation that doesn't even have any evidence to support it.
(I'm talking about evidence for evolution.)

>> 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.
> 
> Yes, if women are considered "more beautiful" because they are more 
> symmetrical, (this also applies to more average - another supposed 
> indicator), there can be no long term selection for more beautiful 
> - as opposed to say selection for greater height. 

I'm glad we agree. 

>>> 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.
> 
> Just so I'm sure I understand you - this sort of ugliness _might_ be 
> caused by genes but represents a highly unlikely combination of rare 
> alleles and so is not _heritable_ outside of highly inbred populations.

Yes. There might be mutations that so disfigure a person that he/she will
have little chance of becoming a parent. These don't count. The vast
majority of things that might affect beauty are probably not genetic.
They include things that happen by chance during development and
birth and things like disease and accident that happen during childhood. 

>>> 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. 
> 
> Interesting - I had thought that assortative mating was the least 
> controversial part of my argument. And in fact there is research that 
> indicates that females who consider themselves less attractive show less 
> discrimination in male attractiveness than females who consider themselves 
> more attractive - an argument in favor of assortative mating.

If there is no strong genetic component to beauty and no strong *genetic*
connection between being beautiful and preferring beautiful partners,
then we're not talking about evolution.

The data you quote is, in fact, strong evidence against the speculation.
It looks like people can easily modify their perception of beauty (and
the desirability of mating) by simply looking in the mirror. If they
see a very beautliful face in the mirror then they want a very beautiful
partner. If they see a less beautiful face then they expand their 
target to include less beautiful people. Those studies are interesting 
but the real question isn't about desires and wishes. The real question
is about the end result. It would be nice to look at who the beautiful
and less-beautiful people actually marry and raise children with.

A lot of people seems to making the assumption that just because we
have an idealized image of (culturally derived) beauty it means that 
we will only marry the ideal woman or man. This isn't the kind of world 
that I see around me. How about you?

> But your argument is more with the question of whether beauty is more 
> than skin deep - haven't I heard that expression somewhere before :-) 
> And after doing some more checking on the subject, you may  have a 
> point. There are several studies that show no relationship between 
> attractiveness and either health during teenage years or long term 
> health. Interestingly, attractive faces were judged as more healthy 
> even though they were not. This point was discussed in a very good 
> review article of the subject -  http://psych.unn.ac.uk/pdf/face.pdf
> The authors adopt an adaptationist stance, which you may disagree with, 
> but they do a good job of discussing the pros and cons of the "good 
> genes" theory for facial attractiveness, and they give references for 
> both the pro and con arguments. They point out that an attractive face 
> might still be an honest indicator of health in the ancestral environment. 
> They did note one study comparing attractiveness with health in a more 
> primitive culture - that study actually found a positive correlation 
> between facial attractiveness and fertility, which both you and I 
> agreed would not be expected.

This is just one part of the speculation. The idea being challenged
above is that selection for beauty can be explained by a correlation
between beauty and health. I'm going further. I'm challenging the
entire idea that beauty is being selected in human populations for
whatever reason.

> (snip)
> 
>>> 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.
> 
> It also seemed reasonable to me, but as I noted above (see for 
> instance www.zoology.uwa.edu.au/staff/lsimmons/ElectronicPapers/
> Rhodes2003.pdf) it may be that pretty people look healthier!

That's a complication. I'm sure the adaptionist behaviorists will
come up with some way to explain it. They're very good at 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.
> 
> Well, but there is the condition of having difficulty recognizing 
> faces - prosopagnasia. This can be caused by trauma to the head, 
> but can also be genetic. In general it is only recognized in its 
> most severe forms, but there is a continuum in effects - so there 
> is some diversity in the population at the alleles that code for 
> overall face recognition. 

I'll assume that this is tongue-in-cheek and you just forgot the 
smiley.   :-)

> If difficulty in even recognizing faces shows some allelic diversity, 
> then one might suppose that there is considerable more diversity in 
> genes for recognizing facial attractiveness. Unfortunately my web 
> searches on the subject tend to either steer me to sites on 
> prosopagnosia or to general discussions of facial attractiveness.  

This doesn't surprise me. Real data seems to be in very short supply
in evolutionary psychology.



Larry Moran
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 2/1/04 2:59:36 PM