[ExI] IQ and beauty

[John Clark]

On Wed, Oct 7, 2015  Dan TheBookMan <danust2012 at gmail.com> wrote:

​> ​
> Well, an issue here is whether the particular trait or set of traits is
> determined by a gene or set of genes in the first place.
>

​That would be a more complicated example especially if the various genes
were a long distance from each other on the chromosome, but the end result
would be the same because females who had a gene or genes for liking long
tailed males probably had a mother who also had a gene or genes for liking
long tailed males and probably mated with such a bird. Therefore a bird
probably has a gene or genes for both producing a long tail AND a gene or
genes for liking a long tail. And that is the recipe for a disastrous
positive feedback loop.


> ​> ​
> Imagine this instead. The detection mechanism itself is wide-ranging. It's
> not a general beauty detector
>

​Beauty is not objective it is in the eye of the beholder. And a gene does
not live in isolation, a gene is not good or bad  ​in itself but only in
relation to its environment, the other genes in the genome. Some teams of
genes are good at getting into the next generation and some teams are not
even though an individual gene might be great if it were on another team.


> >
>> ​>​
>> A mutant bird with a smaller more aerodynamic tail would probably live
>> longer because
>> ​ ​
>> he would be better at getting food and avoiding predators, but fewer of
>> his genes would
>> ​ ​
>> get into the next generation because he would have trouble finding a mate.
>
>
> ​>​
> That's the typical tale :) with peafowl. Not sure how well it's been tested
>

Ronald Fisher
​, probably the greatest biologist since Darwin,
tested
​the idea ​
with the African long-tailed widowbird
​ back in the 1930s​
. The tails of ​widowbirds
​of​
 average length (but still too long for
​optimal​
 aerodynamics) were cut several inches shorter and released back into the
environment and their behavior followed for many years. Just as predicted
those widowbirds lived longer than average but had fewer descendants.
​It was also​
 found
​that when ​
widowbirds with unusually short tails
​had​
 artificial tails
​surgically attached
 to bring them up to average length they didn't live as long as
​their​
 fellow ​
short tailed birds without the prosthesis but
​they ​
had more descendants
​.​

​And​
 that too was as predicted.


> ​> ​
> What I've heard used as an explanation is having a outsized tail anving is
> kind of proof to the peahen that the peacock is fit overall because a less
> overall fit male with the same large tail would likely end up as dinner or
> otherwise in dire straits.
>

​Maybe, but for whatever reason the female is choosing to mate with birds
that have grossly un-aerodynamic tails, and that does not bode well for the
future of the species.

 John K Clark
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