Orchid Win7 v1 <voi### [at] devnull> wrote:
> I love the suggestion some people are making that maybe humans will 
> "evolve" to be less fat.

> This makes it sound as if "evolution" is some magical process whereby 
> each time we reproduce, our DNA gets optimised to our situation, so that 
> as generations pass, everybody slowly improves...

Indeed, genes do not "try" to do anything. They just change slightly with
each individual that's born. Whether those changes will be retained and
widespread throughout the population (during the next few thousands of
generations) depends on lots of things, but mostly on whether it helps the
individuals with that particular change to have a slight edge over those
who don't. (Although sometimes a change can be retained even if it's not
particularly beneficial, as long as it doesn't decrease survival rates.)

Another thing that many people don't understand is that a change in a
gene can have several consequences. The one and same mutation can cause
several effects, some of them can be beneficial and others neutral or
even detrimental. However, it sometimes happens that the benefit is greater
than the harm, in which case the change may get preserved and spread to
future generations. This is often the source of genetic mutations that
seem detrimental and hinder survival rates. On their own they may seem
contrary to natural selection, but more often than not, it's simply a case
of the same mutation causing both beneficial and detrimental changes at
the same time.

I have been thinking that humans have evolved to a point where rather
than becoming better, we may in fact be becoming worse. Because of
progress in healthcare, nutrition, and all other kinds of things that
help people survive, all kinds of detrimental changes to our genes are
not being removed from the gene pool, which means that over time our
genes will become more and more trash. I'm expecting that as further
thousands and thousands of generations pass, the number of genetic
disorders and diseases will only increase in prevalence, simply because
there's nothing removing them from the gene pool.

Basically the only hope we have is if medical science advances to the
point that we can fix those genetic disorders, and our moral philosophy
advances to the point where we allow ourselves to do so.

> No, this is not how evolution works. When you say "humans will evolve to 
> be less fat", what you're actually saying is "all the fat people will 
> die". Because THAT has how evolution changes stuff.

Actually, for humans to evolve to be less fat would require

1) for obesity to be an inherited trait (that can change without causing
   ancillary side-effects that are worse), and
2) for people with this trait to never reach a reproductive age.

Not very likely to happen.

-- 
                                                          - Warp

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