Text 340, 193 rader
Skriven 2004-10-08 13:28:00 av Tim Tyler (1:278/230)
Ärende: Re: Interview with Mayr
===============================


Lennart Kiil <kiilx@xtele2adsl.dk> wrote or quoted:
> "Tim Tyler" <tim@tt1lock.org> wrote in message 
> > Lennart Kiil <kiilx@xtele2adsl.dk> wrote or quoted:
> >> "Tim Tyler" <tim@tt1lock.org> wrote in message
> >> > Michael Ragland <ragland37@webtv.net> wrote or quoted:
> >> >> Michael Ragland <ragland37@webtv.net> wrote or quoted:

> >> >> MAYR: There's absolutely no chance of the human species evolving. 

[...]

> >> >> Tim:
> >> >> Ernst Mayr doesn't have a clue about human evolution :-(
> >> >>
> >> >> MR:
> >> >> How so? I think Mayr was referring to Darwinian evolution.
> >> >
> >> > "There's absolutely no chance of the human species evolving."
> >> >
> >> > The statement is idiotic.  Does Mayr think all humans have
> >> > equal numbers of children?  Has he forgotten about the
> >> > existence of sexual selection?  What on earth is he thinking of?
> >>
> >> Not so fast. That fact that not all people have equal numbers of children
> >> does not necessarily warrant evolution, especially not in any directional
> >> sense. Such a claim relies on the premise that on average there is some 
> >> kind of correlation that connects the people having more children 
> >> with a certain genetic makeup.
> >>
> >> The same basically goes for sexual selection.
> >
> > That doesn't make the statement that we are not evolving any less
> > stupid.
> 
> I agree that Mayr far overstated the case when saying
> "There's absolutely no chance of the human species evolving."
> This statement borders on the absurd.
> 
> What I was objecting to was your inference from differential reproductive 
> output to evolution.
> Here is why, imagine we now live in an environment where number of offspring 
> relies more heavily on choice and not so much on natural capability. This 
> would reduce the correlation between reproductive succes and genetic 
> evolution because there might not necessarily be any segmented genetic 
> composition to the people choosing to have more children.

My questions to Mayr were rather rhetorical - and aimed at suggesting
what factors Mayr might have missed.

Even without differential reproductive success, you can't avoid
evolution in practice - due to genetic drift.

In fact, differential reproductive success will always decrease the 
effective population size - and will thus increase the magnitude of
the effect of genetic drift on gene frequency changes.

In an environment like ours - where individuals choose other individuals 
on the basis of their attractivness, resistance to diseases and worth as 
potential mates - and the environment is full of selection pressures very 
different from the one the species evolved in - differential reproductive 
success is practically bound to result in gene frequency changes.

> For example I live in Denmark where we have the socalled wellfare state. 
> This basically means that the burden of having children has been distributed 
> over society at large. This means that anyone, regardless of their natural 
> potentials can have a lot of children. [...]

Welfare suddenly makes the whole society more abundant?  I would expect
the average number of children in each generation to be roughly unchanged.

> This renders the whole idea of selection obsolete.

No - you must be kidding.  Welfare only redistributes material resources.  
It doesn't dictate who gets to mate with whom.  Females will still
get competed for.  What will actually happen is the practically the
reverse - welfare creates a different environment - a whole bunch
of strategies that used to work no longer pay off - and an whole
bunch of new strategies are needed.

Welfare exists in my country as well - but it makes no serious attempt
to offer everyong equal resources - it's main function seems to be to
prevent screwed-up individuals dropping off life's ladder too prematurely 
in a manner that wastes the resources the government invested in their 
education.

> Natural selection because natural potentialities are 
> leveled out by governmental redistribution.

So: in Denmark, all women are equally beautiful - and all men are
equally rich?  I would suggest that in fact the ground is not
/actually/ that level over there.

> Sexual selection because the obligation to help women support children 
> has been tranfered from the individual man to the state. In short 
> contingency and randomness is becoming relative more important than 
> more deterministic forces now than earlier in history. Thus I do not 
> agree that evolution (in a directional sense) occurs faster in humans 
> now than earlier, quite the opposite.

I would suffix that whole sentence with "in Denmark" - or you have a 
ridiculous syllogism on your hands.

> > There's a reasonable book-length treatment putting the case for humans
> > evolving in modern times faster - if anything - than before - due
> > to being in an environment which is different from the one they
> > evolved in - and because the difference in reproductive success
> > between the most successful reproductives and the least in modern
> > times is likely greater than at any point in history - i.e.
> > the Guinness record holders for offspring lived rather recently.
> >
> > The book is: "Children of Promethius" - by Christopher Wills.
> 
> As noted above, it does not sufice that the environment is merely different 
> to indicate more evolution, the environment has to be conducive of 
> directional evolution for this argument to hold. That is, it has to be an 
> environment that makes genes visible to selection. Modern society more than 
> anything obscures the genetic component.

Cultural evolution is the main motor driving genetic evoultion these
days.  The breakneck speed of cultural evolution radically transforms
the environment in mere decades.  Genes and culture co-evolve - and
so genes are dragged along for the ride.  The ride genes are on
is definitely accelerating - with sexual selection and genetic
engineering looking as though they will become dominant forces
in the arena of nucleic-acid-based genetic change.

> >> > As for speciation, it seems *highly* likely that strains of
> >> > asexual human clones will arise in the near future. [...]
> >>
> >> what is your concept of 'near future'?
> >
> > The first human clones?
> >
> > Cloneaid says they have 13 cloned human babies so far
> > [on http://www.clonaid.com/news.php].
> >
> > I don't know if that is true - but at least that number of
> > human clones will probably exist by this time next year.
> 
> Ahh ok, by asexual clones I thought you meant clones that could actually 
> reproduce asexually like parthenogenetic strains in some animals, this is an 
> entirely different matter.

Many of the early clones will be clones of infertile individuals for
which cloning is the only possible chance of reproduction.

If these individuals don't clone themselves they can't have babies - and 
many of them find that frustrating.  Obviously if they /do/ clone 
themselves their descendants are highly likely to inherit their 
infertility - and are likely to find themselves in exactly the same 
position - clone or die.

So - many of the very first human clones will effectively be 
parthenogenetic strains - who can only reproduce by cloning themselves.

> And it is going to be a while before clones start to matter in the global 
> household, compare:
> 13 : 6,400,000,000

How long will it be until clones matter?  Obviously a generation or so
at least.

I forsee at least two avenues for clones establishing themselves.

One is the cloned celebrity.  Celebrities are naturally in demand -
it only makes sense for there to be more of them to go around.
Celebrities will be cloned by the celebrities themselves, to reduce
some of the risks associated with them dying - and losing the franchise
associated with their identity.  Celebrities are also likely to be cloned 
with or without their permission - by individuals who love them and want 
to form closer associatons with them.

The other is cloned individuals to play specialised roles.  At least
some cultures will have no qualms about producing humans with genetic
specialisiations to fill particular roles in society.  Some of the
individuals will most likely be sterile clones.  Cloning will be basically 
done for the same reason that Ford cars are mass-produced in identifiable 
models - the behaviour of the results is known through testing, you don't 
have to offer technical support for multiple models, employers can read 
reviews of the model by other customers and know what they are getting, 
and R&D costs are minimised.
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