Human evolution

in article [email hidden], Lars at
[email hidden] wrote on 10/23/03 4:50 PM:

Quoted message said:

I assume natural selection of individuals of the human species has more or less come to a
standstill.

That would be a clearly false assumption.

Quoted message said:

Everyone can usually have as many descendants as s/he wishes to have,

Note that this does not diminish the potential for natural selection at the individual level, unless
it results in every individual having the same number of offspring, which it hasn't, or the loss of
heritable variation for fitness, which I would find astonishing. Do you know of any evidence of the
latter possibility?

Quoted message said:

the species mutates and mutates without any goal, not only the ones who would traditionally have
survived in a hostile natural environment can pass on their genes to future generations.

If genetic engineering was not used as a mean to control/improve the quality of heritage
information of the human species, how long would it take until the quality of the human DNA had
significantly degraded?

How would you measure the degree of DNA quality degradation? I would ask about the reproductive rate
of the individuals, which you started off saying was quite high. Unless you have a different measure
of DNA quality in mind, it seems to me that your scenario is self-contradictory.

Guy

"Lars" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Hi,

I assume natural selection of individuals of the human species has more or

Hej du (om du är svensk) Lars,

Being in a gloomy mood at the moment, it almost gladdened me to see that someone (you) casts this
kind of contemplation in this individual-centric way! :-|

Quoted message said:

less come to a standstill.

No, only seen from the perspective that you are looking at it.

It is still going on. E.g. there are pressures in the form of industrial poisons that put plenty
of consistent and longterm pressure on individuals and population. We are not yet capable of
curing much diseases and cleaning up much contamination yet. Also small pockets (niches - social
such, for want of a better word) exist wherein small-scale natural selection can be spotted but of
course 'senza' any surely visible or readable speciating results - because any currently taken snap-
shots (or I guess even as recently taken as within the last ~100k yeras or so?) of such a slow-
moving 'thing' as our own evolution don't help us to pick up any new clearly and definitely
phenotyping trend.

Individuals that are 'fertiliously neurotic' (usually combined with being in some way fanatic and/or
religious) or, better put, ditto *AEVASIVE* tend -- whether they are poor or rich -- to breed a lot
more prolifically than people who are "less so".

I don't see that this will ever change, unless some very unusal selection pressure (I can't think of
one!) that "suits" a decisively naturally selective preservation of a pocket of population/people
whose geno (or even just pheno) type makes them more profoundly self-aware and self-regulating
(hence less AEVASIVEly selectively unconscious) than what is normal within most current (and
historical and prehistorical) individuals, cultures, and societes.

Quoted message said:

Everyone can usually have as many descendants as
s/he wishes to have, the species mutates and mutates without any goal, not only the ones who would
traditionally have survived in a hostile natural environment can pass on their genes to future
generations.

No, not even now. There are a few new kinds of hostile environments around these days.

Quoted message said:

If genetic engineering was not used as a mean to control/improve the

quality

Quoted message said:

of heritage information of the human species, how long would it take until the quality of the
human DNA had significantly degraded?

"Quality" relative to which/who's norms?

P

Lars said:

Hi,

I assume natural selection of individuals of the human species has more or less come to a
standstill. Everyone can usually have as many descendants as
s/he wishes to have,

So, why are the women chasing after Brad Pitt, rather than me?

the species mutates and mutates without any goal, not

Quoted message said:

only the ones who would traditionally have survived in a hostile natural environment can pass on
their genes to future generations.

So, those selection pressures have been eased. But there is probably more selection pressure for
things like alcohol tolerance nowadays.

Basically, natural selection has not stopped, it's just that the selection pressures have changed.

Bob

--
Bob O'Hara

Rolf Nevanlinna Institute
P.O. Box 4 (Yliopistonkatu 5) FIN-00014 University of Helsinki Finland Telephone: +358-9-191 23743
Mobile: +358 50 599 0540 Fax: +358-9-191 22 779 WWW: rni.helsinki.fi~bohOpen ↗

"Lars" <[email hidden]> wrote in message

Quoted message said:

Everyone can usually have as many descendants as s/he wishes to have,

So under modern circumstances, there is selection for wishing to have many descendants.

Quoted message said:

how long would it take until the quality of the human DNA had significantly degraded?

It depends what you mean. Instead of evolving under the pressures of the African savannah, we are
now evolving under pressures like housing shortages, abortion laws, and contraceptive pills. DNA in
ten thousand years' time may be a lot better if you want to be a Roman Catholic management
consultant, a lot worse if you want to hunt elephants.

As for the timescale for degrading the ability to hunt elephants on the African savannah, the
answer is quite quickly in evolutionary time. How many people suffer from myopia, for example? In
terms of political policies, however, the timescale is several generations, which is too long for
any urgency.