Leef_me nous apporta ses lumieres en ce 2008/01/09 13:58:
> Alain <ele### [at] netscapenet> wrote:
>> Warp nous apporta ses lumieres en ce 2008/01/02 15:53:
>>> Darren New <dne### [at] sanrrcom> wrote:
>>>> It's funny how many people won't deny something unintuitive like quantum
>>>> mechanics or relativity, stuff that's really hard to understand properly
>>>> even *with* math, but they're happy to deny the possibility of
>>>> evolution, which is easy to explain without any mathematics.
>>>   That may be because we can check the theory of relativity here and
>>> now, but we can't go back in time a few million years to check evolution
>>> nor we can perform evolutionary experiments which require a few millions
>>> of years.
>>>
>> There have been some evolutionary experiments that have been done. Some using
>> mice, others using insects. Take a mice colony and have it live in a lightless
>> environment, another in a chilly one, a third in a very hot one, a fourth in a
>> place where possible living area are far from food sources. Another one
>> prevented females from copulating for an increasing time.
>> Do the experiment over a few decades (some are still going on after over a
century).
>> In the dark environment you get mice with atrophied eyes, longer wiskers and
>> larger ears, and a high albinism incidence.
>> In the cold, you get longer hairs, increased body fat, short tails and smaller
ears.
>> In the heat, shorter hairs, slightly longer and spindly paws.
>> The ones that had to travel a lot devoloped longer, stronger legs, larger
>> stomach. They also devoloped hamster like cheeks.
>> In the last case, the longevity increased very significantly! Increases in the
>> order of +200 to 300% to the life span! We are now doing that experiment in a
>> very large scale: The whole Human Western and Asian populations! Asia, Europe,
>> the Americas, parts of Africa and Oceanya. From the middle ages to now,
>> generation time went from about 15 to 16 years to over 30~33 years...
>>
>> Those are called "forced evolution experiments". The key is to use speciment
>> that have a short generation time.
>>
>> --
>> Alain
>> -------------------------------------------------
>> There will always be beer cans rolling on the floor of your car when the boss
>> asks for a ride home from the office.
> 
> And yet, the animal that results is still a rat. Within its genes are the needed
> variability. All the conditions you described seem to me to be based on hormone
> production, not gene mutation or evolution.
Still mice or rats, yes. A new sub-race of the generic mice or rat, YES!
The observed changes do remain, unchanged, for many generations after the 
populations have been put back into "normal" environnements. There are cases 
where specimens from different environnements have become mutualy incompatible: 
they can no longer cross bread!
> 
> The human population increase in life span isn't based on evolution, but on
Not yet!
> better nutrition and heathcare. But maybe our brains "evolved" enough to
> realize we needed better nutrition.
Beter alimentation and health increase the longevity. Improve them and longevity 
increase immediately. Remove it and longevity immediately go down. There is no 
hereditary effect.

Late reproduction slow down the aging process. It becomes hereditary. It takes 
10's of generations to have an effect. For humans, it will take some more 
centuries. Remove that and the slowdown remains for 100's of generations. A few 
millenias for humans.
> 
> Leef_me
> 
> 
Evolution need many generations, usualy 100's to 1000's, in an environnement 
forcing some adaptive evolution. Recent studies show that the dodo evolved from 
the common pigeon, but no dodo could cross bread with a pigeon. Humans, chimps, 
gorillas and orangoutans only differ geneticaly by one FRAGMENT of one 
chromozome (two in the case of the gorilla: two fragments switched between two 
cromozomes).

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you hope that you can render your 
ideas on your PC before you die.
Sven Rudolph (Germany)

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