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Human evolution

Discussion of everything related to the Theory of Evolution.

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Human evolution

Postby James » Wed Feb 23, 2005 11:21 pm

Could it be possible that humans may have stopped evolving? As with most other organisms, 'survival of the fittest' leads to evolution, however in modern human times. We appear to be bypassing any factors that could cause evolution. For example, we now do not hunt, for we can just visit shops. There are no longer any physical factors to prevent any of us from passing our genes on, which leads to a diverse gene pool that is not heading for any particular direction in general. One could say that those seen as 'better looking' have this; however, there are not many people who could not find anyone to produce offspring with. Evolution through mutation seems unlikely as there would still be equal chance of surviving no matter how beneficial the mutation, as there a so little threats to humans nowadays. Extensive medical care further reduces the chances of humans evolving. Could it be possible that we have created a world that poses so little problems of anyone passing their genes on, that our evolution has halted? If not, how and why could we be evolving?
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Re: Human evolution

Postby mith » Thu Feb 24, 2005 12:16 am

James wrote: One could say that those seen as 'better looking' have this; however, there are not many people who could not find anyone to produce offspring with


Roflmao, that just made my day. Yes, it's easy to have children since you can get the state to take care of them if you're poor. Also there is a trend toward smaller family sizes so being rich and successful may not mean better chances of your genes surviving. In contrast the "masses" seem to be reproducing more(Jerry Springer et. al).
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Postby thank.darwin » Thu Feb 24, 2005 12:58 am

I have often wondered that myself... and if you think about it we have sheltered ourselves from natural selection (but not completely). If a disease comes along we try to come up with a cure for it - so it would seem as our medicine is evolving but not us. The problem is when a lethal virus comes along we will be wiped out...?
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Postby biostudent84 » Thu Feb 24, 2005 3:25 am

Human evolution, like all evolution is a slow, but ever continuous process. Proof that evolution has not stopped in humans is simply described by average height. Within the past 200 years, the average male height has gone fro 5'4'' to 5'10''. Also, today, some humans are being born without wisdom teeth. Since we usually remove them surgically, and do not use them if we don't, it is logical for us to evolve to not grow them. Growing an unused part of the body is a waste of energy.

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Postby mith » Thu Feb 24, 2005 5:30 am

Don't forget the most important human trait is cultural evolution.
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Postby thank.darwin » Thu Feb 24, 2005 1:16 pm

biostudent84 wrote: it is logical for us to evolve to not grow them.


Be careful there Kyle... we can't logically evolve. We have useless parts of the body that stick around because they don't affect how well we reproduce or how we gather food and so on...
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Postby biostudent84 » Thu Feb 24, 2005 2:09 pm

thank.darwin wrote:Be careful there Kyle... we can't logically evolve. We have useless parts of the body that stick around because they don't affect how well we reproduce or how we gather food and so on...


I am being careful. But as long as we all understand that evolution is not controlled, we can say these thigns. It still stands...if it is a waste of energy to grow a body part, we will evolve to get rid of it.

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Postby James » Thu Feb 24, 2005 3:42 pm

Evolution is the idea that a group in a species has something that enables them to more successfully mate and pass their genes on compared to the others in their species. Despite being useless, wisdom teeth and such useless organs such as the appendix would give neither an advantage nor a disadvantage in having offspring.
Why are we getting taller? Does this mean that those who are taller have a better chance of having children? Could it be the case that it is the very short people, nowadays are rarely having children? It could be that our human society is not only stopping evolution in some directions, but also aiding it in others, i.e. very short people are now seen as ‘abnormal’, and therefore have fewer children. Is this an example of cultural evolution?
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Postby biostudent84 » Thu Feb 24, 2005 5:36 pm

Becoming taller is part of becoming bigger. Over time all species when left alone will grow larger. It is called the "Red Queen" hypothesis. It comes from a poem in Alice's Adventures in Wonderland where the Red Queen was forced to run as fast as she could just to remain in place.
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Postby Fayt » Thu Feb 24, 2005 7:40 pm

I think we are evolving we just don't know it such as people in colder places like the Alps or Tibet are becomings hairer while people in warmer places are becoming less hairy. Something like that more or less.
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Postby RobJim » Sat Feb 26, 2005 9:30 am

Evolution occurs when any of these five factors happen:

*Mutation
*Gene Flow
*Genetic Drift
*Nonrandom Mating
*Natural Selection

Humans are exposed to mutagens, so we mutate. Humans do often travel to other parts of the world and breed with people from these other places, so gene flow takes place. Genetic drift doesn't generally take place, except for small populations like the Amish where they don't breed outside the population. People definitely do not choose who they mate with randomly. Lastly, natural selection does take place; people with genetic diseases may die or be unable to find a mate, people resistant to infectious diseases are more likely to reproduce, people from certain cultural groups and places may be more likely to die in war (such as Israelis, Arabs, Africans, etc)...

When these five rules fail to occur, the population is in a state called Hardy Weinberg equilibrium. This means no evolution takes place. Humans are not in HW equilibrium for the reasons I mentioned above, so we're evolving.

If you're interested, this website talks about it:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hardy_Weinberg.html

The top part is a mathematical proof; go ahead and ignore that unless you're into that kind of thing. Read from about two screens down onward; from where it says

So long as certain conditions are met (to be discussed next), gene frequencies and genotype ratios in a randomly-breeding population remain constant from generation to generation.

General biology texts should talk about it too.
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Postby biostudent84 » Sat Feb 26, 2005 5:33 pm

Might want to note that Hardy-Weinberg is theoretical. No species in nature is ever in equilibrium this way ;)
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