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Author Topic: Human Evolution has hit a Dead End  (Read 7427 times)

Offline pirunner

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Human Evolution has hit a Dead End
« on: 28/02/2008 00:59:26 »
I may be way out of the loop on this, but what is the status quo on this theory:

Human evolution has increasingly slowed over the past centuries due to a continual improvement of science and technology; with an increased knowledge in these areas, humans can easily "fix" or "accommodate" the traits that would otherwise have been weeded out by natural selection. Furthermore, human evolution is or will soon completely cease to exist; without the "selection" part of natural selection, humans cannot continue to evolve.


 

another_someone

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Human Evolution has hit a Dead End
« Reply #1 on: 28/02/2008 02:03:21 »
What evidence do you have for the speed of human evolution - and how would you measure it?

There are animals that have evolved not a lot over tens of millions of years, and humans have only been on this planet for just over 100,000 (at least as far as homo sapien sapien, although someone longer if one includes our ancestral species).  Then again, there are are species that have only existed for centuries, or even less.

Yes, certainly technology has reduced some of the environmental pressures on humans (although it has added others) - but that too is part of evolution (a bee hive is technology for a bee, but does that mean bees are an evolutionary dead end?).
 

Offline pirunner

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Human Evolution has hit a Dead End
« Reply #2 on: 28/02/2008 12:33:15 »
Evolution does not work unless there is competition between organisms. What kind of competition is there today that is weeding out the "least fit" humans?(There's no great way of saying this when dealing with humans- but least fit is how it's described with other organisms)
 

another_someone

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Human Evolution has hit a Dead End
« Reply #3 on: 28/02/2008 12:52:43 »
Evolution does not work unless there is competition between organisms. What kind of competition is there today that is weeding out the "least fit" humans?(There's no great way of saying this when dealing with humans- but least fit is how it's described with other organisms)

Competition is not simply about animals, it is about genes.

Ofcourse we have competition, at several levels.  There are many parasites that do effect us, and that we need to continually adapt to cope with (there is much speculation that one of the consequences of the HIV epidemic will be a change to the human genome - but this depends on us not finding a cure to HIV).  There have even been some who have speculated that the exposure to bubonic plague epidemics that Europeans have had in the past may already have given them some greater immunity to HIV than is true of some other populations.   But the real competition we face is with each other (some humans will thrive better than others - and not always in obvious ways).  In that respect, society and technology do not mitigate that competition, but merely provide a context in which that competition occurs.

Ofcourse, there is always an argument, in any environment, once you have got to the top, where else is there ultimately to go but down.  If that is the case, or will some time in the future be the case with humans, then what is your solution?
 

Offline angst

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Human Evolution has hit a Dead End
« Reply #4 on: 28/02/2008 14:53:19 »
If that is the case, or will some time in the future be the case with humans, then what is your solution?

Ahhh... the unpalatable question...., the corollary of the argument is all too clear.
 

Offline jaycee

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Human Evolution has hit a Dead End
« Reply #5 on: 28/02/2008 23:24:41 »
This is entirely my opinion and as such has no scientific basis, but I suspect that there is a two tier system of evolution.
Slow evolution that occurs over many generations and is a responce to a need within a species to take advantage of something specific.
Fast evolution which is a responce by the female of a species to social or environmental pressure that allows for rapid change to cope with impending disaster or disaster that has occurred.
I further suspect that the female of a species has the ability to subconsciously rewrite DNA and program a foetus with new information that will increase its chances of survival.
It may not be that every female can do this. but I suspect a percentage can.
Slow evolution is a survival trait that allows for gradual social/environmental change.
Fast evolution is a survival trait that allows for rapid social/environmental change.
I believe that rapid change is primarily triggered by global events that wipe out large swathes of population.
It may well be that higher order creatures such as man are more able to adapt than lower order creatures.
Without research who really knows?
« Last Edit: 28/02/2008 23:36:20 by jaycee »
 

Offline pirunner

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Human Evolution has hit a Dead End
« Reply #6 on: 29/02/2008 00:32:42 »
But the real competition we face is with each other (some humans will thrive better than others - and not always in obvious ways).  In that respect, society and technology do not mitigate that competition, but merely provide a context in which that competition occurs.

I completely agree with the fact that HIV and other powerful viruses/microorganisms do have potential to change the human gnome. In addition, to you stipulation that this would really on us NOT finding a cure, I would also like to add the condition that some humans would have to be either immune to the virus or at least less disposed to acquiring it. (Please tell me if this is true or possibly even if it has been found).

Also, can you please elaborate on the above quote. This is the aspect of the topic that I am not quite sure about. The only competition that I can readily observe is that of economic competition. This, however, is related to learned traits and does not posses the power to change our gnome. 
 

another_someone

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Human Evolution has hit a Dead End
« Reply #7 on: 29/02/2008 01:14:10 »
I completely agree with the fact that HIV and other powerful viruses/microorganisms do have potential to change the human gnome. In addition, to you stipulation that this would really on us NOT finding a cure, I would also like to add the condition that some humans would have to be either immune to the virus or at least less disposed to acquiring it. (Please tell me if this is true or possibly even if it has been found).

Yes, I do not know the percentage (it is low, maybe 1%) of humans do seem to be immune to HIV (I think it is something to do with different types of immune response, and some people with a more primitive immune response can avoid having HIV compromise that immune response).

There has also been some debate, but I don't know how credible, that different populations may have different susceptibility (hence my comment about speculation regarding European exposure to bubonic plague or smallpox having primed out immunity to HIV - but I thing this is not widely accepted - more likely the better nutrition and lower general infection rates in Europe provide us with a better chance of fighting it off).

But it is not just about HIV being a selection force upon the human genome, but the nature of retroviruses is that they work by directly inserting themselves into the hosts DNA, and then sometimes they become stuck there, and so be part of the genome of that individual.  If the insert themselves into the DNA of a gamete, then they can be passed on to the next generation.  All species are believed to have remnants of ancient retroviruses carried in their DNA - although the remnants are believed to be inactive, but it was one of the concerns regarding xenotransplantation, that such a remnant could become activated after transplantation.


Also, can you please elaborate on the above quote. This is the aspect of the topic that I am not quite sure about. The only competition that I can readily observe is that of economic competition. This, however, is related to learned traits and does not posses the power to change our gnome. 

Yes it does - in crude terms, rich guys get to bed more girls.

OK, that is simplistic, and it is not all about wealth (although it certainly is a major factor), but there is no question that some men will father more children than other men, and so will influence the future human genome.  There are also differences in female birth rates (which is probably a greater factor in humans than in most other species, although there are some other species for which it is also true).

Aside from birth rates, there are also death rates.  Compare the relative growth of populations in the last 500 years between people of European origin and people of Native North American origin, and ask yourself has the human genome in North America changed in the last 500 years (it is still changing, although the changes may now be in a different direction).

Ofcourse, again, the above is simplistic; because the changes are far more complex than a mere displacement of one population with another, since it includes a significant amount of genetic mixing that came with it - but that only even more complicates the changes in the genome, but in no way reduces the amount of that change.
« Last Edit: 29/02/2008 01:24:54 by another_someone »
 

Offline that mad man

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Human Evolution has hit a Dead End
« Reply #8 on: 29/02/2008 17:31:01 »
I cant see how Human evolution can cease to exist unless we do.

At this time in our current history differing ethnic societies that were once very separate are now interacting and breeding leading to a greater ethnic mix. DNA in those circumstances I think will carry on evolving for many years to come.

 

Offline RobotGymnast

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Human Evolution has hit a Dead End
« Reply #9 on: 29/02/2008 22:51:38 »
I agree with this.. I myself suggested this to many people, but nobody seems to listen too much. Evolution is based on 'Survival of the fittest'.

It's not quite that evolution STOPS with this, because the benign mutations still survive and continue getting passed on, it's just that bad mutations survive and may get passed on as well, so now evolutions going a bad way as well as a good way.
 

another_someone

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Human Evolution has hit a Dead End
« Reply #10 on: 29/02/2008 23:13:58 »
I agree with this.. I myself suggested this to many people, but nobody seems to listen too much. Evolution is based on 'Survival of the fittest'.

It's not quite that evolution STOPS with this, because the benign mutations still survive and continue getting passed on, it's just that bad mutations survive and may get passed on as well, so now evolutions going a bad way as well as a good way.

This is a naive view of evolution.

In evolution, there is no good and bad, only what works and what doesn't work; and by definition, if it doesn't work, it does not survive.  But you also have to bear in mind that all of this is contextual - a mutation that helps drought resistance is useless in an environment that is has to deal with an excess of water; while a mutation that helps survival in a aquatic environment is useless in the middle of a desert.
 

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Human Evolution has hit a Dead End
« Reply #10 on: 29/02/2008 23:13:58 »

 

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