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Current Human Evolution

  1. Jul 30, 2003 #1

    Another God

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    I've got myself into a debate about whether Evolution is currently occuring in Humans.

    So far, with my initial thoughts on the subject, no matter how I approach the topic, I can only formulate Affirmative arguments. Can anyone think of any sort of case that can be built against the stance that humans are currently evolving just like everything else?

    (Even if you need to 'select' your definitions, choose your versions of evolution, your types of selection or whatever...)
     
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  3. Jul 30, 2003 #2

    LURCH

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    That is a tuff one. The best I can come up with is that the human race has reached a point where we are able to alter our environment to suit ourselves, rather than altering ourselves to suit our environment. You could try saying that once we began builing homes, furniture, machines etc. to fit us perfectly the way we are, pressure to eveolve ceased because any alteration from our current configuration would be a dissadvantage.

    It makes sense if you don't look at it too closely.
     
  4. Jul 30, 2003 #3

    Phobos

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    Agree. When you do examine it closely, it falls apart. :wink:

    A.G. - I think one would need to seriously redefine/limit the terms of evolution in order to say it's no longer happening.
     
  5. Jul 30, 2003 #4

    iansmith

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    I think evolution is still taking place but the enviromental pressure has change, mostly, in developed country. We still face disease and microbial attack. For example, some people are showing resistance to AIDS. If this resistance has a genetic basis then AIDS resistance migth be a new starting point for evolution.

    Another theoritical example is that people are becoming excessevly obese. There migth be biological and social pressure for obsese people to be selected against. Therefore people with faster metabolism migth become the fitter individual. People with faster metabolism migth have a better overall health and migth be more fertile.

    With human, social pressure and technology have an equal voice with mother nature when it comes to evolution wheres with animals technology (a wood stick to get ants is technology for a chimp) and social pressure have less influence.

    Evolution also migth take a long time therefore we migth not see the results.

    [Edit: spelling]
     
  6. Jul 30, 2003 #5

    Another God

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    Thats exactly the problem. I keep trying to think up angles on which a negative side can argue this...but every superficially convincing argument is crap upon inspection. And for this debate so far we ahve only decided which topic we want to do, and the teams haven't been sorted yet, so I don't know whether I will get to be on the affirmative or the negative...I'll just have to fight my way over to the affirmative and hope the other guys haven't thought about it yet, and so don't realise just how impossible the negative is to argue.

    Perhaps I could argue that very very soon we will be able to engineer ourselves, and it is at this point that evolution will stop. We will deny the natural world control over our genes etc and start controlling the movement of all genes. Thus halting genetic drift and with it 'Evolution'.
     
  7. Jul 30, 2003 #6

    selfAdjoint

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    Whatever our circumstances may be in the modern world, variation in our genes keeps happening, and our environment is still selecting some who leave more descendents than others. So the mechanisms of evolution are still under way, with what ultimate result we cannot say.

    Many social thinkers worry that the more prosperous people get, the fewer children thay tend to have, on the average. This means that over the long run the prosperous (sometimes characterized as "intelligent") are evolutionary losers. Their descendents will be nothinmg much compared to the descendents of the still fertile poor.

    I think this is worrying too soon. We don't know what the future of the human race will be. Perhaps there will be another bottleneck and only a few individuals will be the ancestors of all the future human race. Nobody can say. But evolution is surely wending its slow way through our species as we post.
     
  8. Jul 30, 2003 #7

    megashawn

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    I mean, even if we have the ability to control our enviroments, this allows for less stressfull living, which would allow for more time for education, hobbies, etc. I'd say even if we've quit physically evolving, we could probably never reach a point where we quit mentally evolving. (which, I imagine is still physical evolution)


    I mean, the less we have to be out working or hunting, warring or what ever, the more time we have to do, well, whatever we want.

    I'd say not only are we still evolving, but we are slowly gaining control of our own evolution.
     
  9. Jul 31, 2003 #8
    If you think about it, the only way any species could stop evolving is either

    1) they stop reproducing

    or

    2) each member of the species produce an equal number of surviving offspring
     
  10. Jul 31, 2003 #9
    or

    3) they only reproduce after their own "kind"
     
  11. Jul 31, 2003 #10

    LURCH

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    Perhaps you could use the difficulty of measuring evolution as a wedge. Evolutionary biologists sometimes say (said, actully; you don't hear this much nowadays) that the process of human evolution is happening so gradually that it can't be measured.

    Modern science is all about the measuring. We can measure angles down to a billionth of a billionth of a degree, make measurements of time and space to such fine subtlety that we can not distinguish between the two (but we can still measure them). Yet with all this precission, we cannot measure how the race has evolved since the beginning of recorded medical history. Cross-breeding and genetic drift, sure; but no evolutionary trend. Since in science no measurement = no validation, you might get some points with that one.

    (does anybody swallow that load of garbage?!)
     
  12. Jul 31, 2003 #11
    Another God

    Is evolution currently happening to humans? This is easy to answer. Take a look at your parents and grandparents. Are you an exact duplicate of any of them? I doubt it. Most likely you will find that you have certain traits of each.

    I would, however, suggest that we are mostly beyond one facet of evolution, that being natural selection. The "purpose" of natural selection is to create a version of any given species which is safe from the common threats of its environment. We are safe from such. There aren't many things more dangerous than humans. Perhaps it is still in action, weeding out those who are killed by various diseaes, heart attacks, et cetera. But let's face it, there's no animals nastier than us, no condition of weather or such that really bothers us.
     
  13. Aug 1, 2003 #12

    Another God

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    Nah, I don't think we are beyond Natural Selection at all. Sure, we have levelled out the evolutionary terrain some, we are free to move from unlikely phenotype to unlikely phenotype without as severe a punishment as some other organisms, but there is still selection in action maintaining a whole host of necessary genes. Selection in process maintaining various character traits and removing others (people who, say, uncontrollably **** on everyone they meet probably won't have many offspring). There is sexual selection. There is a form of selection for probably the first time in natural history, where a class of humans are simply "Choosing" to not have children. This is selecting against that type of genotype.

    Resistence to bacterial infections, resistence to Viruses, cancer resistance are all under the scrutiny of selection. Heart 'disease' is even under selective pressure. As these diseases quickly become the largest killers in our society, our society is weeding out the people who succumb to them and creating hosts of people who don't. It's a gradual process, but it is happening.



    So yeah. Here again is my problem. I can present pretty much every argument concievable For Evolution still occuring, and just about no arguments against it....
     
  14. Aug 1, 2003 #13
    When I hear the quetion "Are humans evolving?" I often take it to mean evolving in a particular direction; that particular characteristics are being selected for and others are being selected against. If this is what you mean then I think that a case could be made that we are not.

    If you are instead suggesting that humans are evolving in the sense that individuals are subject to selection pressure and differential reproduction then obviously we are evolving. All life is evolving in this sense even if it's at hasn't really "evolved" for millions of years eg. the coelacanth. I would say that the principle force involved in human evolution would be stabilising selection.
     
  15. Aug 2, 2003 #14
    I think that certain populations are evolving, that is by your suggestion of being selected against. It's not some grand morphological change, but considering how many millions of Africans are contracting HIV, most will be dead, but there's got to be at least a few with natural immunities.

    But I think you've got to look at something else besides selection. Travel is so easy nowadays that there are a lot more people with different national heritages. Take my Scottish/Japanese friend for instance. There's a lot of new phenotypes out there. So genetic drift is a serious consideration.

    And giving how quickly humans have ****ed up the environment, antibiotics, etc. we'll have to worry about all kinds of selection real soon. Biologically speaking.
     
  16. Aug 4, 2003 #15

    Phobos

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    A.G. - The best I would expect is that human evolution has recently slowed (time of 'stasis' perhaps) due to our global coverage & transportation technologies. I.E., we don't have many significant isolated populations anymore in order to affect larger differences. But I don't expect that to be a permanent condition (and they're still be small changes in the population during that time).
     
  17. Aug 4, 2003 #16

    Phobos

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    That's still evolution (so called "microevolution"). For example, if you think a single wolf "kind" was aboard the Ark, and that kind spread across the world and developed into the gray wolves, arctic wolves, timber wolves, etc....that is still a speciation event(s) that qualifies as evolution. Actually, evolution doesn't even require speciation...just statistical changes in the frequency of alleles (expressed genes) from generation to generation. Your concern, I assume, is macroevolution (from one kind to another). But I don't want to get off on a tangent here...
     
  18. Aug 19, 2003 #17

    DrChinese

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    Taking the negative side:

    Obviously the forces of natural selection and random mutation are still at work. But is there any "net" evolution considering mutations which die out?

    Each of us has different DNA, even identical twins do not always have 100% identical DNA (considering replication errors). So what is the precise definition of human DNA?

    The issue presumably is whether a new genetic mutation common to all humans could develop. And to this, I believe the answer is NO. The population of humans is too large, and even over a very long period of time I am not sure it would be possible in humans.
     
  19. Aug 19, 2003 #18

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    Er... does evolution even work like that? I would think a more probable scenario is that the differing conditions (one might imagine H G Well's the Time Machines's Eloi and Whateveritsnameis) would create a greater divergence within the species, and then we get competition both in genes and overtly, and so we have one dominating and decreasing the prevalence of the other. I don't really imagine that whole populations just uniformly change.

    As to the question... Gee... devil's advocate. I suppose at some time you have to define a benchmark at which something is evolving or not, and you can set us as not evolving by definition. Maybe.
     
  20. Aug 20, 2003 #19

    Another God

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    Well, anyway, the debate is next week and I am on the affirmative side after all.

    Turns out the affirmative isn't quite so certainly guaranteed going to win as I initially though. As long as humans can control our environment forever, and sexual selection is largely driven by cultural pressures (media etc), then the only selective pressures are purifiying pressures (ie: The pressures which make us keep what we need to stay alive/function practically), which means we won't be evolving at all.

    I can't imagining us maintaining absolute control over our environment though. One day, some virus will get through and strike nearly all of us down before medicine can react. A commet will get through our defences. We will colonise other planets and it will create situations we can't control. We will run out of food. We will run out of space. The earth will flood. Bill Gates will buy out a political region, raise an army and kill all 'Jocks', thus providing a selective pressure to be a nerd.... Etc

    Any number of unforseen circumstances could arise, and selection will begin once again, and our massed numbers of variety will be selected against.
     
  21. Aug 20, 2003 #20

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    Erm... there are always some form of selective pressure. Like a selective pressure nowadays to be slim (or not). And it's always useful to be smarter... sort of.

    And I really don't think we have an absolute control on our environment at all...
     
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