Have we stopped evolving.

Discussion in 'Biology & Genetics' started by Halo, Oct 15, 2002.

  1. Halo Full Time Nerd-Bomber Registered Senior Member

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    If humans evolved from the simplest substance over the course of 4 billion years they must have done it through mutations, right? That's all fine and dandy but if you look at todays society how willing are we to accept this? Take for instance a person born with 6 fingers. Genetic mutation. The body has evolved and found that it needs 6 fingers to better operate it's daily tasks. How is this looked upon in society. Most people might say he's a freak because he is not part of the norm. He doesn't have 5 fingers like everyone else should. But if we were meant to evolved then shouldn't we be more accepting of these genetic variations? At what point in time will we all have 6 fingers? Let's say the 6 fingered man decides to get the 6th finger surgically removed so he can be just like everyone else. Then we would have set ourselves back hundreds of thousands of years because we were supposed to evolve in such a way but we don't. Aren't we just holding ourselves back?
     
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  3. Stryder Keeper of "good" ideas. Valued Senior Member

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    You just have to look at the differences of the human brain to see one form of continuing evolution. Not to forget to mention the reason that that people have different colours for eyes, hair and skin is just another evolution formulated in conjunction with the peoples surroundings. (thats' why we are all Human).

    The continued Evolution of Science and even technology will continue our evolution, in fact our evolution is move beyond just our bodies and extending to the tools we use and the way we do things.
     
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  5. grazzhoppa yawwn Valued Senior Member

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    A past thread as looked at this topic with quite a few quality responses...most agreed that we will not naturally evolve, in the sense of a simple organism turns into a complex one. Humans will now determine their genes through science and manipulation, sort of enhancing our species, but not necessarily evolving it.

    Look here for more.

    I don't think cutting off a 6th finger would set us back in natural evolution, because you aren't taking the mutated gene that gave instruction for the extra finger. Humans are beyond natural selection because we can control our health and we take care of everyone (in a sense), we don't let nature take its course.

    One question is whether this is all correct because humans have been on the Earth for a relatively short time to evolve.
     
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  7. chroot Crackpot killer Registered Senior Member

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    Halo,

    You don't understand evolution.

    The dominant mechanism in evolution is the constant generational cycle, in which individuals select mates, mix their DNA, and produce offspring. The 'natural selection' of who gets to mate is what drives evolution.

    Mutation is just a ripple on the surface. The many biochemical systems of life are very fragile - very nearly all mutations are immediately fatal to the organism. Only once in a blue moon will a mutation benefit the organism.

    Let's imagine that you're at sea level, but you'd very much like to be on a mountaintop. What do you do? You begin walking in the direction that best leads "up" from your current location. You begin climbing the nearest hill. Imagine that you measure your success by your altitude: the higher you go, the better off you are. So you can describe your environment by a "fitness landscape:" the higher, the better.

    This is what genetic crossover does: it gradually produces organisms better and better fit for their environment. The population slowly climbs the hill toward the "best" mix of the genetic traits present in the gene pool.

    There exists a finite number of genetic traits in the gene pool of any population of organisms. Therefore, there exists a finite number of different combinations of those traits.

    Eventually you get the top of the nearest hill. You've reached a "local maximum." The population has settled upon the best mix of the traits contained its gene pool, and evolution has "stopped."

    Now, mutation is something like random teleportation in a video game: every so often, an offspring will end up radically different than its parents through some critical mutation, and will be "teleported" to a different part of the fitness landscape. Most often, the mutated organism will not find itself in a better position than its parents, but every now and then, it'll wind up on an even bigger mountain -- with more room to go up. The new, mutated genetic trait enables evolution to continue moving up the fitness landscape. Eventually, all of the members of the surviving population will express that new gene... and the population will arrive at another local maximum, another hilltop.

    In the case of the six finger man, his body didn't "evolve" and "decide" that mankind needs six fingers. A point mutation occured in one of his Hox genes, and he grew six fingers. This doesn't necessarily make him any more or less fit than the rest of the 5-fingered population. In fact, because he'll likely have trouble finding a mate, it means he is less fit. Like I said, mutations almost never result in benefits to the organism.

    The "punctuated equilibrium" model, as it's called, embodies all of these features. A population of organisms reaches an equilibrium with its environment. In such an equilibrium, natural selection has found the optimal mix of the genetic traits in the gene pool. Then, blamo!, some critical point mutation happens, the new organism has some particularly wild new trait, and it happens to be advantageous. In the case of the well-studied black and white moths, the first black moth had an immediate advantage. It was successful in finding mates, and spread its new gene to its offspring, who were likewise very successful. Very, very quickly, the entire surviving population turned black. That's the "punctuation" in "punctuated equilibrium."

    Our own genome shows a huge amount of evidence for this kind of evolution. I don't remember many of them, though, so I'll have to go look up the specifics again.

    - Warren
     
  8. paulsamuel Registered Senior Member

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    882
    reply to chroot

    nice post warren. I would appreciate if you would pass on any refs you find regarding evidence of P.E. in the human genome. Thx, Paul
     
  9. Clockwood You Forgot Poland Registered Senior Member

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    4,467
    We are still evolving. 2% of mankind is immune to aids. That 2% will be more prolific than the remaining population by a slight degree. That 2% will become an ever-larger percent until aids is no longer a factor.

    Similar things are happening all the time. Another example is what is considered beautyful. Those considered so gain healthy mates more easily and thus have more offspring. Thus each generation becomes more beautyful. (until the ideal of beauty changes.)
     
  10. grazzhoppa yawwn Valued Senior Member

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    1,277
    I would guess, we would find a cure/vaccine for AIDS before most of the world population was immune to it...then a new strain of AIDs will peak it's ugly head out...and we would start over again....humankind medles too much with nature.
     
  11. Clockwood You Forgot Poland Registered Senior Member

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    4,467
    How about the ability to have more children faster? A shorter gestation time and weaning period would do that.
     
  12. axonio98 Banned Banned

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    101

    What's important in evolution is an better reproductive capacity. If a 6 finger pearson, or a supergenious doesn't have sufficient juice he won't pass is genes to the next generation.
     
  13. Brett Bellmore Registered Senior Member

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    At the present moment, we're not only evolving, but evolving very rapidly indeed, due to a radical and recent change in our enviroment: Modern medicine.

    The down side of modern medicine is that it enables people to survive many harmful mutations, and reproduce. So the human genome is filling up with garbage. That's a form of evolution, even if it's not good.

    The up side? To give just one example: Increased intelligence. There's substantial evidence that the average IQ of mankind was a result of an equilibrium between the selective advantage of greater intelligence, and the selective disadvantages of increased mortality during childbirth due to large headed babies, and increased resting metabolism rendering the more intelligent more likely to starve to death during hard times.

    But modern medicine has given us the C-section, among other things, enabling woman and child to survive the birth of larger headed babies. And modern agriculture has made starvation an unusual fate, at least in advanced societies. So the two greatest countervailing forces resisting the evolution of larger, more energy intensive brains have abruptly been removed! Even without further mutations, evolution is very rapidly going to increase the average IQ of mankind, as the relative frequency of genes shifts.

    Add to this that modern society makes high intelligence even more of a selective advantage, because we're mostly NOT competing on the basis of animal strength anymore.

    And this isn't just speculation. Ever heard of the "Flynn effect"? Even after controlling for every known confounding variable, the average IQ of people in developed societies has been increasing at an average rate of about 3 IQ points per decade for a century now! Only the fact that they've kept renormalizing the tests has disguised the fact that the average person of today would have qualified as a genius a century ago!

    http://pespmc1.vub.ac.be/FLYNNEFF.html

    In fact, the Flynn effect is profound enough to account, by itself, fr the observation that elderly people tend to have lower (Normalized.) IQs than the young. They're not actually getting stupider, their children and grandchildren are brighter! Because gene combinations which result in higher IQs are not being systematically eliminated from the population anymore.

    This is evolution, with a vengence! Isn't it exciting, realizing that we're right in the middle of one of those punctuated equilibrium shifts?
     
  14. pumpkinsaren'torange Registered Senior Member

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    2,159
    stopped evolving..

    no, of course we haven't....and, neither has any other living creature..
     
    Last edited: Nov 10, 2002
  15. Delvinity Registered Member

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  16. LionHearted Registered Senior Member

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    I think that civilization today is not as favorable for evolution as nature. If a mutation caused someone to be a better person, that person may not necessarily be more likely to reproduce. Someone who is addicted to every drug known to mankind, on welfare, never works, and is weaker and dumber than most of the population could have many children. Someone who is rich, smart, strong, clever, etc may have only a few children. Technology is also causing us to evolve in the wrong direction. There is no need to have strong legs to walk with because we have cars to take us everywhere. There is no need to be strong and fast because we don't have to hunt, we just need to go to the grocery store. Maybe we should start enforcing a minimum bench press, 40 time, and SAT score to have children. As the population would become increasingly stronger and smarter, we could raise the standards.
     
  17. paulsamuel Registered Senior Member

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    reply to lion

    you say these things because you don't know what evolution is.

    the three things necessary and sufficient for evolution are variation, heritibility, and selection. apply these three things to your thoughts on human evolution.
     
  18. TATABox Registered Senior Member

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    Mutation is a part of evolution, some people are more suceptible and others aren't. this can be carried through depending who the mates is, mutations are based on many things, DNA duplication, repair mechs (ligase), sunlight etc. Mutations are selected for depending on the environment. For instance, ask the question, what good is six fingers in today's environment, or webbed toes for that matter?
     
  19. paulsamuel Registered Senior Member

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    reply to TATABox

    What is your point??

    evolution occurs. it's worth noting that selection occurs at the level of the whole organism, not any particular character, like 6 fingers.
     
  20. Pollux V Ra Bless America Registered Senior Member

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    6,495
    Brett,

    About the IQ tests, I'm not sure that they're correct or represent the whole of our species, not only because I've heard that they don't accurately represent intelligence, but because only a minority of people in a small part of the world have taken them. There's a lot more humanity out there, in Africa and Asia (and Australia heheh

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    ) that haven't acquired the same access to western medicine as we people in the west have.

    But there are significantly noticeably effects of western medicine itself. For one, I believe that at the turn of the century there was a major population explosion all around the world, because people usually gave birth to large families of 10-12 children. They did this to ensure their families' survival, to combat various diseases and the etc. When medicine arrived, suddenly everyone was surviving the plagues and epidemics that would ravish the world. I'm not condeming modern medicine in any way, we're only experiencing a temporary problem with the explosion of humans, it won't be long before we leave our cradle and head for the stars.

    But back to the subject at hand.

    Are humans still evolving?

    Yes, I'd say that they are, but evolution itself, without genetic manipulation (of which we're starting to dab in) takes millions of years to "be noticeable," that is, larger or smaller organs, different bone structure, you get the idea. We've only had the idea of evolution around for a little over a century (I think?), that's 1/100 of the blink of the eye in evolutionary terms. It doesn't really matter though, give it a few decades before people are augmenting their bodies with technology beyond our wildest dreams.

    BTW paulsamuel,

    I watched a special on hermaphrodites in my Bio class a few days ago (we're going through early devolopment) that had been taped on PBS, it was about this "craze" in the fifties or sixties started by a man who I think was called Doctor Money...or something similar. Anyway, one of your colleagues at the University of Hawaii (I'm assuming), a Martin Diamond I think, immediately went against what this guy was saying, that boys who had lost their testicles could be raised as girls and then develop female organs with the proper hormones and family support. Eventually Money was disproved by Diamond.

    So just on the off-chance that you two know each other, tell him I say Hi.
     
  21. TATABox Registered Senior Member

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    Reply to paulsamuel

    my point is just to state that Halo was looking at evolution the wrong way, didn't i make that clear?
     
  22. paulsamuel Registered Senior Member

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    reply to TATABox

    and MY point is that you're looking at evolution in the wrong way, and didn't i make THAT clear
     
  23. TATABox Registered Senior Member

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    reply to paulsamuel

    how is looking at an individual character looking at evolution the wrong way? didn't darwin find that birds on one island had a longer beak than their couterparts on another island b/c they had to fish thier food out from holes that where present in the topography of that island vs. the other. Wasn't it the same w/ the Tortises, one group had longer legs b/c the leaves were higher?
     

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