Need examples of Modern Evolution in H. sapiens

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Discussion by: evolvettu

Good afternoon all,

I am writing a paper on the modern evolution taking place in humans to address the questions by most creationists; "If humans evolved, why arent they still evolving?" As we all know, they are! The book I am using now as a source is called 'The 10,000 Year Explosion', by Cochran and Harpending.

Please feel free to name off or list anything you think would make a good case in my term paper. Sources and authors would be much appreciated! Thank You!

 

38 COMMENTS

  1. “If humans evolved, why aren’t they still evolving?”

    6,000 years is the twinkling of an eye in evolutionary terms. Maybe that’s where the confusion comes from.

    But I’ll start with the immune system, for better or for worse.

  2. One thing to mention – I’m not sure if its relevant though – is that humans are at a point now where they don’t really need to evolve. We now have all the technology to do whatever we were unable to do in the earlier stages of our evolution. If ever we need to grow wings over millions of years, we wouldn’t because we now have planes. If we couldn’t reach fruit from trees, we’d grow it in the ground instead. Humans have evolved to the point that instead of evolving too much now (we are probably still evolving and like Papa Lazaru said, the immune system is obviously changing over time) we are spending our time ‘evolving’ our technology.. I don’t think that sentence made sense but you get the point.

  3. Humans are not evolving? Evolution at it’s most succinct is ‘change in gene frequency over time’. Hence every population of organisms alive (including humans) is evolving. Read some Dawkins!

    • In reply to #5 by rzzz:

      Humans are not evolving? Evolution at it’s most succinct is ‘change in gene frequency over time’. Hence every population of organisms alive (including humans) is evolving. Read some Dawkins!

      I feel like I shouldn’t have written that we are probably still evolving. We are definitely still evolving – it’s just that we are doing what we can to make technology provide us with, for example, the longer legs or the better eye sight we aren’t waiting millions of years for.

  4. Sickle-cell disease — a mutation that greatly reduces the effects of malaria on the host. It’s a change of the gene coding hemoglobin. It is becoming more and more widespread, for instance in Africa or Southern America, for obvious reasons.

    tibetans blood

    Google James Harrison, the blood donor.

    And these are just positive mutations. Every genetic disorder, hemofilia, phenylketonuria, albinism, etc. — these are all examples of mutation in the human genome. Sure, they are selected against by the natural selection, but they support evolution.

    • In reply to #6 by moebius:

      Sickle-cell disease — a mutation that greatly reduces the effects of malaria on the host. It’s a change of the gene coding hemoglobin. It is becoming more and more widespread, for instance in Africa or Southern America, for obvious reasons.

      There are also some people who are resistant to HIV.

      Our variation in skin color is a good example of variation that let people adapt to different regions of the world and the amount of sunlight received there.

  5. Disappearing wisdom teeth? In general, mandibular size, along with the number and size of individual teeth, has been decreasing since the Neolithic and before. Some people have wisdom teeth, some people never get them, and in others they don’t grow in quite right, which certainly could have been a life-threatening condition in the era prior to modern dentistry. This is exactly the kind of phenomenon you would expect to see in an evolving population.

  6. Hi evolvettu,

    Jerry Coyne has a post on his site entitled ‘Are humans still evolving?’

    So women, at least, are getting shorter, stouter, and reproducing earlier and over a longer period of time. This is evolutionary change. Based on this study, we can tentatively say, with more assurance than I used to, that yes, our species is still evolving.

    http://whyevolutionistrue.wordpress.com/2009/10/24/are-humans-still-evolving/

    A recent post on WEIT also linked to a BBC panel discussion: ‘Human Cultural Evolution Versus Genetic Evolution (Episode 1 of 2)’

    Steve Jones, Steve Pinker, Kevin Laland, Steve Stearns, and my own Chicago colleague Anna di Rienzo.

    http://www.bbc.co.uk/programmes/b0135z1m

    Enjoy!

  7. I am writing a paper on the modern evolution taking place in humans to address the questions by most creationists; “If humans evolved, why arent they still evolving?” As we all know, they are!

    It is one of the problems with creationist ignorance, that their bronze-age biblical thinking concentrates on humans (and some related vertebrates) to the neglect of the wider spectrum of life.

    Humans are a poor choice for observation by humans, as we are unlikely to survive long enough to personally observe more than two or three generations at most. Given that evolution has only been studied seriously for less that 200 years, this is not enough generations for contemporary studies of the present populations to progress very far in illustrating points to non-specialists.

    To demonstrate evolution, without resorting heavily to genetics or fossils, short life-cycle organisms with many generations of large numbers of offspring are required – This allows us to plot readily observable evolutionary changes and phenotypic diversity. (eg. Insects and plants)

    Humans have low and slow reproduction rates, in comparison to most plants, animals, and single-celled organisms.

  8. Disappearing wisdom teeth? In general, mandibular size, along with the number and size of individual teeth, has been decreasing since the Neolithic and before. Some people have wisdom teeth, some people never get them, and in others they don’t grow in quite right, which certainly could have been a life-threatening condition in the era prior to modern dentistry. This is exactly the kind of phenomenon you would expect to see in an evolving population.

  9. Why aren’t humans evolving? …because the time-scale across which humans (and other species) are being examined are too short for evolution to make significant changes.

    Other posters have suggested a number of mutations currently occurring to the human genome, but I would like to point out the one effecting me: I have the pale skin of a European. This is a micro-evolutionary mutation caused by environmental factors

  10. I think I read somewhere that the general consensus amongst experts is that human evolution is still taking place. I’m not an expert in anything, but I do sometimes wonder if the modern, (western), environment has removed – or significantly reduced – the power of natural selection to induce change.

    Taking HIV/aids, for example: if there were no such thing as anti retroviral drugs or combination therapy, isn’t it likely that natural immunity would confer a survival advantage and therefore become more widespread? In other words our medicine and technology enable US to choose who survives, and therefore those born with innate immunity do NOT have an advantage and such immunity is not forced to become more widespread.

    My point is that to a large extent our mental ability has removed us from the survival game so that many of us can survive whom nature would otherwise have casually culled, (as a severely disabled man, I include myself in this group).

    As far as the shrinking mandible is concerned, is it conceivable that the trend was begun under normal evolutionary pressure but is somehow still ” rolling”, even though the rise of dentistry has removed the pressure?
    Remember: I know nothing – I’m just thinking aloud!

  11. This development of the immune system that makes certain genetic groups immune or less affected to certain diseases. For an example you could speak about how the native Americans were decimated by western diseases as they were not protected.

  12. The ability to digest milk as an adult is a recent ability that evolved in the last 5000 years or so. Google “when did digesting milk in adults evolve”. Note that this ability is not uniformly distributed through out the global population.

  13. Check out Jared Diamond’s “The World Until Yesterday”, in particular chapter 11 (Salt, Sugar, Fat and Sloth). In part it details an explosion in the rates of diabetes and hypertension in the island populations in Malaysia (may be wrong about the location, haven’t read the book recently) after the introduction of Western style diets; the rates have been falling recently after ~40 years of steady climb. Not confirmed, but Diamond’s guess is that those most susceptible to these are dying faster than they can breed. I’ve mangled the details, but that’s the thumbnail version.

    On a side note, @papa lazaru, the number of years isn’t really important. The evolutionary process runs at a generational scale, not on the basically arbitrary divisions we humans use to mark time. Essentially, your rate of evolutionary change is entirely dependent on your species; if you breed fast and die young, evolutionary changes show up quickly (think fruit flies). Conversely, if you have long periods between generations, the rate of change slows down. We monkey folk have a new generation every 15 to 30 years, so the rate of change is relatively slow for us.

  14. HIV/AIDS might provide an example to think about. (Oops, I see that #7 and #14 have mentioned this already so you don’t need my essay. I expect the reference in #7 covers any facts I have. You could look into HIV in chimpanzees for comparison and consider the potential for future evolutionary parallels in humans. I think HIV only went beyond localized and limited infectious problem for humans in the 20th century.

    By the way, isn’t the point of doing a research report that you do the work of locating sources and developing ideas yourself? Make sure you footnote your paper identifying this discussion topic as a source and give proper credit to each of the user(id)s for information or ideas you use that they provided. That’s what proper researchers do. ;)

    Sorry, but I’m just not familiar with the objectives of modern education; is it to learn how to do the work oneself or to figure out how to get other people to do it?

  15. Two suggestions for which I regret I don’t have references:

    1: Pale skins – the mutation for this is recent and took over very rapidly in the human population moving north in Eurasia from Africa. When they left Africa the first modern Eurasians were black. They remained black until the mutation for pale skin arose and gave one person, and their descendants, a huge advantage – they didn’t get rickets. Those who walked all the way to Australia were black and their descendants are black to this day.

    2: Adult lactose tolerance: modern human populations differ in this greatly.

    There must have been huge natural selection in premodern times [= up to the day before yesterday] in resistance to a whole range of infectious diseases, which killed c. 50 % of children before they became adults.

    The question to ask yourself is not about ‘evolution’ but about ‘natural selection’ which is what Darwin discovered. If it’s true that modern humans aren’t evolving – what is the evidence for this assertion? – perhaps it is untrue – it must be because natural selection is much weaker now than hitherto because infant and child mortality is much lower than it was. Look up the numbers and put them in.

    Eurasian infectious diseases were fatal to New World humans because they had not evolved resistance to them because they were not previously exposed to them. Look up the very shocking history and put it in.

  16. The human population is in flux as always!!! Consider googling statistics concerning wisdom teeth. It seems that they are “on the way out” as far as their evolution is concerned. They are going the way of the appendix; becoming vestigal and now actually disappearing.

    We have been barraged for years now about how fat we are getting. As a matter of fact, car companies have had to expand the seats in compact cars by two to four inches over the past three decades or so; to accomodate our fat asses!!!

    Another huge piece concerns certain recessive diseases in humans conferring selective advantage for the heterozygote. Ever wonder why cystic fibrosis, Tay Sachs disease, Sickle cell anemia (and more) persist in the population?? Well, in each case there is a naturally occurring disease (malaria in the sickle cell example) and the homozygous dominant is susceptible to the malaria, the homozygous recessive has sickle cell anemia, BUT the heterozygote gets neither. it is called the heterozygote advantage and there are many awesome examples — google it!

  17. Wouldn’t cultural evolution be considered a large factor going on today? Men’s genetic code still wants us to mate often and with as many females that will accept us, while women’s genetic code still influences their choice of males they will mate with. The biggest and strongest (and possibly smartest) males will be more successful attracting the most beautiful child bearing females. In other words, evolutionary forces from thousands of years ago still influence our mating choices today?

  18. As soon as we’re no longer subjecting ourselves to the thinning effects of natural selection, by taking care of our weak, ill and elderly, we’re no longer evolving in the same way we did before. Now we are artificially selecting ourselves.

    • In reply to #22 by brighterstill:

      As soon as we’re no longer subjecting ourselves to the thinning effects of natural selection, by taking care of our weak, ill and elderly, we’re no longer evolving in the same way we did before. Now we are artificially selecting ourselves.

      But the periodic collapse of weakened empires, weakened economies, resource depletion, wars, and famines, probably sporadically compensate!

  19. Alcohol.

    I note that the ability to tolerate/metabolize alcohol varies over different branches of the human population, and that this appears to be genetic, like skin color. Would that not be a fine example to explore?

    Some populations exploited the fact that fermented drinks kill water-borne diseases, and their descendants are much better able to “hold their liquor” than those descended from other lineages, where alcohol was not used as a beverage disinfectant.

    Discuss.

  20. you are evolving is the simple answer

    the Lensky experiment took 50,000 generations of bacterial evolution (quicker due to horizontal gene transfer). that’s about 1,000,000 human years. the enswer to creationists is stop being so impatient and just try to imagine how much trouble they’ll be in heaven trying to behave for eternity when they can’t even grasp the concept of the relatively minute level of geological time? god will be fed up with their whining after a year or 2 i reckon and with no one bothered to keep them entertained they’ll soon realise that heaven and hell are both a bit boring. i suggest in preperation for eternal praising they should all attend a course in understanding deep time. might cure their religion as a by-product

  21. like some have said.. our immune system is certainly evolving. Another: in Holland for instance we are a great deal taller than our ancestors were just a couple of hundred years ago, which is more than just a centimetre or two.. evolutionary change based on better dietary intake…our brain is still growing due to the fact that some of us learn more and more every generation. and these creationist should know that evolving doesn´t mean that we change into a different species overnight, that will take quite a bit longer, thousands and thousands of years, not just the few thousand years that they believe we have been around..

  22. That’s a good one. Can’t think of anything except I believe the size of the Brain has been increasing bit by bit. One other thing that comes to mind, is the Knife was invented about 2.5 million years ago, but nothing new was invented after that for about 5,000 years. Read that somewhere.

  23. I’m rather curious about the effects of bacteria, parasites and viruses on our DNA. We know that chicken pox is persistent in the body as evidenced by shingles, but we have yet to observe what else it does. Maybe it accounts for a preference in food type or color or other behaviors that are regarded as merely human. We may find out in the future that these organisms are behind our “individualism.”

  24. I think it is an error to take seriously any question about evolution posed by creationists of the YEC variety. They do not understand the word “evolution”. They are not interested in one species (their own, in this case) displaying modifications as adaptation to the environment. Their terms of reference are so flawed that they will only be satisfied by proof that one species undergoes so many survival adaptations as to become a separate (new) species.
    And they don’t really know what the word “species” defines.
    They see that homo sapiens continues to be homo sapiens, ergo – there is no sign of evolution.
    The question “If humans evolved, why aren’t they still evolving?” is about as silly as saying, “I’ve been watching this grass for 30 minutes and it is definitely not growing.”
    evolvettu – continue your research for your own, personal benefit by all means, but don’t ever imagine that you will be able to satisfactorily answer that creationist non-question.

  25. We are symbionts. The number of parasite cells (symbiotic bacteria) that live in our bodies outnumbers our own human cells by 10 to 1 (based on the number of cells – not the mass or volume). The evolution of those parasites is bound to have had an effect on our own evolution. However, I wouldn’t go there in your particular report. Like any report, the challenge isn’t filling the pages; the challenge is limiting its scope, or it will quickly expand to unmanageable proportions.

  26. As the amount of time humans have had to evolve over the past 10,000 years is equal to roughly .00000025% of the time that all organic matter has had to evolve, I think your premise is, if not flawed, then certainly faulty.

  27. I guess I arrived late. first, really sorry for my english, I’m a spanish speaker, so I’ll try my best. I’m not a biologist yet, but my couriosity for evolution gives me the oportunity to try to answer your question. Evolution is a gradual process as Richard Dawkins mentioned in his books, it must be gradual, so it is possible that there are a lot of thing that could are evolving but we can’t watch it. However there are wonderful examples that Richard D, mentioned in his book of Evolution’s evidence, like: The size of elephant tusk, E.coli bacteria of Lenski, and the lizards for a islands that I forget the name and guppys fishes. They are amazing example of evolution even for the time that evolution requieres, it is really short. Now, I’m not aware of evolution process of Human, people say tooth loss, appendix. I’m not sure if they are example or not, Human are travellingall the time, if you are waiting for a change we need variety, and something to replace, human with knowledge and tecnology solves their needs, so that argument that our brain is getting bigger sound very right. Finally my intention is that, they are other examples where you can find evolution process, I mean other species. Sorry for my english. and Succes!

  28. According to me what happened in the case of the Human Being was a Mutation NOT evolution. Usually one species follows the other in an intelligent fashion, instead a branch of primates started to transform themselves in a grotesque fashion. Human Beings are also notably bad, so this would indicate that they did not progress in a natural fashion at all, and instead they can be likened to a form of cancer. The fact that they are threatening the survival of the Earth with their same existence is a confirmation of the “cancer ” theory according to me. No other species of beings threaten their environment , and instead usually they contribute to the healthiness of their environment. So, a mutation occurred, not evolution.

    • In reply to #37 by giuliano753:

      According to me what happened in the case of the Human Being was a Mutation NOT evolution.

      I think you need to read up on the subjects of mutation and natural selection.

      Usually one species follows the other in an intelligent fashion,

      There is no “usual progression” or “intellegent fashion”. – Only successful future generations or extinction of particular genes.

      instead a branch of primates started to transform themselves in a grotesque fashion. Human Beings are also notably bad, so this would indicate that they did not progress in a natural fashion at all,

      Nature does not make “good” or “bad” judgements.

      and instead they can be likened to a form of cancer. The fact that they are threatening the survival of the Earth with their same existence is a confirmation of the “cancer ” theory according to me. No other species of beings threaten their environment , and instead usually they contribute to the healthiness of their environment.

      Many species are so virulent that they exhaust the resources they depend on for life, and then that population dies out, of the whole species becomes extinct. It has happened many times.

      So, a mutation occurred, not evolution.

      Mutations are part of the evolutionary process not an alternative to it. Some mutations create radical changes, others are passive and largely irrelevant.

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