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Josh S
  • Josh S
  • Washington, MO
  • United States

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What is an example of a random genetic mutation in humans that has proven to be beneficial?

Well, basic natural selection states that random mutations, while usually negative, can sometimes be positive and will help the creature successfully reproduce. We atrribute this to how we ourselves became our species. We classify ourselves as animals, and genetically speaking, we still show many mutations, approximately ~2.5×10−8 mutations per base per generation. With approximately 100 billion humans ever having lived on earth, shouldn't we have seen or heard of at least 1 reported beneficial mutation?

Now of course it would be hard to document someone with a beneficial mutation 20,000 years ago, but what about in the past 500 years?

So have you ever heard of a positive mutation that has been seen in humans? If yes, what was it?

Sources:
http://en.wikipedia.org/wiki/Mutation_rate
http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx

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    Oct 19 2012: Casey is right, we are in fact a string of beneficial genetic mutations, so there are litelally billions of such mutations along the histroy of humans forming. It is how we formed.But if we were to exemplify some that took place recently, as in after we became what we are today, here is a cool one:

    During the black plague, there was subset of the population that presented a genetic mutation that rendered their T cells immune to the plague because they lack the gateway that permits the plague to invade the cell. So basically they can be injected with live culture and the plague will simply die inside them, because it cannot attack the very specic cells it attacks in general population. Interestingly enough, because the plague attacks the same cells as HIV does, these people and their descendents who were lucky enough to inherit the mutation are also immune to HIV. They will never get it, even if they are injected directly with a high dose of the the virus.
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      Josh S

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      Oct 19 2012: Thank you! that was a great example that i was looking for!
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    Oct 19 2012: How are we not a beneficial mutation?
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      Oct 19 2012: You've closed the discussion.
      Good point.
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      Josh S

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      Oct 19 2012: Unless you are saying that we are already the perfection of nature, then there should still be genetic mutations that can be beneficial.
      • Oct 19 2012: Yes, there still are beneficial mutations. But the point stands. We are the result of lots and lots of beneficial mutations. You had other examples above, like the one allowing some individuals to resist HIV. Observe however, that for a mutation to be considered beneficial there is a circumstance. If HIV and the plague had not existed, these mutations would be considered just variation. Variation with no major consequence. So, look around you. Notice that there's enormous variability just in people. Here's the take-home-messages:

        1. any of that variability might be a beneficial mutation in that it could be the one allowing a subpopulation to withstand some environmental challenge.

        2. try and understand that the existence of so much variability proves that a good amount of mutations are not harmful, thus your assumption that most mutations are harmful is wrong.

        So, when you ask about beneficial mutations, you should understand that "beneficial" depends on the circumstances.
      • Oct 21 2012: You assume biological evolution has a direction (perfection), but it doesn't.

        Consider Sickle Cell Anemia. It is common condition and associated with certain populations living in locations where Malaria occurs. It turns out those with this condition are provided a survival advantage to those not having this condition and exposed to Malaria. The physical changes Sickle Cell Anemia brings about in red blood cells shape, which is a significant health concern, proved to be beneficial in helping individuals with this condition survive malaria. It clearly explains why Sickle Cell Anemia is relatively common in certain populations.

        A clear example of taking the good with the bad when it comes to survival of the fittest.
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    Oct 20 2012: Is not our existance so far despite of all natural barriers /challenges aleady the greatest example of benefit of mutation?
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    Oct 19 2012: Hi Josh,

    Here is a link to a fragment of a History Chanel program where the work of Dr Hansell Stedman is discussed. He stumbled on some genetic mutation present in all humans that is directly related to some type of muscular distrophy. In particular, this part of the human genome is very distinct from that of our closest relatives (the chimps)

    Lo and behold, the muscles that result affected are the main muscles that closes the jaw... and the result was that, lacking those strong muscles, the bones of a human skull took much longer to solidify, allowing for a long period of brain growth compared to the time a chimp brain can grow within its skull

    https://www.youtube.com/watch?v=g0D_k4lYrdo

    i hope you enjoy it

    cheers
  • Oct 20 2012: Just a general observation,

    We have modified our environment so effectively that we have significantly reduced the natural selective pressures we once were subject to and consequently that driving force of biological evolution has been altered. There was a time not so long ago when humans would commonly die in their twenties and very often at birth. Now people routinely live into their seventies and eighties. No one knew what a microbe was or thunder for that matter. There was minimal protection from the hostile environmental conditions.

    That is not the case in more recent history due to our cultural evolution that came about by our biological evolution. Humans live much longer healthier lives now. We have protected ourselves from the selective pressures of the past hostile environment in numerous ways. Ample and nutritious food, improved shelters, medical and dental care including medications for numerous ailments, improved housing, sanitation, and on and on and on. What that means is we have tamed our environment to the extent that what would have been a beneficial variation of a trait in the historic past vie genetic recombinations and/or mutations it is now masked because the selection pressure has been removed or significantly reduced. So these individuals are not weeded out. The result is genetic loading reflecting considerably less selection and a suspension or delay in the dynamics of biological evolution in the human populations.
  • Oct 19 2012: Stefan already mentioned the anti-plague/anti-HIV gene, Gordon mentioned the lactose tolerance gene. I myself can think of the sickle-cell disease gene, that protects against malaria (but causes sickle cell-disease which is fatal in your 40s or 50s), the genes that allow (most of us) to not be allergic to dogs and be immune to the pests they carry, the gene that gave the white conquistadores heightened resistance against all those diseases that devastated the native Americans, and of course there's the giant elephant in the room: humans were all brown at first, but then European and Asian phenotypes arose among the humans that left Africa for other regions of the planet with different climates.
  • Oct 19 2012: the only one that comes to mind is the mutation that allows some humans to digest milk.
    Although I don't drink it I do like it in my cofffee and I would prefer not to vent plasma from my port nacelle after eating cereal.
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    Oct 19 2012: If you are ever in DC, check out the Smithsonian's clothing collections and see how much taller we all are.

    The Netherlands has the biggest growth, having come from one of the shortest people to one of the tallest.

    Girls are entering puberty earlier.

    Apparently, genetic adaptation that allowed one to either get the plague or not get it has been documented.
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      Oct 19 2012: I think both of those examples are due to better nutrition and health care rather than genetics.
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        Gail . 50+

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        Oct 19 2012: Perhaps, but once the genetics change because of better nutrition, the genetics are changed. If a well-nourished mother causes the embryonic genes to recognize the abundance of nutrition, they can select for tallness based on availability of food. Once genes have selected for tallness, then the genes transmit tallness to future generations.

        Quote from "Scientific American": Peter M. Visscher of the Queensland Institute of Medical Research in Australia recently reported that the heritability of height is 80 percent, based on 3,375 pairs of Australian twins and siblings. This estimate is considered to be unbiased, as it was based on a large population of twins and siblings and a broad survey of genetic markers. In the U.S., the heritability of height was estimated as 80 percent for white men. These estimates are well supported by another study of 8,798 pairs of Finnish twins, in which the heritability was 78 percent for men and 75 percent for women. Other studies have shown height heritability among whites to be even higher than 80 percent.
  • Oct 19 2012: This is constantly happening. These changes obviously range from bad to not consequential or good. less than 50,000 years ago Northern Europeeans were lactose intolerent. What sort of time frame for Indians(in India) or the Masai in Africa Who knwos but that isn't the point. What do we want to look at - ability to tolerate Malaria ability to handle alcohol propensity for diabetes Ability to survive on a very limited consumption of calories etc. etc. etc. People vary as certainly isolated groups do