Human Evolution Speeding Up

[Moonbeam]

Last month an interesting article was submitted to the Proceedings of the National Academy of Sciences regarding the acceleration of human evolution over the last 40,000 years. Here's the abstract: Recent acceleration of human adaptive evolution John Hawks, Eric T. Wang, Gregory Cochran, Henry C. Harpending, and Robert K. Moyzis Genomic surveys in humans identify a large amount of recent positive selection. Using the 3.9-million HapMap SNP dataset, we found that selection has accelerated greatly during the last 40,000 years. We tested the null hypothesis that the observed age distribution of recent positively selected linkage blocks is consistent with a constant rate of adaptive substitution during human evolution. We show that a constant rate high enough to explain the number of recently selected variants would predict (i) site heterozygosity at least 10-fold lower than is observed in humans, (ii) a strong relationship of heterozygosity and local recombination rate, which is not observed in humans, (iii) an implausibly high number of adaptive substitutions between humans and chimpanzees, and (iv) nearly 100 times the observed number of high-frequency linkage disequilibrium blocks. Larger populations generate more new selected mutations, and we show the consistency of the observed data with the historical pattern of human population growth. We consider human demographic growth to be linked with past changes in human cultures and ecologies. Both processes have contributed to the extraordinarily rapid recent genetic evolution of our species. And the full-text: http://www.anthro.utah.edu/PDFs/accel.pnas.smallpdf.pdf To summarize, it says that human evolution has increased at an amazing rate since the development of agriculture, 100X faster than before that event. This means that, contrary to what was previously thought, people are much different than they were 40,000 years ago, or even 1000 or 2000 years ago. Some recent changes: the ability to digest milk, and blue eyes in Europeans, and resistance to malaria amongst Africans. Another interesting thing is that the people on different continents are evolving more differences, so that instead of the races becoming blended, as most people assumed was happening, they are actually diverging. Some discussion on the subject: http://www.reuters.com/article/healt...rpc=22&sp=true Recent acceleration of human adaptive evolution http://www.physorg.com/news116529402.html http://news.nationalgeographic.com/n...olution_2.html

[Mystic7]

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[Scatterbrain]

Interesting but I wonder if that remains true nowadays, the more medicine and technology advances, the less natural selection we get right? Maybe now it's up to us to perfect genetic engineering and make our own evolution.

[Jeff777]

Interesting but I wonder if that remains true nowadays, the more medicine and technology advances, the less natural selection we get right? Maybe now it's up to us to perfect genetic engineering and make our own evolution. 2012

[Spartiate]

Interesting but I wonder if that remains true nowadays, the more medicine and technology advances, the less natural selection we get right? Maybe now it's up to us to perfect genetic engineering and make our own evolution. Evolving doesn't necessarily mean that we advance, just that we adapt to our environment. Future humans will probably lose more useless leftover features, like body hair, wisdom teeth, our appendix, etc. Another thing I heard is that our buttocks will get bigger since we all sit so much . Our brain capacity will also surely increase.

[Photolysis]

With all of the modern medical advances in the past hundred years or so, I'd say human evolution is more or less non-existent at the moment. An example is the continued existence of the cystic fibrosis gene in the human gene pool. Without modern medicine those who have the gene would almost certainly die an early death, and the gene would be eradicated. Likewise, a lot of other mutations no longer experience much selection pressure, so the human species as a whole will get weaker and weaker.

[Moonbeam]

Evolving doesn't necessarily mean that we advance, just that we adapt to our environment. Future humans will probably lose more useless leftover features, like body hair, wisdom teeth, our appendix, etc. Another thing I heard is that our buttocks will get bigger since we all sit so much . Our brain capacity will also surely increase. Some organs that were thought to be useless are discovered to have a function after all, including the appendix (reservoir for good bacteria.) I don't think that modern medicine means that people will quit evolving. The larger the gene pool, the more opportunity for changes to occur. Some potentially beneficial mutations that would have died with a person who was otherwise unfit will be saved and spread in the population. Then, when the population crashes (as it inevitably will? I don't know) those mutations which otherwise would have disappeared are available. It's really the same way that evolution operates in other circumstances--good times, bad times, the changes are what cause things to happen. Actually, the rapid speeding up of evolution that this paper suggests is itself already proving that. The development of agriculture caused a lot of adverse physical changes in people--the average height dropped 6 inches, the development of the chronic diseases of civilization (diabetes, tooth decay, osteoporosis, cancer, etc. which are unknown in wild animals and prehistoric humans) but, it also allowed the population to explode exponentially. Now we see that there was a simultaneous rapid increase in evolution as well. Modern medicine may only compound that. I think we are reaching the upper limits of population for that experiment, however.

[Idolfan]

I did not understand the quote at all but I find the subject very interesting, thanks for the links. I had thought that natural selection had died thanks to medicine and the weak's control over the strong. But I'll see what these can convince me into thinking! Remember that in this egaliterianist society the weak are allowed to live, so the most retarted features in people are not going to stop them from reproducing.

[Super Duck]

Wow. I have high interest in becoming a genetic scientist and this is really intriguing. I think Scatterbrain is right. Soon enough we will be able to say "Thanks; but no thanks" to Mother Nature and scrap natural selection, using genetic engineering to advance our anatomy's capabilities to unimaginable levels. I would be in no way surprised if I visited the year 3000 to find that humans had wings, gills and tails. Lol! OK, just searched Google. Looks like I was wrong ... but have a gander and see what you think of your children's children's children:

[tkdyo]

loool superduck, I highly doubt we will end up that way. but genetic engineering is a very real possibility soon, if not even for little things like hair color and atletic potential

[Taosaur]

I saw a press article on this study, and to me it makes more sense than the 'we broke evolution' argument. The latter relies on a simplistic, deliberate view of past evolution and a narrow view of fitness--i.e. a species changes gradually and uniformly in one direction, and what's fit for a tiger is also fit for a man. In fact, any broadly distributed genus or species, I would think, will show tremendous diversity and not appear to be 'evolving into' anything. If they're also impacting their environment, and especially if they're selecting for innovation, they're actually putting stronger selective pressure on themselves and everything else in their environment. That pressure will only manifest as diversity within the species unless a population becomes completely isolated for a very long time. For human evolution to lead to speciation, we'll need to either leave this planet or render it much less hospitable to ourselves, thereby limiting our capacity to travel and communicate.

[Moonbeam]

I saw a press article on this study, and to me it makes more sense than the 'we broke evolution' argument. That was the interesting thing about it; people are always assuming "evolution" is over, but instead we see that genetic change has speeded up (if this turns out to be the case--it's just one article; I've seen some things being written against it already but haven' read them yet.) I thought another interesting thing was how instead of blending, like we are "supposed" to be doing, there is actually seperation of peopole on the different continents genetically. Not that that really means anything to humans for a long, long time--much longer than any of us have to worry about. It was just interesting that it shows that something everyone assumed to be the case may be wrong. Superduck--unless our ideas about beauty evolve pretty quickly too, I can't see us changing into that! Sexual selection is a huge factor in evolution. I can understand the eyes and nose (protection from pollution), and the big finger (all the better to type with), but what's up with the enormous testicles, anyway? Big testicles in males correlate with female promiscuity, but if all the guys look like that, I don't think that's going to happen.

[ninja9578]

Wow, that seems counterintuitive. Evolution is based on survival of the fittest, modern medicine no longer makes that true. People born with severe handicaps are living and breeding, when (harsh as it sounds) 100 years ago they wouldn't have.

[The Cusp]

I don't like the sound of that at all. If we're adapting to our environment faster, that means as a species we're becoming more specialized. Historically, species that are overly specialized are the ones that become extinct.

[Spartiate]

I don't like the sound of that at all. If we're adapting to our environment faster, that means as a species we're becoming more specialized. Historically, species that are overly specialized are the ones that become extinct. But we aren't specialized to just one environment, humans are spread out all over the globe. Some of us have adapted to the cold, others to the heat, some to the desert, others to the rainforest, etc.

[Taosaur]

Wow, that seems counterintuitive. Evolution is based on survival of the fittest, modern medicine no longer makes that true. People born with severe handicaps are living and breeding, when (harsh as it sounds) 100 years ago they wouldn't have. Again, you're thinking too narrowly about "the fittest." We don't live in a jungle and don't need to be fit for one. Instead, we live in diverse and rapidly changing environments, and we're actively selecting for individuals with the capacity to change that environment more. Think about it--when has any species lived in an environment that changed so much for so long? It makes sense that selection pressure would be increased, and the rate of change thus increased as well. Moonbeam, I'm going back into the article before I really respond, but I have some ideas on racial divergence--I would expect increased diversification, with many present ethnicities persisting largely as-is, but also new ones emerging at a greater rate, and more multi-racial/raceless individuals: more a diversification than a blending. We'll likely see some ethnicities emerge independent of geography altogether--global nomads. Unless, of course, we're unable to solve energy issues and have to ground a lot of planes...

[Moonbeam]

Moonbeam, I'm going back into the article before I really respond, but I have some ideas on racial divergence--I would expect increased diversification, with many present ethnicities persisting largely as-is, but also new ones emerging at a greater rate, and more multi-racial/raceless individuals: more a diversification than a blending. We'll likely see some ethnicities emerge independent of geography altogether--global nomads. Yes, I guess increased divergence doesn't mean that there can't be more multi-racial people at the same time, so that makes sense.

[Mystic7]

Some recent changes: the ability to digest milk I think your getting a bit desperate here....

[The Cusp]

I think your getting a bit desperate here.... When she's right, she's right. The prevalence of lactose intolerance in adults of certain ethnic groups African Blacks95% Indians90% Asians90% North American Blacks75% Mexican Americans75% Mediterraneans60% North American Whites15% And an article on the subject: http://www.news.cornell.edu/stories/...rding.ssl.html

[Mystic7]

The point is we have drunk milk for a long time who cares. Evolution is not just about the ability to digest milk, or have blue eyes. people are much different than they were 40,000 years ago, or even 1000 or 2000 years ago Yes, there's less people flying on broomsticks and a hell of a lot more consumers.

[Taosaur]

I thought another interesting thing was how instead of blending, like we are "supposed" to be doing, there is actually seperation of peopole on the different continents genetically. Okay, having read the whole article (which required a crash course on terminology in genetics and evolution, thank you internets ), I think you're inferring too much from the data. Their ability to pick up new positive adaptations with their methodology trails off as you approach the present, so it doesn't say much about the impact of the past millennium's fast, long-distance migrations. The fact that populations on different continents showed mostly different adaptive changes is consistent with the divergence that leads to "races" in the first place. It would be great to get a detailed look at, say, the last hundred years vs. the last thousand, but I don't think the statistical method and adequate data set exist yet.

[Taosaur]

The point is we have drunk milk for a long time who cares. Evolution is not just about the ability to digest milk, or have blue eyes. Well, yes, in the purview of this article and this thread, it is. No one's talking about speciation or early hominids here, so you can crawl back under the bridge.

[R.D.735]

The greatest changes have probably occurred in our brains. Since they rely so much upon the environment to develop certain structures, it's likely that modern humans' brains have adapted in much more extreme ways than other parts of our biology. Of course, it's impossible to see the brain structure of anyone that lived so long ago, but it could be possible to extrapolate from primitive tribes of modern humans that still exist.

[Mystic7]

The greatest changes have probably occurred in our brains If the greatest changes have accurred in our brains. Why can we still not look after our planet? Tell me what part of the brain have we damaged Mr Spock.

[The Cusp]

But we aren't specialized to just one environment, humans are spread out all over the globe. Some of us have adapted to the cold, others to the heat, some to the desert, others to the rainforest, etc. That's all fine and dandy if the climate stays the same, but if it should drastically change? Heck, what would become of us if we simply lost electricity for some reason?