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Study Detects Recent Instance of Human Evolution 503

Posted by Zonk
from the genetic-not-mental dept.
The New York Times is running a Sunday article regarding new evidence about 'recent' human evolution. A research team at the University of Maryland has done some work looking at the rise of lactose tolerance in the human populations of Africa. From the article: "The principal mutation, found among Nilo-Saharan-speaking ethnic groups of Kenya and Tanzania, arose 2,700 to 6,800 years ago, according to genetic estimates, Dr. Tishkoff's group is to report in the journal Nature Genetics on Monday. This fits well with archaeological evidence suggesting that pastoral peoples from the north reached northern Kenya about 4,500 years ago and southern Kenya and Tanzania 3,300 years ago ... Genetic evidence shows that the mutations conferred an enormous selective advantage on their owners, enabling them to leave almost 10 times as many descendants as people without them. The mutations have created 'one of the strongest genetic signatures of natural selection yet reported in humans,' the researchers write. "
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Study Detects Recent Instance of Human Evolution

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  • by Elminst (53259) on Monday December 11, 2006 @07:14AM (#17192600) Homepage
    Nah.... too easy.
  • Micro vs Macro (Score:4, Insightful)

    by JPriest (547211) on Monday December 11, 2006 @07:27AM (#17192656) Homepage
    Even most Creationists conform to at least some kind of evolution (micro).


    For example, if Adam & Eve were the only parents why are people so different?

    How did all the animals fit on Noah's Ark? If there were just 2 of the animals (dogs for instance) why are they so different now?

    What about humans on the Ark, were they forced to inbreed for a second time to populate?

    Also, we may not have the ability to actually observe Macro Evolution, but Micro Evolution has been evident for some time now. We have documented proof that Americans have gotten taller for instance.

    So when you have small changes over a small period of time, is believing that over a large period of time you could have large changes really that unreasonable?

    • Re: (Score:3, Informative)

      by Sirch (82595)

      We have documented proof that Americans have gotten taller for instance.
      I believe (no sources) that that is most likely down to better nutrition (in the US? Hah! etc), rather than evolution.
    • Re:Micro vs Macro (Score:5, Informative)

      by solanum (80810) on Monday December 11, 2006 @07:48AM (#17192750)
      It's not actually that simple. For example, the increase in height in Westerners isn't micro-evolution it's simply diet. When man went from hunter-gather (the state to which we evolved), to an agrarian lifestyle, the quality of diet went down, it hit rock bottom in Europe in the middle ages where teh majority of the population were quite severly malnourished and therefore short. The heights we are currently reaching (pun intended) are basically those of our hunter-gatherer forefathers, because as a population the quality of our diet over the last 50 years has improved so much. Of course we're probably heading down the path of too much now...

      So my point is, that it's not easy to define or prove 'micro-evolution'. Just to clarify, I am a biologist by trade and am quite comfortable with the punctuated-equilibrium model of evolution, I'm certainly not arguing that evolution doesn't happen, just that we have to be careful with our conclusions.
    • by ozbird (127571) on Monday December 11, 2006 @09:13AM (#17193236)
      According to "The Restaurant at the End of the Universe", Noah was the captain of the B-Ark, which contained the TV salesmen, hairdressers, creationists; plus the DNA samples of each of the animals (to fit them all in the limited cubic-cubits available.) Unfortunately, before the C-Ark (containing the refrigeration mechanics etc.) arrived, the samples had begun to thaw; the scientists (on the A-Ark) did their best, but many mutations had occurred - leading to such monstrosities as the poodle and chiahuaia.
    • Re: (Score:3, Insightful)

      by iknowcss (937215)
      Considering God was supposed to have created the perfect system for his perfect creation (Humanity), wouldn't it make most sense for the system to adapt and evolve? It makes sense in other situations. Imagine the perfect computer system. Wouldn't it make most sense for it to be dynamic, able to allocate resources (CPU, bandwidth, etc) in places where they are most heavily requested?

      Eh, just a passing thought I have from time to time. I haven't had a chance to state it as eloquently as I'd like, but the gis
    • by cyberscan (676092) * on Monday December 11, 2006 @10:34AM (#17193952) Homepage
      "For example, if Adam & Eve were the only parents why are people so different?"

      I believe that they were not the only parents. It looks like to me that the creation events of the first chapter of Genesis are a separate event from the creation spoken out in the second chapter. If, as I believe, this is true, it would very well explained how Cain could have met his wife.
      The humans from the first chapters of Genisis were the hunter-gatherers while the creation of the man in the second chapter was hte beginning of agriculture.

      "How did all the animals fit on Noah's Ark? If there were just 2 of the animals (dogs for instance) why are they so different now?"
      The actual Hebrew word that is translated to Earth is eretz. Eretz means land or soil. Was it the entire planet that was flooded, or was it the entire land (in that area)? Many cultures totally unrelated to Judeaism and Christianity have records of the Flood. It is obvious that the Flood was a major world event, and to me it looks like the flood covered the entire land (in that area).

      "What about humans on the Ark, were they forced to inbreed for a second time to populate?"
      Maybe.

      "Also, we may not have the ability to actually observe Macro Evolution, but Micro Evolution has been evident for some time now. We have documented proof that Americans have gotten taller for instance."
      Americans have gotten taller, and when conditions are right, Americans can become shorter as well. Evolution, natural selection, or whatever you want to call it is a mechanical process, nothing more. There are switches with this program that allow certain features to be turned on and off as conditions warrrant. Software crackers also manipulate these switches to affect the behaviour of a program (by switching of registration screens, etc). Computer scientists are in some cases designing programs so that these types of switches can be easily activated and deactivated by other processes in order to try to cause programs to self improve.

      The point is that I have seen physical evidence, historical evidence, and linguistic evidence, and archealogical evidence of Biblical truth as well as fossil evidence of the mechanical process of evolution. Much of both evidence goes against what many mainstream Christian BELIEVE, but it does not go against what the original (Biblical) scriptures ACTUALLY SAY. Am I a Christian? no, I am not. I am a Messianic Jew. I also resent the anti-creator bias that is displayed in slashdot as well as many (not all) scientific circles.

      Just as there is physucal evidence of the mechanical process of evolution, there is also physical evidence of Biblical authenticity.
      Look at http://www.bibleplus.org/discoveries/sodomfound.ht m [bibleplus.org]
      Long before scientists stated (and proved) that the heavens are expanding, the Bible has stated this fact (Job 9:8, Isaiah 40:22, 42:5, as well as many others). I could go on and on about many pieces of evidence, however this evidence is not really hidden. One can find references to most of it online. Yes, I fully expect that this post will be modded down and labelled as flaim bait (typical). However I post such information so that people will get to see a broader view and diverse opinions.
      • by elrous0 (869638) * on Monday December 11, 2006 @10:57AM (#17194226)
        The point is that I have seen physical evidence, historical evidence, and linguistic evidence, and archealogical evidence of Biblical truth

        Speaking as a former historian, I can tell you that history and faith do not mix well--and shouldn't. You can not use history and science to "prove" supernatural assertions (if you could, they wouldn't be supernatural).

        Yes, the Bible includes much important historical information that historians use (and argue about). But using historical and archaeological sources to argue that the Bible is accurate in many of its historical assertions does absolutely nothing to support or renounce its supernatural claims. Historians have, for instance, long accepted that Jesus was a real historical figure. But that acknowledgement can offer nothing to the argument over whether or not he performed miracles, or was the "Son of God."

        -Eric

      • by Wylfing (144940) <brian AT wylfing DOT net> on Monday December 11, 2006 @12:36PM (#17195760) Homepage Journal

        Many cultures totally unrelated to Judeaism and Christianity have records of the Flood.

        There are some word games being played here. First, "many" cultures is quite a stretch. There are some half-dozen cataclysm stories that parallel the flood story told in Genesis.

        Second, calling these other stories "unrelated" is false. Greek and Sumerian cultures were "unrelated" to Hebrew culture? I think not. A large weight of evidence suggests the opposite of what you assert. These ancient civilizations were quite mobile and it is highly likely that these "unrelated" flood stories have a common root, which was passed among these people by oral storytelling tradition, through which it became localized.

        Third, these stories are not "records" any more than the story of Paul Bunyan [wikipedia.org] is a "record" of how the Grand Canyon was formed. Now, I am not arguing whether the story has a basis in fact; believe about that what you will. I am only saying that it does not qualify as a historical record.

        I also resent the anti-creator bias that is displayed in slashdot as well as many (not all) scientific circles.

        I submit that what you perceive as "anti-creator bias" is instead an aversion to black box thinking. If you see the work of God in the emergence of life on Earth, more power to you. However, we cannot postulate that the emergence of life is caused by a creator, because we then fall off the map of science. All the mechanics become hidden away inside a magical black box where we cannot see them. And since we cannot make observations, there is no way to prove any of the claims wrong. Ergo, science is impossible.

        There is no bias present, only a desire to do proper science.

  • So I read the article and it sounded like there was never a time they could point to and say 'here's when the mutation occured'. Instead they stated when the mutation started to have an effect on the population by weeding out those without the mutation.

    So I'd say natural selection happened as recently as ~5000 years ago, not evolution. But maybe TFA didn't explain everything.
    • by arun_s (877518) on Monday December 11, 2006 @08:07AM (#17192822) Homepage Journal
      So I read the article and it sounded like there was never a time they could point to and say 'here's when the mutation occured'.
      It doesn't usually work that way. Evolution is a continuous process, like, for instance, hair growth. Consider a random population of 1000 short haired people. At what instance does the average length cross 3 cm? There really isn't a distinct time when it happens, since several may visit the barber on different days, making the average shuffle up and down (although maintaining a noticeable upward trend all the way). You could only conclude that, after say, 2 months, the average length in that sample was comfortably over 3 cm, although there might not necessarily have been a single instant when the change occured.
      Alright that wasn't a very good analogy, but I hope you get the point: In evolution, the average trends in the gene pool are what are considered rather than a specific instance of change. (IANAEB (I'm not an evolutionary biologist), so please correct me if I'm wrong)
    • by Sique (173459)
      Normally the acutal mutations has happened some generations earlier than the first occurence in the phenotype. Most mutations are regressive, that means they are overridden by a dominant allel (gen variant) on the other chromosome (chromosomes other than the X or Y have a twin in the genome). This gives the mutation the chance to be spread in the population without having an actual effect on it. Only if two people carrying the mutations meet and have children together, there is a 25% chance that the mutatio
    • by masklinn (823351)

      Natural selection is one of the evolutionary processes, just as mutations are.

      Natural selection is part of evolution, not something completely different and disjoint.

  • by $RANDOMLUSER (804576) on Monday December 11, 2006 @07:35AM (#17192686)
    I realize that this is popular press and all, but why is mutation always mentioned, but crossover [wikipedia.org], never so?
    Generally speaking, mutation is almost always fatal, crossover is almost never so. Crossover keeps you "in the genome", where mutation is just as likely to kick you out of it. My own theory is that mutation is the driver behind speciation, while crossover is the driver behind evolution.
    I've run lots of GAs with mutation turned off, letting crossover [wikipedia.org] do all the work. Crossover, not mutation, is what lets a population do that slow walk/hillclimb, over time, through the genetic landscape.
    • by Rakishi (759894)
      Crossovers don't usually create anything "new" but simply mix up existing traits and information. So while crossovers introduce variance into the population and help new genes spread their influence is limited. At best they'll give you a good set of genes but you're still limited to what you started with. Mutations on the other hand introduce new genes which may (or may not) have a beneficial effect.
    • by BerntB (584621)

      I've run lots of GAs with mutation turned off, letting crossover do all the work.

      Then you do crossover so one in the new generation can get "extra" material from a parent? In that way, a gene can be copied and modified. That is a known mechanism in the genome. There are lots of genes in every species that are modified copies of other genes.

      Without any new species being created.

      You could probably do a trivial mathematical argument that such a crossover operation in the normal genome has the same

    • by kshort (1017266) on Monday December 11, 2006 @08:08AM (#17192824) Homepage
      I'm a geneticist, and we typically use the terminology 'mutation' to describe any change in DNA which escapes the cell's natural ability to inhibit external of internal modification of the genome, typically using 'proofreading' mechanisms, or all the way through to cellular apoptosis to delete entire cells with certain (what the cell thinks are) detrimental mutations. Such simple changes, if they escape correction or deletion, most definitely have the ability to cause major problems, but on the flip side those mutations have the ability to modify the activities of proteins which can be advantageous (and others may do nothing at all). Whilst examples of advantageous mutations are few and far between on timescales that we can appreciate in concordance with a human lifetime, in the evolution of a species such mutations are seen to occur rather rapidly. Crossover is never a term I have come across in the definition of these terms, unless you're talking about recombination, which is another thing entirely.
    • Re: (Score:3, Interesting)

      by Vreejack (68778)
      Most mutations are not fatal, they are neutral, having no observable effects in the offspring. Elsewise, you would probably be dead. It is these random mutations that build up the gene pool, giving natural selection something to work on, and without which crossover would have no effect.

      Actually, strong selection pressures are identified on a gene by the absence of crossover. When a gene is strongly selected the other genes and junk near it tend to be carried along intact, instead of being carved up by re
    • Re: (Score:3, Interesting)

      by cnettel (836611)
      Actually, major crossover events, creating a different chromosomal makeup, can be a very efficient barrier against fertile off-spring. We can observe lots of single nucleotide polymorphisms (SNPs), the "purest" mutation you can achieve, in humans. Some of them cause known phenotypical differences, far from all of them lethal. Then, we also have all those mutations that really just replace one codon for an amino-acid with another one for the same residue, with very limited effects, if any.
    • Because it's a SNP [wikipedia.org] (i.e. a point mutation) and not recombination.
    • by Guillermito2 (911866) on Monday December 11, 2006 @09:02AM (#17193160) Homepage

      why is mutation always mentioned, but crossover, never so?

      You're right. Point mutations (like a bit flipping in geekspeak) are only one kind of evolution mechanism, although it can be caused by several mechanisms (error during copy of the genome, which in fact happens all the time, 1 or 2 per billion base pair per duplication if I remember, a rate that would never be tolerated in computers, it's like 1 bit flipping every 125 Mb, also chemicals, cosmic rays, etc). But to participate in evolution, it has to be transmitted to the germline. So the mutation has to happen in your balls, in other terms.

      Generally speaking, mutation is almost always fatal

      In fact, no. There are many point mutations between human beings, they are called SNPs (Single Nucleotide Polymorphism) and there is a big worldwide project that mapped many of them them. Most of them are silent, or at least do not have a black and white effect (but it sometimes unfortunately happens : one single mutation in 3 billions nucleotides and you will suffer a painful and slow death). Remember that people used to say that most of the human genome is junk (this junk actually seems to be more and more important, but it's mainly "apart from defined genes - a few percent - we have no idea what the rest is doing here").

      A point mutation in a primate genome would be like flipping a random bit in an overbloated Visual Basic application. It's very likely the program will still be funtional. As opposed to changing a random bit in a very size optimized assembler program, which is almost certainly going to crash.

      My own theory is that mutation is the driver behind speciation, while crossover is the driver behind evolution.

      I'm not sure it's supported by facts, although it's an interesting theory. Don't forget that there are even other ways to modify a genome. An important one is polyploidy : suddenly for some reason an organism doubles the number of chromosomes (a cell that duplicate the genome but fails to separate into two daughter cells). As you suddenly have twice the number of redundant genes, then the new genome is like a playground for other kinds of mutation, as time and random can play around with the copies of the genes without much effect, as long as there is one functional copy.

      Another mechanism, as opposed to point mutation or whole genome doubling, is deletions or copies (in tandem, or inverted, or somewhere else, or in the middle of another gene) of huge portions of the genome (several thousands of nucleotides). In fact, there was a paper in Nature two or three weeks ago that compared the chimp and the human genome for this type of big chunk mutation.

      A last one is through the action of transposons which may be some old retrovirus succesfully inserted in the genome. For some reason, sometimes a transposon get excited, wakes up and it will excise itself from its current location and jump somewhere else in the genome. But this process is never perfect, and the jump removes or leaves a few nucleotides that are going to induce a mess if it's inside a gene.

      There are others ways to fuel evolution at the genome level, but that were the ones that came on top of my head quickly. Plus I need a coffee.

      • Re: (Score:3, Funny)

        by gowen (141411)
        Tell your facts to shut up.
        They cannot compete with the sheer truthiness of revealed insight.
  • Didn't we see human evolution pretty close to home? But only backwards;) [bushorchimp.com].
  • All I can find is their list of publications [umd.edu] and their 'Homeland Security' website [umd.edu]. Apparently UM is very 'prepares' - or they've just made a bunch of lists with staff people's names on them.
  • Study Detects Recent Instance of Human Evolution
    Oh, genetically. Yes, ok, right. Apart from that we're still as stupid as we used to be. Yay.
  • Convergent adaptation of human lactase persistence in Africa and Europe


    A SNP in the gene encoding lactase (LCT) (C/T-13910) is associated with the ability to digest milk as adults (lactase persistence) in Europeans, but the genetic basis of lactase persistence in Africans was previously unknown. We conducted a genotype-phenotype association study in 470 Tanzanians, Kenyans and Sudanese and identified three SNPs (G/C-14010, T/G-13915 and C/G-13907) that are associated with lactase persistence and that have d
  • by Jugalator (259273) on Monday December 11, 2006 @08:44AM (#17193032) Journal
    - About only 2% of Swedes are lactose intolerant.
    - About 20-60% of Africans are lactose intolerant.

    I can personally see a much stronger signature of these genetic traits in Scandinavia? Is the difference that this evolution was not "recent"? Because surely it has to be some form of natural selection causing this in Scandinavia too, perhaps trigged earlier for some reason?

    Some useful links:
    - Lactose intolerance by human groups [wikipedia.org].
    - World map with lactose intolerance distribution [wikimedia.org].
  • I think we should be clear here, what they are discussing is natural variation within a single species, not an evolution from one species to another.
  • Obligatory (Score:4, Funny)

    by inviolet (797804) <slashdot@ideasmatt e r .org> on Monday December 11, 2006 @09:19AM (#17193266) Journal

    In Soviet Russia, lactose evolves tolerance for YOU!

  • Shens! (Score:3, Informative)

    by Bryansix (761547) on Monday December 11, 2006 @12:35PM (#17195738) Homepage
    There was an article in the LA Time Magazine called West [latimes.com] that talked about Raw Milk. That is it talked about milk that was not pasteurized. It mentions that there are enzymes naturally occurring in milk that allow people to digest milk. That means that the ability to tolerate Lactose is not a very big deal since people thousands of years ago presumably were not pasteurizing milk.

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