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    •  
      CommentAuthorbadger
    • CommentTimeDec 10th 2007 edited
     (260.1)
    John Hawks will be fleshing this out over the next few days, but this is his first post on the paper. There's also an article on PhysOrg.com with the addition of "Findings suggest we are becoming more different, not alike" (and they accidentally broke the embargo last week, but yanked the story before i could read it.) I'm kinda giddy at the sheer weirdness of it.

    Study co-author Gregory M. Cochran says: “History looks more and more like a science fiction novel in which mutants repeatedly arose and displaced normal humans – sometimes quietly, by surviving starvation and disease better, sometimes as a conquering horde. And we are those mutants.”


    Just found a thread on Metafilter (yeah, obvious,) from which i'm lifting the link to this blog post critiquing the paper.
  1.  (260.2)
    Good stuff badger, thanks. Interesting conclusion from your second link:
    It is sometimes claimed that the pace of human evolution should have slowed as cultural adaptation supplanted genetic adaptation. The high empirical number of recent adaptive variants would seem sufficient to refute this claim.
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      CommentAuthorScribe
    • CommentTimeDec 10th 2007
     (260.3)
    I am curious if this is based off of evolution, or man tampering with design via medicine.
    • CommentAuthorKosmopolit
    • CommentTimeDec 10th 2007
     (260.4)
    Basically, Scribe, our environment includes other people and social institutions as well as technology and the physical environment.

    Our social environment keeps getting more complex and, critically, more diverse. The skills you need to survive in a Brazilian favela are different to those you need to survive as a peasant farmer in Vietnam and those in turn are just as different to the skills you need to survive and maximise your reproductive success in a developed western society.

    So, for example, there's a gene variant (I forget the name) that seems to have originated in the last 20,000 years or so - which is very recent in evolutionary terms - it's in one of the key genes controlling language skills and seems to affect brain development. Exactly what it does we aren't certain yet but it seems like people with the new variant are better at verbal communication. Something like 70% of the world's current population has that variant now.

    So its environment not technology, so far. The changes that'll come once genetic engineering really gets going are going to be orders of magnitudes greater.

    If not for the legal and ethical barriers we could probably create a superhuman now. We've already identified single-point mutations linked to greater intelligence, greater physical strength, a superior immune system and longer life expectancy. (Of course, when I say superhuman I'm talking Doc Savage not Superman.)
    •  
      CommentAuthorUnsub
    • CommentTimeDec 10th 2007
     (260.5)
    I'm having a time out until I can learn some manners.
    Maybe the skills needed are different but the genetic characteristics are the same. Being a big strong intelligent alpha male with symetrical features and oozing self confidence will make you a winner everywhere.
    • CommentAuthorKosmopolit
    • CommentTimeDec 11th 2007 edited
     (260.6)
    "Being a big strong intelligent alpha male with symetrical features and oozing self confidence will make you a winner everywhere."

    Not if, for example, you're a Dalit in parts of India, where they'll probably make you dead.

    Also ever hear of the sneaky fucker" strategy in various animal species? That's where while the alpha males are beating the crap out of each other, smaller males sneak in and impregnate their females.

    Come to think of it, the optimal reproductive strategy for a male in most western societies is probably to become a sperm donor which gives you up to about eight kids for a minimal investment of time and resources.
  2.  (260.7)
    PhysOrg.com is my favourite site.

    Cheers,

    Chris.
    •  
      CommentAuthorbadger
    • CommentTimeDec 11th 2007
     (260.8)
    From the Gene Expression blog:
    But there is another angle too: exogenous or extrinsic factors, natural selection as we conventionally understand it. These exterior parameters frame the selection coefficients which drive mutations toward extinction or sweep them up to fixation. And, importantly, some of these parameters are strongly shaped by population size as well. Consider disease, which is likely strongly subject to density and interconnectedness. A world with more humans is a world with more hosts, and remember that many of the arguments for increased rates of substitution derive from pathogen models whose effective population size is contingent upon warm bodies available to infect!

    exposure to viruses and bacteria could cause humanity to speciate. It's not just about culture.

    He also points to an older post of his, that links to some papers from the past few years on recent human evolution that are relevant to the new paper.
    • CommentAuthorKosmopolit
    • CommentTimeDec 11th 2007
     (260.9)
    "Exposure to viruses and bacteria could cause humanity to speciate."

    Everywhere except Africa humans are an invasive species (AKA an introduced pest). That's why there are so many more pathogens and parasites that target humans in Africa.

    We haven't been around most other places long enough for the local disease-causing beasties to get properly accustomed to us.
  3.  (260.10)
    "We haven't been around most other places long enough for the local disease-causing beasties to get properly accustomed to us."

    That's not all. Our rapid global travelling allows far more viral/gene modifying diseases to spread far further and mutate in greater varieties than before. We're hit by more virii than before but we also develop better immunities so there's less in the way of Typhoid Mary brutality and just gentler waves of sniffles every three to five weeks.

    Cheers,

    Chris.
  4.  (260.11)
    I'm having a time out until I can learn some manners.
    I got a discover magazine somewhere, in it is a short article about how they moved some type of Chiclad (a fish) from salt water to freshwater and in just a few generations it lost a fin and gained a bone.

    Evolution is inconceivable as we don't really have any 100% accurate information on peoples more than a couple hundred years ago. so who knows what other little changes could have been made. It'll be interesting to see what info(pics, videos, etc) of people from today survives in half a century, and how that compares to the people then. Has anyone ever compared the DNA of a mummy to someone from today?

    I saw another program of the Discory Channel, and they said it takes approximately 2,000 years to go from black to white(Assuming you stay in the right environments/etc). Evolution may happen faster than we think. I know a number of "full blooded african-americans" who are pretty pale.
    • CommentAuthorFlabyo
    • CommentTimeDec 11th 2007
     (260.12)
    You could argue that technology is part of the environment as far as human evolution is concerned. Pretty much as soon as we started using tools we were in a position where our technology advantage gave us as much of an evolutionary edge as the biological improvements that had given us the brainpower to think of creating them in the first place. It's not a huge leap from there to assume that the prescence of particular technologies in a society would affect how that species evolves relative to one without.
  5.  (260.13)
    There are other examples of animal evolution directly affected by human intervention - such as American Rattlesnakes mostly losing their rattle due to attrition at the hands of jumpy cowboys.

    As for us - as a layman I'm not certain, but I have heard discussion that there seems to be great adaptability in the genome - partly through the action of transcriptase RNA, partly (according to new research, which of course I can't bloody find right now) that the introns (I never use the term 'junk DNA') may be adaptive and influential. It's stuff like this that makes me snort at hard-liner Darwinians like Dawkins - not only do neo-Lamarckian models fit a lot of the data better, but we even have models for their action.
    • CommentAuthorKosmopolit
    • CommentTimeDec 11th 2007
     (260.14)
    Cat, I take it you're familiar with the "famine baby" phenomena>

    Dutch women who gave birth during the winter of 1944 (known as the famine winter in Holland) had smaller than average babies. That's no surprise - but those babies grew up to have kids of their own, who were also smaller than average. I think there's some evidence for the effect in the next generation as well.

    It seems to be passed down only on the female side and it appears to be an epigenetic effect - that is the maternal starvation didn't alter the daughters' genes, it altered how those genes are expressed.

    You also get heat-shock proteins (HSPs), HSPs are produced in response to thermal stress but also to extended hunger and other stressors. They help the cells to cope by speeding up the break-down of chemicals the cells no longer need and their re0use. They also alter methylation, the process which helps determine which genes are expressed (i.e. translated into RNA and made into proteins). The alterations are random but the net effect is to increase the rate of change in expression when cells divide.

    So if your body is under prolonged stress, it effectively increases the rate of cellular mutation (not sure if that's the right technical term to use here) to try and find solutions to the increased stress. If the cells involved are germ lines, the changes are transmitted to the offspring.

    I think I read somewhere that the changes are to some extent predictable and reversible. Expose mice to prolonged heat and they 'll produce offspring with adaptations like thinner hair and an increased panting reflex. Take the offspring and expose them to cold and inside a couple of generations the adaptations disappear.
  6.  (260.15)
    Dutch women who gave birth during the winter of 1944 (known as the famine winter in Holland) had smaller than average babies. That's no surprise - but those babies grew up to have kids of their own, who were also smaller than average. I think there's some evidence for the effect in the next generation as well.


    And to think we used to laugh at Lamark...
    • CommentAuthorHarvey
    • CommentTimeDec 12th 2007 edited
     (260.16)
    @ Kosmopolit

    I'm not sure babies born after the famine winter of 1944 are the greatest example of adaption - the certaintly had a low birthweight, but they had a stack of other problems too, like cardiovascular disease, diabetes and greater rates of adult obesity (if I remember right) - it wasn't that they were adapted to be smaller in times of no food, just that they were sick.

    I also wasn't aware of a role in methylation for HSP's - I always thought that was the exclusive preserve of the DNA methyltransferase enzymes. If you have a source I'd be interested to take a look at it
    • CommentAuthorKosmopolit
    • CommentTimeDec 12th 2007 edited
     (260.17)
    Hi Harvey,

    Please bear in mind that I'm a layman who gets most of his science from New Scientist.

    I looked for peer-reviewed articles on the subject and this is one of the first I found. i'm afraid I only have access to the abstract:

    http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WSR-417MP80-F&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0765e980180ac4b0fe4df0e9670e3c49

    Structural, biochemical, and genetic techniques were applied to investigate the function of FtsJ, a recently identified heat shock protein. FtsJ is well conserved, from bacteria to humans. The 1.5 Å crystal structure of FtsJ in complex with its cofactor S-adenosylmethionine revealed that FtsJ has a methyltransferase fold. The molecular surface of FtsJ exposes a putative nucleic acid binding groove composed of highly conserved, positively charged residues. Substrate analysis showed that FtsJ methylates 23S rRNA within 50S ribosomal subunits in vitro and in vivo. Null mutations in ftsJ show a dramatically altered ribosome profile, a severe growth disadvantage, and a temperature-sensitive phenotype. Our results reveal an unexpected link between the heat shock response and RNA metabolism.


    Beyond the Chaperone/Protease Paradigm

    The majority of heat shock proteins characterized function either as molecular chaperones or as proteases ([16]). However, the recent discovery and functional analysis of several E. coli heat shock proteins has revealed functions that significantly alter this paradigm. We have shown that FtsJ, a well-conserved heat shock protein, is structurally related to methyltransferases and is involved in 23S rRNA methylation in the cell. We have previously described another RNA binding heat shock protein, Hsp15, that binds with high affinity to 50S ribosomal subunits ([27]). Hsp15's crystal structure revealed that it comprises a novel RNA binding motif shared by over 500 sequenced proteins including ribosomal protein S4 and some tRNA synthetases ( [38]). Functional analysis suggested that Hsp15 is involved in recycling 50S ribosomal subunits that are blocked by nascent chains. An additional protein involved in RNA metabolism, the tRNA dimethylallyl diphosphate transferase MiaA, is under heat shock regulation ( [40]). The described functions of all of these novel heat shock proteins suggest that protein damage control is clearly not the sole role of the heat shock proteins in the cell. Our results show that RNA-related functions are also important in the heat shock response.



    The key point regarding the hunger babies is that they transmitted their smaller stature to their own children. I'm sure there was a simple malnutrition factor involved but I understood that by the time they reached adulthood their overall health wasn't significantly worse than their peers. From what you're telling me that's incorrect.
    • CommentAuthorHarvey
    • CommentTimeDec 12th 2007
     (260.18)
    @ Kosmopolit

    I came across the famine baby idea as a study on the effects of malnutrition in the mother on children, and I'm fairly sure there was a stack of problems with them - I'm fairly sure their study is oneline somewhere.

    The HSP protein work is interesting - I think that particular protein is found in bacteria, but it doesn't invalidate your original point, of course, that environmental effects can affect the expression of DNA. I'd personally be inclined to be slightly sceptical of how much this can affect the genotype (ie the actual DNA code passed down through the line), but in the absence of any concrete data (confirming or not )those points, it's going to remain just an opinion