[Paleopsych] New Scientist: Civilisation has left its mark on our genes

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Civilisation has left its mark on our genes
http://www.newscientist.com/article.ns?id=dn8483&print=true

      * 22:00 19 December 2005
      * Bob Holmes

    Darwins fingerprints can be found all over the human genome. A detailed look 
at
    human DNA has shown that a significant percentage of our genes have been 
shaped
    by natural selection in the past 50,000 years, probably in response to 
aspects of
    modern human culture such as the emergence of agriculture and the shift 
towards
    living in densely populated settlements.

    One way to look for genes that have recently been changed by natural 
selection is
    to study mutations called single-nucleotide polymorphisms (SNPs) 
single-letter
    differences in the genetic code. The trick is to look for pairs of SNPs that
    occur together more often than would be expected from the chance genetic
    reshuffling that inevitably happens down the generations.

    Such correlations are known as linkage disequilibrium, and can occur when 
natural
    selection favours a particular variant of a gene, causing the SNPs nearby to 
be
    selected as well.

    Robert Moyzis and his colleagues at the University of California, Irvine, 
US,
    searched for instances of linkage disequilibrium in a collection of 1.6 
million
    SNPs scattered across all the human chromosomes. They then looked carefully 
at
    the instances they found to distinguish the consequences of natural 
selection
    from other phenomena, such as random inversions of chunks of DNA, which can
    disrupt normal genetic reshuffling.

    This analysis suggested that around 1800 genes, or roughly 7% of the total 
in the
    human genome, have changed under the influence of natural selection within 
the
    past 50,000 years. A second analysis using a second SNP database gave 
similar
    results. That is roughly the same proportion of genes that were altered in 
maize
    when humans domesticated it from its wild ancestors.

Domesticated humans

    Moyzis speculates that we may have similarly domesticated ourselves with the
    emergence of modern civilisation.

    One of the major things that has happened in the last 50,000 years is the
    development of culture, he says. By so radically and rapidly changing our
    environment through our culture, weve put new kinds of selection [pressures] 
on
    ourselves.

    Genes that aid protein metabolism perhaps related to a change in diet with 
the
    dawn of agriculture turn up unusually often in Moyziss list of recently 
selected
    genes. So do genes involved in resisting infections, which would be 
important in
    a species settling into more densely populated villages where diseases would
    spread more easily. Other selected genes include those involved in brain
    function, which could be important in the development of culture.

    But the details of any such sweeping survey of the genome should be treated 
with
    caution, geneticists warn. Now that Moyzis has made a start on studying how 
the
    influence of modern human culture is written in our genes, other teams can 
see if
    similar results are produced by other analytical techniques, such as 
comparing
    human and chimp genomes.

    Journal reference: Proceedings of the National Academy of Sciences (DOI:
    10.1073/pnas.0509691102)

    Evolution Learn more about the struggle to survive in our comprehensive
    [11]special report.

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Weblinks

      * [18]Robert Moyzis, University of California
      * [19]http://www.ucihs.uci.edu/biochem/faculty/moyzis.html
      * [20]SNP fact sheet, Human Genome Project
      * [21]http://www.ornl.gov/sci/techresources/Human_Genome/faq/snps.shtml
      * [22]Evolution special report, New Scientist
      * [23]http://www.newscientist.com/channel/life/evolution

References

   11. http://www.newscientist.com/channel/life/evolution
   12. http://www.newscientist.com/article.ns?id=dn8254
   13. http://www.newscientist.com/article.ns?id=dn8254
   14. http://www.newscientist.com/article.ns?id=mg18725174.600
   15. http://www.newscientist.com/article.ns?id=mg18725174.600
   16. http://www.newscientist.com/article.ns?id=mg18725071.100
   17. http://www.newscientist.com/article.ns?id=mg18725071.100
   18. http://www.ucihs.uci.edu/biochem/faculty/moyzis.html
   19. http://www.ucihs.uci.edu/biochem/faculty/moyzis.html
   20. http://www.ornl.gov/sci/techresources/Human_Genome/faq/snps.shtml
   21. http://www.ornl.gov/sci/techresources/Human_Genome/faq/snps.shtml
   22. http://www.newscientist.com/channel/life/evolution
   23. http://www.newscientist.com/channel/life/evolution