[Paleopsych] New Scientist: Civilisation has left its mark on our genes
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Civilisation has left its mark on our genes
* 22:00 19 December 2005
* Bob Holmes
Darwins fingerprints can be found all over the human genome. A detailed look
human DNA has shown that a significant percentage of our genes have been
by natural selection in the past 50,000 years, probably in response to
modern human culture such as the emergence of agriculture and the shift
living in densely populated settlements.
One way to look for genes that have recently been changed by natural
to study mutations called single-nucleotide polymorphisms (SNPs)
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
selection favours a particular variant of a gene, causing the SNPs nearby to
selected as well.
Robert Moyzis and his colleagues at the University of California, Irvine,
searched for instances of linkage disequilibrium in a collection of 1.6
SNPs scattered across all the human chromosomes. They then looked carefully
the instances they found to distinguish the consequences of natural
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
human genome, have changed under the influence of natural selection within
past 50,000 years. A second analysis using a second SNP database gave
results. That is roughly the same proportion of genes that were altered in
when humans domesticated it from its wild ancestors.
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]
Genes that aid protein metabolism perhaps related to a change in diet with
dawn of agriculture turn up unusually often in Moyziss list of recently
genes. So do genes involved in resisting infections, which would be
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
caution, geneticists warn. Now that Moyzis has made a start on studying how
influence of modern human culture is written in our genes, other teams can
similar results are produced by other analytical techniques, such as
human and chimp genomes.
Journal reference: Proceedings of the National Academy of Sciences (DOI:
Evolution Learn more about the struggle to survive in our comprehensive
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* Evolution: Blink and you'll miss it
* 09 July 2005
* Robert Moyzis, University of California
* SNP fact sheet, Human Genome Project
* Evolution special report, New Scientist
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