Civilisation Has Left Its Mark On Our Genes

New Scientist ^ | 12-19-2005 | Bob Holmes

[blam]

Civilisation has left its mark on our genes

22:00 19 December 2005
From New Scientist Print Edition
Bob Holmes

Darwin’s 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, we’ve 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 Moyzis’s 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)

[ndt]

"Why are there no transitional species"

There are, all of them are transitional species.

[From many - one.]

Neat.

Disease resistance is something one would expect but the protein metabolism thingy is a bit counter-intuitive.

Maybe more meat as humans became better hunters as they got smarter?

[blam]

"Maybe more meat as humans became better hunters as they got smarter?"

Animal domestication.

[From many - one.]

That's less than 10,000 I think, although adding in herding should make it longer.

I suspect two possible countervailing trends... first an increase in protein supply with more efficiency, then, when agriculture came in, a dimuition as grains replaced meat.

[adorno]

Well it's not doing a very good job, the vast majority of species are extinct.

What are you talking about when you say "it's not doing"? Evolution or intelligent design?

[From many - one.]

10,000 = 10,000 years

[ndt]

"What are you talking about when you say "it's not doing"? Evolution or intelligent design?"

That would be ID.

If some designer were intelligently molding species to fit their changing niches, it (the designer) is a miserable failure since the vast majority of species that have ever lived are currently extinct.

On the other hand that is exactly what you would expect from evolution/natural selection. If a a species fails to adapt to a changing environment it goes extinct, which just leaves a hole that gets filled by the first species that can survive there.

[GOPPachyderm]

"Because evolution doesn't happen in huge multi-gene mutational leaps."

But isn't that the definition of punctuated equilibrium?

[adorno]

If some designer were intelligently molding species to fit their changing niches, it (the designer) is a miserable failure since the vast majority of species that have ever lived are currently extinct.

Extinction might also be part of the design. In place of the extinct species, you will most likely find a better or improved species. Extinction and dying are all part of the design. Species improvement or redesign might all be part of the plan of an intelligent designer. At the same time, environment design (via the Designer) enters the picture where a species needs to establish itself and prosper.

On the other hand that is exactly what you would expect from evolution/natural selection. If a a species fails to adapt to a changing environment it goes extinct, which just leaves a hole that gets filled by the first species that can survive there.

Evolution/natural selection are terms used by scientists to try to explain observations. Those observations might be explained just as well by insertion of an Intelligent Designer. Intelligent design, which we humans may someday be capable of doing ourselves, could explain a whole lot better the natural selection and observations that scientists keep trying to explain away with "evolution".

Believe me, I have come full-circle in my beliefs. Brought up Catholic, became sciientifically minded from college on and even became an agnostic, some would even say atheist. Deep critical thinking, not faith, has made me re-think my "evolution" and anti-God beliefs. My mind is still evolving and so are my beliefs.

[LiteKeeper]

YEC INTREP

[SunkenCiv]

Thanks Blam. No ping, just adding to the catalog. :')

To all -- please ping me to other topics which are appropriate for the GGG list. Thanks.

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[From many - one.]

No. Not even remotely.

[GOPPachyderm]

Could you explain a litte further? Wouldn't there have to be new genetic information to explain the theory of punctuated equilibrium?

[From many - one.]

Glad to try.

First, so I know where you're coming from, can you give me some idea of your understanding of "new genetic information"

[Lester Moore]

From the article above we get: "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."

From other scientists we get

ITHACA, N.Y. -- Nearly 99 percent alike in genetic makeup, chimpanzees and humans might be even more similar were it not for what researchers call "lifestyle" changes in the 6 million years that separate us from a common ancestor.

...Clark emphasizes that a study like this cannot prove that the biology of humans and chimps differ because of this or that particular gene. "But it generates many hypotheses that can be tested to yield insight into exactly why only 1 percent in DNA sequence difference makes us such different beasts," he says. link here: [http://www.news.cornell.edu/releases/Dec03/chimp.life.hrs.html],

Is it not amazing that modern man is genetically closer to chimpanzees than he is to man 50,000 years ago.

[SkyDancer]

to what?
What are you transitioning too :)

[SkyDancer]

Your opinion ....

[SkyDancer]

So you believe then we're all related and somehow evolved from some molecules that happened to bump into each other .... this begs the question ... where did the original molecules come from and at what point did "whatever being" decide it's more fun to mate than split???

[ndt]

"What are you transitioning too :)"

I'm still working on the mixing genes part. We'll have to wait at least 9 month to answer that question.

But seriously, I was making the point assuming common decent to be true (which I take it you disagree with) then ALL fossils are transitional fossils. Every organism that has ever lived, barring an untimely death, is a midpoint between its ancestors and its descendants.

[SkyDancer]

Great ... hope things turn out the way you want (ie gender)

Problem is with fossils is that there are too many gaps ... secondly a lot is based on uniformitism ... the layers of the earth being laid down uniformly. Such though is not the case - we find younger transitional forms in layers containing older fossils ... so we still really don't know ... then too, all the age names are wrong too - it's been found that forms belonging to one age were found in another - and that's not been corrected.

Have a great Holiday ...

jane