by Brandon Keim
November 29, 2012
from Wired Website
If you could escape the human time scale for a moment, and regard evolution from the perspective of deep time, in which the last 10,000 years are a short chapter in a long saga, you’d say:
Things are pretty wild right now.
In the most massive study of genetic variation yet, researchers estimated the age of more than one million variants, or changes to our DNA code, found across human populations.
The vast majority proved to be quite young. The chronologies tell a story of evolutionary dynamics in recent human history, a period characterized by both narrow reproductive bottlenecks and sudden, enormous population growth.
The evolutionary dynamics of these features resulted in a flood of new genetic variation, accumulating so fast that natural selection hasn’t caught up yet.
As a species, we are freshly bursting with the raw material of evolution.
“Most of the mutations that we found arose in the last 200 generations or so. There hasn’t been much time for random change or deterministic change through natural selection,” said geneticist Joshua Akey of the University of Washington, co-author of the Nov. 28 Nature study.
“We have a repository of all this new variation for humanity to use as a substrate. In a way, we’re more evolvable now than at any time in our history.”
Akey specializes in what’s known as rare variation, or changes in DNA that are found in perhaps one in 100 people, or even fewer.
For practical reasons, rare variants have only been studied in earnest for the last several years. Before then, it was simply too expensive. Genomics focused mostly on what are known as common variants.
However, as dramatically illustrated by a landmark series of papers to appear this year - by Alon Keinan and Andrew Clark, by Matt Nelson and John Novembre, and another by Akey’s group, all appearing in Science, along with new results from the humanity-spanning 1,000 Genomes Project - common variants are just a small part of the big picture.
They’re vastly outnumbered by rare variants, and tend to have weaker effects.
The medical implications of this realization are profound.
The previously unappreciated significance of rare variation could explain much of why scientists have struggled to identify more than a small fraction of the genetic components of common, complex disease, limiting the predictive value of genomics.
'The genetic potential of our population
is vastly different than what it was 10,000 years ago.'
READ MORE
http://www.bibliotecapleyades.net/ciencia/esp_ciencia_life68.htm
November 29, 2012
from Wired Website
If you could escape the human time scale for a moment, and regard evolution from the perspective of deep time, in which the last 10,000 years are a short chapter in a long saga, you’d say:
Things are pretty wild right now.
In the most massive study of genetic variation yet, researchers estimated the age of more than one million variants, or changes to our DNA code, found across human populations.
The vast majority proved to be quite young. The chronologies tell a story of evolutionary dynamics in recent human history, a period characterized by both narrow reproductive bottlenecks and sudden, enormous population growth.
The evolutionary dynamics of these features resulted in a flood of new genetic variation, accumulating so fast that natural selection hasn’t caught up yet.
As a species, we are freshly bursting with the raw material of evolution.
“Most of the mutations that we found arose in the last 200 generations or so. There hasn’t been much time for random change or deterministic change through natural selection,” said geneticist Joshua Akey of the University of Washington, co-author of the Nov. 28 Nature study.
“We have a repository of all this new variation for humanity to use as a substrate. In a way, we’re more evolvable now than at any time in our history.”
Akey specializes in what’s known as rare variation, or changes in DNA that are found in perhaps one in 100 people, or even fewer.
For practical reasons, rare variants have only been studied in earnest for the last several years. Before then, it was simply too expensive. Genomics focused mostly on what are known as common variants.
However, as dramatically illustrated by a landmark series of papers to appear this year - by Alon Keinan and Andrew Clark, by Matt Nelson and John Novembre, and another by Akey’s group, all appearing in Science, along with new results from the humanity-spanning 1,000 Genomes Project - common variants are just a small part of the big picture.
They’re vastly outnumbered by rare variants, and tend to have weaker effects.
The medical implications of this realization are profound.
The previously unappreciated significance of rare variation could explain much of why scientists have struggled to identify more than a small fraction of the genetic components of common, complex disease, limiting the predictive value of genomics.
'The genetic potential of our population
is vastly different than what it was 10,000 years ago.'
READ MORE
http://www.bibliotecapleyades.net/ciencia/esp_ciencia_life68.htm
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