| Topic: |
Religions > Atheism |
| User: |
"johac" |
| Date: |
10 Mar 2006 01:36:43 AM |
| Object: |
Hundreds of human genes still evolving |
Look, Ma! I'm evolving!
Sorry, fundies.
---
Hundreds of human genes still evolving
Study links genetic changes to major events in human history
By Ker Than
LiveScience
Updated: 4:50 p.m. ET March 8, 2006
A comprehensive scan of the human genome finds that hundreds of our
genes have undergone positive natural selection during the past 10,000
years of human evolution.
Genes are the instructions organisms use to make proteins. They are
encoded in genetic material, usually DNA, and some come in different
versions, called alleles." Positive natural selection occurs when one
allele is favored over another due to changes in the environment.
Researchers from the University of Chicago analyzed the genomes of 209
unrelated individuals from three distinct human populations: East
Asians, Europeans and Yorubans from Nigeria. Each population contained
roughly 250 positively selected genes; however, most of the affected
genes differed depending on the group.
This study addresses the question 'Are humans still evolving?', and the
answer is 'Absolutely,'" study team member Benjamin Voight told
LiveScience.
Other studies have also reached the same conclusion.
Links to history
The new study links genetic changes to major events in the history of
our species.
There have been a lot of recent changes the advent of agriculture,
shifts in diet, new habitats, climatic changes over the past 10,000
years," said Jonathan Pritchard, a human geneticist at the University of
Chicago who led the study.
Many genes were found to be evolving in all three of the human
populations studied. The specific functions of many of the genes are not
known, but the researchers were able to separate them into broad
categories. These categories include:
# Olfaction: the researchers found many genes important for taste and
smell
# Reproduction: involved in things like sperm mobility and egg
fertilization
# Increasing brain size
# Bone development and skeletal changes
# Carbohydrate metabolism: positive selection was observed for genes
involved in breaking down mannose in Yorubans, sucrose in East Asians,
and lactose for Europeans. (Mannose is a sweet secretion found in some
trees and shrubs, sucrose is common table sugar, and lactose is a sugar
found in milk.)
# Disease resistance and pathogen protection
# Metabolism of foreign compounds, such as exotic plant proteins or
animal toxins
A tradeoff
The researchers also found positive selection in four pigment genes
important for lighter skin in Europeans that were not known before.
Scientists think humans evolved lighter skin in Europe as an adaptation
to less sunlight.
And in East Asians, they found strong evidence of positive selection in
genes involved in the production of alcohol dehydrogenase (ADH), a
protein necessary for breaking down alcohol. Many East Asians can't
metabolize alcohol because they carry a mutation that prevents them from
making ADH. The new finding suggests that the mutation may confer some
currently unknown additional benefit.
The study, which used data collected by the International HapMap
Project, is detailed in the March 7 issue of the journal Public Library
of Science-Biology.
---
http://msnbc.msn.com/id/11730456/
Also:
Mining the human genome for signs of recent selection
http://www.eurekalert.org/pub_releases/2006-03/plos-mth030206.php
Scan of human genome reveals evidence of more than 700 recently evolving
genes
http://www.eurekalert.org/pub_releases/2006-03/uocm-soh030206.php
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
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