THE BORE
General => The Superdeep Borehole => Topic started by: Flannel Boy on March 28, 2007, 04:14:17 PM
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Human evolution has been speeding up tremendously, a new study contends—so much, that the latest evolutionary changes seem to largely eclipse earlier ones that accompanied modern man’s “origin.”
Hawks and Cochran also analyzed past genetic studies to estimate the rate of production of genes that undergo positive selection—that is, genes that spread because they are beneficial. “The rate of generation of positively selected genes has increased as much as a hundredfold during the past 40,000 years,” they wrote.
A “thing that should probably worry people is that brains have been getting smaller for 20,000 to 30,000 years,” said Cochran. But brain size and intelligence aren’t tightly linked, he added. Also, growth in more advanced brain areas might have made up for the shrinkage, Cochran said; he speculated that an almost breakneck evolution of higher foreheads in some peoples may reflect this. A study in the Jan. 14 British Dental Journal found such a trend visible in England in just the past millennium, he noted, a mere eyeblink in evolutionary time.
Research published in the Sept. 9, 2005 issue of the research journal Science by Lahn and colleagues found that two genes linked to brain size are rapidly evolving in humans.
Anthropologist Jeffrey McKee of Ohio State University said the new findings of accelerated evolution bear out predictions he made in a 2000 book The Riddled Chain. Based on computer models, he argued that evolution should speed up as a population grows. This is because population growth creates more opportunities for new mutations; also, the expanded population occupies new environmental niches, which would drive evolution in new directions.
Lahn said he’s not convinced that the accelerated physical evolution is tied to population growth. “It may be a long way before” anyone can test the truth of this, he wrote.
But other factors could also explain an acceleration, according to anthropologist John Kingston of Emory University in Atlanta, Ga. Evolution might speed up because we have changed our own environment, which in turn changes the evolutionary pressures. “We now control our own environment and ecology to some extent,” he said.
For instance, if you invent spears, you perhaps can afford to be slighter-framed because you can stand further away from wild animals, Cochran said. He argued that a powerful synergy between these sorts of changes and expanding population explains the “fantastically rapid” recent evolution.
“A very big change”
Overall, the findings could amount to “a very big change” in traditional thinking for two reasons, according to McKee. First, he said, many researchers had mistakenly assumed population growth would slow down evolution, because new mutations would take too long to spread through a large population.
Second, the findings deal a final blow to a lingering view among anthropologists of evolution as a ladder “with us as the be-all-end-all,” he said. That idea went out of fashion in the 1950s but still persists “in the backs of our minds,” he added.
Many of the changes found in the genome or fossil record reflect metabolic alterations to adjust to agricultural life, Cochran said. Other changes simply make us weaker.
In the June 2003 issue of the research journal Current Anthropology, Helen Leach of the University of Otago, New Zealand wrote that skeletons from some populations in the human lineage have undergone a progressive shrinkage and weakening, and reduction in tooth size, similar to changes seen in domesticated animals. Humans seem to have domesticated themselves, she argued, causing physical as well as mental changes.
Despite all the alterations, McKee said he believes the notion of an “origin” of modern humans around 200,000 years ago remains useful. “It’s just a threshold point” at which humans take on most of the physical features we recognize, he remarked, and as such, needn’t be discarded. Cochran said it can still be argued that the key change was language; but when this originated remains far from clear.
Whatever the implications of the recent findings, McKee added, they highlight a ubiquitous point about evolution: “every species is a transitional species.”
http://www.world-science.net/exclusives/070326_evolution.htm (http://www.world-science.net/exclusives/070326_evolution.htm)
bobobobo (http://www.latribunedelart.com/Expositions_2004/Rubens_-_Adam_et_Eve.JPG)
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Thank transfats!
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:-[
Like you'll ever pass on your autistic genes.
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There's a good chance my kids won't get what I have? Ok I guess that's positive.
he means you'll be too busy spinning plates to look at a lady.
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DONT CHANGE THIS THREAD IN ANOTHER RUZBEH HAS AUTISM THREADS YOU FUCKING TURDS
(http://www.elainechen.com/illustration/assets/autism.gif)
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DONT CHANGE THIS THREAD IN ANOTHER RUZBEH HAS AUTISM THREADS YOU FUCKING TURDS
(http://www.elainechen.com/illustration/assets/autism.gif)
:LOL
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*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?
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*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?
I too would like to know this.
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I just wanna be able to fly
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*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?
Richard Dawkins' books are pretty well written. Selfish Gene especially.
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i don't see any reference to the almighty in those explanations
why do you hate the troops, malek
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^it's an old ass thread man. I was searching for something else.
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*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?
Richard Dawkins' books are pretty well written. Selfish Gene especially.
Damn this thread is old. It's funny you said this, I just finished that and The Blind Watchmaker last month.
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This graph is from the Economist. Pay no attention to the recent drop off. But overall you can see that human evolution has accelerated over the past 80,000.
(http://www.economist.com/images/20071215/CST912.gif)