That would be devolution!
Posted on 12/29/2004 9:14:28 AM PST by aculeus
Emergence of society may have spurred growth
The sophistication of the human brain is not simply the result of steady evolution, according to new research. Instead, humans are truly privileged animals with brains that have developed in a type of extraordinarily fast evolution that is unique to the species.
"Simply put, evolution has been working very hard to produce us humans," said Bruce Lahn, an assistant professor of human genetics at the University of Chicago and an investigator at the Howard Hughes Medical Institute.
"Our study offers the first genetic evidence that humans occupy a unique position in the tree of life."
Professor Lahn's research, published this week in the journal Cell, suggests that humans evolved their cognitive abilities not owing to a few sporadic and accidental genetic mutations - as is the usual way with traits in living things - but rather from an enormous number of mutations in a short period of time, acquired though an intense selection process favouring complex cognitive abilities.
Evolutionary biologists generally argue that humans have evolved in much the same way as all other life on Earth. Mutations in genes from one generation to the next sometimes give rise to new adaptations to a creature's environment.
Those best adapted to their environment are more likely to survive and pass on their genes to the next generation.
The evolution of a large brain in humans, then, can be seen as similar to the process that leads to longer tusks or bigger antlers. In general terms, and after scaling for body size, brains get bigger and more complex as animals get bigger.
But with humans, the relative size of the brain does not fit the trend - our brains are disproportionately big, much bigger even than the brains of other non-human primates, including our closest relatives, chimpanzees.
Prof Lahn's team examined the DNA of 214 genes involved in brain development in humans, macaques, rats and mice.
By comparing mutations that had no effect on the function of the genes with those mutations that did, they came up with a measure of the pressure of natural selection on those genes.
The scientists found that the human brain's genes had gone through an intense amount of evolution in a short amount of time - a process that far outstripped the evolution of the genes of other animals.
"We've proven that there is a big distinction," Prof Lahn said. "Human evolution is, in fact, a privileged process because it involves a large number of mutations in a large number of genes.
"To accomplish so much in so little evolutionary time - a few tens of millions of years - requires a selective process that is perhaps categorically different from the typical processes of acquiring new biological traits."
As for how all of this happened, the professor suggests that the development of human society may be the reason.
In an increasingly social environment, greater cognitive abilities probably became more of an advantage.
"As humans become more social, differences in intelligence will translate into much greater differences in fitness, because you can manipulate your social structure to your advantage," he said.
"Even devoid of the social context, as humans become more intelligent, it might create a situation where being a little smarter matters a lot.
"The making of the large human brain is not just the neurological equivalent of making a large antler. Rather, it required a level of selection that's unprecedented."
Guardian Unlimited © Guardian Newspapers Limited 2004
Translation: Women like guys with brains
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Which version are you talking about, micro or macro?
Whut R U tryin' 2 say???
Micro or macro? Which? There's a MAJOR difference.
The fossil record shows no transitory fossils which has led to kooky theories like Punctuated Equillibrium.
Granted the fossil record may be incomplete. But is it incomplete because we have yet to find the illusive transitory fossils or is it complete because there are no transitory fossils?
Ya think? Interesting nobody ever thought of that before.
That would be devolution!
The sum total of intelligence shared among humans is constant. The population is rising.
They are gaining resistance to the drugs. Its still the same virus. When you get a shot to become resistant to a virus we don't call you Homo Saipian+. No you are still a Homo Saipian. There are better arguments than this.
Incomplete? You could put the whole 4 million year collection on a couple shelves in your study library. The fossil record has more gaps than George Washington's upper jaw.
"Simply put, evolution has been working very hard to produce us humans,"
What an odd statement for an evolutionary biologist. Should "evolution" be capitalized?
What's interesting is that there are people who will entertain the possibility that aliens created homo sapiens, but absolutely refuse to entertain the possibility that God had something to do with our origin.
Thanks for the ping!
We Are DEVO
1:26 Then God said, "Let Us make man in Our image, according to Our likeness; and let them rule over the fish of the sea and over the birds of the sky and over the cattle and over all the earth, and over every creeping thing that creeps on the earth."
1:27 God created man in His own image, in the image of God He created him; male and female He created them.
1:31 God saw all that He had made , and behold, it was very good . And there was evening and there was morning, the sixth day.
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