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Science Daily — Despite the explosive growth in size and complexity of the human brain, the pace of evolutionary change among the thousands of genes expressed in brain tissue has actually slowed since the split, millions of years ago, between human and chimpanzee, an international research team reports in the December 26, 2006, issue of the journal, PLOS Biology.

The rapid advance of the human brain, the authors maintain, has not been driven by evolution of protein sequences. The higher complexity of the biochemical network in the brain, they suspect, with multiple gene-gene interactions, places strong constraints on the ability of most brain-related genes to change.

“We found that genes expressed in the human brain have in fact slowed down in their evolution, contrary to some earlier reports,” says study author Chung-I Wu, professor of ecology and evolution at the University of Chicago. “The more complex the brain, it seems, the more difficult it becomes for brain genes to change. Calibrated against the genomic average, brain-expressed genes in humans appear to have evolved more slowly than in chimpanzee or old-world monkey.”

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A variation of a gene that controls the size of cholesterol molecules in the bloodstream is common among elderly Ashkenazim who remain mentally sharp.

If you live to 100, as roughly one in every 10,000 people do, you will likely want both your mind and body intact. Researchers have now discovered a gene that accomplishes just that, apparently protecting the brain as well as prolonging life.

The Longevity Genes Project, initiated by Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine, investigates people who live exceptionally long lives.

“There’s a strong family history of longevity in these people,” says Barzilai. “Research has shown the odds of having exceptional longevity are about 10 to 18 times more if you have a centenarian in your family. And these usually aren’t vegetarians or professional athletes. Some have smoked for 90 years.”

Barzilai and his colleagues examined 158 people of Ashkenazi, or Eastern European Jewish, descent who were 95 years of age or older. They chose Ashkenazi Jews since current generations stem from a relatively limited number of ancestors. This means they have a comparatively uniform genetic makeup, making it easier to identify important genetic differences.

The scientists gave these volunteers a common test of mental function, consisting of 30 questions. Correctly answering 25 of the questions meant a subject passed the test. Those centenarians who passed were two to three times more likely to have a common variant of a particular gene, called the CETP gene, than those who did not. When the researchers studied another 124 Ashkenazi Jews between 75 and 85 years of age, those subjects who passed the test of mental function were five times more likely to have this gene variant than their counterparts.

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The smallest form of life known to science just got smaller.

Four million of a newly discovered microbe — assuming the discovery, reported yesterday in the journal Science, is confirmed — could fit into the period at the end of this sentence.

Scientists found the microbes living in a remarkably inhospitable environment, drainage water as caustic as battery acid from a mine in Northern California. The microbes, members of an ancient family of organisms known as archaea, formed a pink scum on green pools of hot mine water laden with toxic metals, including arsenic.

“It was amazing,” said Jillian F. Banfield of the University of California, Berkeley, a member of the discovery team. “These were totally new.” In their paper, the scientists call the microbes “smaller than any other known cellular life form.”

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– this story is from the NY Times which requires an ID and PW to login. You just have to sign up once to get these and they are free.

– It’s been the general wisdom that New Zealand did not have any native mammals other than one or two bats. Now, scientists have found fossils of a small mammal from 16 million years ago and they are having to do a rethink.

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The discovery of fossils from a waddling, mouse-sized mammal in a New Zealand lake bed has stunned scientists, and could force a “rethink” on the evolution of this country’s animals.
The bones from the primitive mammal, described as unlike any mammal alive today, were discovered in sediment at least 16 million years old. They suggest the mammal was mouse-sized and walked by waddling.

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Nasa says it has found “compelling” evidence that liquid water flowed recently on the surface of Mars.The finding adds further weight to the idea that Mars might harbour the right conditions for life.

The appearance of gullies, revealed in orbital images from a Nasa probe, suggests that water could have flowed on the surface in the last few years.

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