Thursday, March 29, 2007

Non-archaeology post No need to thank dinosaur-killing asteroid for mammalian success
It is a natural history tale that every third grader knows: The dinosaurs ruled the Earth for hundreds of millions of years, until an asteroid struck the Yucatan Peninsula and triggered a mass extinction that allowed the ancestors of today’s mammals to thrive.

The asteroid part of the story may still hold true, but a new study published in the March 29 issue of the journal Nature challenges the prominent hypothesis that a mass extinction of dinosaurs 65 million years ago played a major role in the diversification of today’s mammals.

. . .

"The previous evidence showed that we did see a die-off of the dinosaurs and an increase in the rise of the mammals roughly 65 million years ago," Gittleman said. "But the fossil record, by its very nature, is patchy. We have found that when you fuse all of the molecular trees with the fossil evidence, the timing does not work. The preponderance of mammals really didn’t take off until 10 to 15 million years after the demise of the dinosaurs."

I wonder if there is still some delay effect. It's been hypothesized that the Cambrian explosion had its roots much earlier.

See also: Ewwwww! UCLA anthropologist studies evolution's disgusting side
Behind every wave of disgust that comes your way may be a biological imperative much greater than the urge to lose your lunch, according to a growing body of research by a UCLA anthropologist.

"The reason we experience disgust today is that the response protected our ancestors," said Dan Fessler, associate professor of anthropology and director of UCLA’s Center for Behavior, Evolution, and Culture. "The emotion allowed our ancestors to survive long enough to produce offspring, who in turn passed the same sensitivities on to us."