SCIENCE

"The Chicxulub impact alone could not have caused the mass extinction because this impact predates the mass extinction," said Keller, who will present the research tomorrow at the Geological Society of America's annual meeting in Philadelphia. "We cannot attribute any specific extinctions to this impact."

Keller and colleagues from Switzerland and Germany believe it was the second, larger impact that left the layer of the metal iridium in rocks the world over and was the final blow for dinosaurs and other animals. Just where it struck, they don't know.

-- Christopher Lee

Darwin Evolves on the Web

Call it extreme evolution: Now you can read Charles Darwin's handwritten journals on the Internet, gaze upon digitized images of his original drawings and even listen to podcasts of his works.

Proving that the King of Evolution is still evolving, the University of Cambridge last week announced it is making Darwin's complete works available free on the Web, including 50,000 pages of searchable text and 40,000 images.

Much of the material (visible at http://www.darwin-online.org.uk ) has never been published before. It was compiled by project director John van Wyhe, who spent four years cajoling libraries and other sources around the world to contribute scans of their holdings. Most text pages are visible as both originals and as transcriptions in modern type.

But why stop there?

"There's no reason why, if you can search and read the text and look at images of the original, you shouldn't be able to download and listen to it as well," van Wyhe said. So with the help of text-recognition software, the material is also available as MP3 audio files that can be burned onto CDs or loaded onto iPods.

Listen up: "It may be said that natural selection is daily and hourly scrutinizing, throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working."

Those were the man's words back in 1859, as he took pen to paper and began the work that he would eventually title "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life."

Darwin recognized natural selection for the ruthless pruner it is. But so far, at least, his family has made the cut. The new Web site was introduced at a ceremony Friday featuring Randal Keynes -- Darwin's great-great-grandson.

-- Rick Weiss