Physicians typically prescribe a seven- to 10-day antibiotic regimen for pneumonia. A double-blind study, however, shows that a three-day treatment is just as effective.

BMJ, June 10

A 300-mile-wide crater under the Antarctic ice may be the evidence that an object 30 miles wide caused the earth's greatest mass extinction 250 million years ago. The one that polished off the dinosaurs was about one fifth that size.

American Geophysical Union Joint Assembly, Baltimore, May 23–26

And good for covering up, too: Fig trees may have marked the beginning of agriculture 11,400 years ago. Based on finds in the lower Jordan Valley, figs were domesticated 1,000 years before wheat, barley and legumes.

Science, June 2

Scientists discovered a few years ago that the mammalian heart has stem cells. Now, in a step toward using stem cells in cardiac repair, they have found where they lurk, based on mouse studies: in small niches near heart muscle cells.

Proceedings of the National Academy of Sciences USA, June 13