Millions of acres of Conservation Reserve Land bloomed, supplying a healthy mix of blossoms to thousands of honeybee colonies.

CNN: What's killing the bees

Also, while a healthy economy might initially reassure investors, it also decreases the chance that the Federal Reserve will lower rates before the end of 2007 -- stable or even higher rates could worsen credit problems, especially in the battered U.S. housing sector.

FORBES: In Europe, Risk Aversion

Fueling the growing confidence in stocks is a sense that the U.S. economy is healthy enough that recession isn't a concern but not so strong that the Federal Reserve will pull back on its aggressive measures to ease monetary policy.

WSJ: Dow Closes Above 15000

Gary Landreth, one of the authors of Thursday's Science paper and a professor of neurosciences at Case Western Reserve University in Cleveland, said he expected to begin a safety study in 12 healthy patients next month, but there weren't any current plans for a larger clinical trial.

WSJ: Alzheimer's Families Clamor for Drug