5 Most Incredible Discoveries of the Week

Age-defying trees and a theory about what did in Alexander the Great are among this week's discoveries:

• Trees Grow Faster as They Age: New research that shows large, old trees grow much faster than their younger counterparts—and speed up their growth as they age. In effect, they become stronger as the years go by. It's like finding out the stars on your favorite sports teams are 90-year-olds, says a researcher.
• Alexander the Great Felled by Toxic Wine? One of the greatest mysteries surrounding Alexander the Great—namely, why he died at age 32—may finally have been solved. Turns out, his killer just might be an innocent-looking but poisonous plant.
• Birds' V-Formation Explained: So why do birds fly in those familiar V-formations? A new high-tech study suggests it's all about aerodynamic efficiency, but the precision employed by the birds surprised even the research team.
• Even Deeper 'Grand Canyon' Found Under Antarctic Ice: In August, scientists announced they had found a Greenland canyon that dwarfs the famed one in Arizona. Now, researchers have repeated the feat in the Antarctic—and then some.
• Fish Fossil Challenges a View on Evolution: Conventional wisdom has it that the first creatures to emerge from the water eons ago did so without hind limbs. Conventional wisdom, meet Tiktaalik roseae. This ancient creatures appears to have developed legs, or something like them, while still living in the water.

Click for more incredible discoveries, including one about how coffee might help your long-term memory. (More discoveries stories.)