The research team used yeast chromosome No. 3 as the model for their biochemical stitchery. Pins and white diamonds in the illustration represent "designer changes" not found in the usual No. 3; yellow stretches represent deletions.
Until recently, finding characteristic stone and bone tools was the only way to trace the fate of the Clovis people, whose culture appeared in North America about 13,000 years ago.
Sarah L. Anzick/Nature
Massive sections of ice (center front) have broken away from the Jakobshavn glacier into the sea. There's enough water stored in Greenland's glaciers to raise the sea level by 20 feet.