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A tiny ladderlike beam of silicon converts light into vibrations and vice versa with extremely high efficiency

A new study finds support for the "grandmother hypothesis," the idea that older women spread their genes most effectively by helping their daughters take care of their children.

Thus paternal grandmothers were most beneficial to the survival of their granddaughters and least beneficial to the survival of their grandsons, while maternal grandmothers showed an intermediate effectiveness. Experts are thrilled by the findings. "Wow, very interesting," says Hawkes. "The consistent results across seven populations ... seem to clarify previously inconsistent results." Lorena Madrigal, an anthropologist at the University of South Florida in Tampa, calls the study "an important contribution to a topic of great interest to evolutionary biologists."

A deep hole on the moon that could open into a vast underground tunnel has been found for the first time. The discovery strengthens evidence for subsurface, lava-carved channels that could shield future human colonists from space radiation and other hazards.

By taking a few well-known, readily available measures, researchers argue, Americans could cut their emissions of the greenhouse gas carbon dioxide by as much as 7% over the next decade.