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News from the natural world.

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Following the corn flow

Corn was first domesticated in Mexico about 9,000 years ago, but the speed and direction of its spread through the Andes remains a mystery.

Now an international team of scientists has found evidence that maize was grown and processed in Peru between 3,600 and 4,000 years ago - roughly 1,000 years earlier than previous excavations had shown.

The team, led by the Smithsonian Institution's Linda Perry, excavated a house in the southern Peruvian highlands that contained tiny, fossilized particles of maize. Scientists also found arrowroot, which grows in the Amazon rain forest, and not at the altitude where the house was excavated. The arrowroot may be one of the earliest examples of trade between highland and lowland regions that would become a hallmark of later, more sophisticated, Andean civilizations.

The results appear in Thursday's issue of the journal Nature.

Sagebrush sends a warning signal

Move over Paul Revere - meet Atemisia tridentata, alias sagebrush.

Biologists at Cornell University have found that when predators munch on the shrub, it releases volatile organic compounds into the air, warning nearby plants of danger. The scientists found that wild tobacco plants can detect the compounds and begin to "prime" their own natural defenses against predators. The tobacco plant won't actually activate its defenses until it's attacked; the effort is too costly in energy and nutrients for false alarms. But the priming does allow it to respond more quickly to attack when it happens.

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