While the recycling numbers at the bottom of plastic items "are not meant to provide health information or risks, " Dr. Halden says, they can sometimes provide clues to the chemicals in them.

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The words people choose, their movements, or even how quickly they exit a meeting can provide clues to emotion.

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Harrison says that he hopes that data from studies of humans taking mTOR drugs might also provide clues, although they may be difficult to tease out: Patients with cancer or those undergoing transplant, the people who get mTOR drugs now, don't tend to die of old age.

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