"It's highly tied to the fight or flight response, " says George Preti, a faculty member at Monell Center.

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The Monell team suggests this natural early flavour exposure serves to establish flavours of the mother's diet as acceptable and preferred.

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"It's a first-warning system that we have for danger, " says Pamela Dalton, faculty member at Monell Chemical Senses Center, a scientific-research institution.

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In one corner of this tent, Paul Breslin, who works at the Monell Institute in Philadelphia, watched over several tables where twins sat sipping clear liquids from cups and making notes.

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Recent research is finding that taste receptors are found all over the body, including in the gut, nose, and brain, says Danielle Reed, a member at Monell Chemical Senses Center in Philadelphia.

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"For most of human history, people didn't have enough to eat, so fat was something you really needed to seek out, " says Marcia Pelchat, a food psychologist at the Monell Chemical Senses Center in Philadelphia.

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Also at Monell Center, faculty member Pamela Dalton showed that stress levels decreased faster when people were exposed to the body odor of a family member rather than that of a stranger or a neutral fragrance.

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For example, a recent study by researchers at the University of Pennsylvania and the Monell Center showed that supertasters were better able to fend off bacterial sinus infections because of a particular bitter-taste receptor in their nose.

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There is no hard evidence that the same kinds of pheromones found in animals also exist in humans, said Charles Wysocki, researcher at the Monell Chemical Senses Center in Philadelphia, Pennsylvania, and adjunct professor at the University of Pennsylvania.

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