When dragonflies mate, their tails form a love heart.
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Kissing releases masses of oxytocin, a "love potion" that helps couples bond and feel more attracted to each other.
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Holding hands with someone you love can alleviate physical pain as well as stress and fear.
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Ten seconds of hugging a day increases levels of oxytocin, which can reduce blood pressure, thus cutting the risk of heart disease.
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