Spicy food connoisseurs know that when it comes to spicy peppers, the sometimes painful burning sensation is part of the draw.
Humans are one of the few species on Earth that actively seek out spicy foods as most mammals avoid eating hot peppers and plants because of the pain that comes with them.
Chili peppers and other spicy plants get their heat from a chemical called capsaicin, which is designed to deter animals from eating them. However, a new study found that Chinese tree shrews (Tupaia belangeri chinensis) have evolved to thrive on spicy peppers full of capsaicinoids.
Researchers from Kunming Institute of Zoology in China in a new study unlocked the secrets behind the shrew’s tolerance to capsaicin and it has to do with a mutation in the animal’s cell receptors.
The study was published in the journal PLOS BIOLOGY.
Capsaicinoids trigger a burning sensation by activating an ion channel found on the surface of pain-sensitive cells called TRPV1.
The chemical is meant to act as a defense mechanism by alerting whatever consumes it that the food is dangerous.
The researchers fed both mice and tree shrews chili peppers which contain capsaicin. The mice reduced the amount of pepper they ate as they realized how hot the food was whereas the shrews were not deterred.
Even though the mice and shrews had similar levels of TRPV1, the ion channels in shrews were less responsive to the chemical because shrews lacked a single amino acid that was found in the mice.
This is why tree shrews are unaffected by capsaicin and can feed on foods that other species would find painful.
The researchers theorize that this mutation developed to allow tree shrews to eat Piper boehmeriaefolium, a plant in their environment that produces heavy amounts of capsaicin.
“We propose that this mutation is an evolutionary adaptation that enabled the tree shrew to acquire a tolerance for capsaicinoids, thus widening the range of its diet for better survival,” said Yalan Han, the lead author of the study.
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