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Transcript¹

 This is Scientific American's 60-Second Science. I'm Cynthia Graber . This will just take a minute.

Some peppers have a mild, fresh flavor. But others burn your lips and leave a lingering, numbing² kick. If you enjoy that tingling³ thrill, you might want to say thanks. But not to the peppers themselves—to bugs⁴. Peppers are tasty so they’ll be eaten and have their seeds dispersed⁵. But the snacker has to be the right creature—which the peppers need to be birds. Some insects also like to munch⁶ peppers, and they may puncture⁷ the skin. The wound leaves an opening for a microbial fungus⁸. The fungus wriggles⁹ inside and snacks on the seeds, destroying them.

Researchers from the U.S. and Bolivia tested whether a pepper’s heat offers it protection. They published August 11th in the Proceedings¹⁰ of the National Academy of Sciences. First, they collected chilies¹¹ from seven populations of the same pepper species over a thousand-mile area. Then they counted insect-induced scars and tested pepper heat. In regions with lots of insects, and a greater risk of death by microbe, plants tended to be much hotter. And the hot chemicals, called capsaicinonids, slow microbial growth. Birds can’t sense capsaicin. So the hot peppers kill bugs, and still attract birds. And many humans, too.

Thanks for the minute for Scientific American's 60-Second Science. I'm Cynthia Graber .