The orange layer inside this pepper contains capsaicin

Alan Alda loves spicy food. His predilection for pepper prompted us to ponder the fiery nature of the chile, such a close relative of the benign bell pepper. Why are chile peppers hot?

Dr. Paul Bosland, director of the Chile Pepper Institute in Las Cruces, New Mexico, has the answer: an orange-colored compound called capsaicin. Its burning flavor discourages mammals from eating the plant, but has no effect on birds. It turns out that the chile relies on birds to spread its seeds - in the digestive tract of a mammal, the seeds are simply destroyed. The pepper's self-defense strategy, however, is completely lost on Alan and millions like him, who relish the heat of capsaicin.

Paul Bosland awaits Alan's reaction to the three-alarm chili

Paradoxically, another side affect of capsaicin has led to some astonishing results. Researchers discovered that capsaicin burns only at first, then eventually deadens the pain sensors in the mouth. Anesthesiologist Wendye Robbins wondered if it could have the same effects elsewhere in the body. Alan visits her lab as she tests her capsaicin-based analgesic cream on a patient who suffers from crippling foot pain. The capsaicin certainly burns at first, despite the patient's local anesthetic. But once the compound numbs his pain receptors, his feet no longer ache. Within a week of the treatment, the formerly bed-ridden althete is up and running.

For more on this topic, see the web feature:
"Eureka!"