After a year and a half characterized by a devastating pandemic and a Herculean effort to develop several highly effective vaccines, this year’s Nobel Prize in Physiology or Medicine was something of a surprise. It was awarded for discoveries related to how the human body senses temperature and touch.

The prize went to David Julius of the University of California, San Francisco, and Ardem Patapoutian of Scripps Research in La Jolla, Calif., for discovering the molecular bases of how nerves convert stimuli—the burn of a chili pepper, or the soft pressure of a hug—into signals that can be sensed by the brain.

Humans’ abilities to sense heat, cold, pressure and position are vital for perceiving and reacting to our surroundings. Understanding how they work is critical for treating chronic pain and other conditions.

“The work by David Julius and Ardem Patapoutian has unlocked one of the secrets of nature,” said Patrik Ernfors, a member of the Nobel Committee, in a press conference announcing the award on Monday in Sweden.

David Julius and Ardem Patapoutian
The Nobel Prize in Physiology or Medicine 2021 was awarded jointly to David Julius and Ardem Patapoutian “for their discoveries of receptors for temperature and touch.” Credit: Niklas Elmehed © Nobel Prize Outreach

U.C.S.F.’s Julius and his colleagues worked to find the receptor for capsaicin, a component in chilies that causes a painful burning sensation. They identified the gene that encodes a new protein, called TRPV1—an ion channel in the membranes of cells that opens in response to heat. Julius got the idea to do his capsaicin experiments while shopping in a grocery store: “Walking through the supermarket aisle one day, seeing all these hot chili pepper sauces, et cetera, I was thinking, ‘We really have to get this project done,” he said in a press conference on Monday. “And my wife said, ‘Well, then you should get on it!’”

Julius and Patapoutian independently identified another protein: TRPM8, which is sensitive to cold and menthol. Additionally, Patapoutian and his colleagues identified the genes for proteins that sense touch, known as Piezo1 and Piezo2. He showed that these two proteins were force-activated ion channels. Piezo2 was also found to be important for sensing the positions of limbs in space, an ability known as proprioception.

Patapoutian, an Armenian-American who grew up in war-torn Lebanon before coming to the U.S. at age 18, says he has learned not to take the opportunities he has had for granted. And in a press conference on Monday, he acknowledged the work of many other colleagues. “I just want to emphasize that there’s a whole field behind these studies—and, specifically within my lab, a big group of young, enthusiastic, smart scientists, of graduate students and postdocs who actually do the work.”

Erhu Cao, who was formerly a postdoctoral researcher in Julius’s lab and is now an assistant professor of biochemistry at the University of Utah, says he “was not surprised” that the U.C.S.F. researcher won a Nobel Prize for this work. “Temperature sensing is a very fundamental sense,” Cao adds. “If you cannot sense temperature, you can drink very hot coffee without noticing.” The pain response is fundamentally protective, but if it goes awry, it can cause chronic pain, he notes.

With these discoveries, and the discovery of Piezo ion channels, in particular, it's so exciting, because it gives us tools to really understand a multitude of different aspects of our physiology—everything from touch to how you control your blood pressure and sense the need to go to the bathroom, says Kara Marshall, a postdoctoral student in the Patapoutian lab and an incoming assistant professor at Baylor College of Medicine in Houston. These are things that we take for granted, because they're really important for all of these different aspects of our physiology and our sensory world, Marshall adds.

“The Nobel Prize is wonderful recognition of these discoveries,” said Scripps Research’s president and CEO Peter Schultz in a statement. “I have followed Ardem’s career closely since he first came to Scripps and can say that he is an extraordinary scientist, mentor, and colleague and a wonderful person.”