Dracula sank his fangs into people’s necks looking for it. Greek gods got it from ambrosia. Spanish conquistador Juan Ponce de Leon set out to find it and discovered Florida instead, or so legend tells us.

Now, a former Washingtonian who heads a California venture fund has enlisted nearly a dozen teams of scientists in a 21st-century hunt for the fountain of youth. And he has set a $1 million cash prize for the winners.

Joon Yun, a radiologist who heads Palo Alto Investors, has created the Palo Alto Longevity Prize as a way to urge researchers to “hack the aging code.”

“The way we are innovating in health care addresses the consequences of aging, but we’re not addressing the root cause,” Yun said in a telephone interview Monday. “So as a result of that, we ultimately can’t save people. So people ultimately age, they age out, and they die.”

Finding a solution to aging that would prolong lives and maintain their quality, he said, “remains one of the grand challenges for our society.”

Yun’s hope for unlocking the key to aging lies in finding ways to restore the body’s balance when it comes to its internal response to stress or calm — a process known as homeostatic capacity. In the daily grind of life, the nervous system’s balance tends to veer toward the stress response as people age, and its side effects — including inflammation and elevated heart rate — take a toll on the body.

“The idea here is to help restore homeostatic capacity. Part of the aging process appears to be the loss of homeostatic capacity,” Yun said.

The venture comes as the populations of the United States and other developed nations are growing older. One in five Americans will be 65 years or older by 2030, according to the Census Bureau.

Among the scientists who have accepted the challenge is David Mendelowitz, vice chairman of George Washington University’s Department of Pharmacology and Physiology. Others include a team from Charité University School of Medicine in Berlin, which will focus on gene modification; a group from Albert Einstein College of Medicine in New York, which will look at hypothalamic regulation; and a team from the Texas Heart Institute in Houston that will examine the role of stem cells in aging.

“We believe that aging is both a failure of stem cell number and stem cell function,” Doris Taylor, who heads the Texas Heart Institute’s group, said in an online video. “It’s really not that complicated: replace stem cell number, replace stem cell function, prolong life.”

The competition will begin Tuesday at an event at the Golden Gate Club in San Francisco. The prize will be split into two $500,000 awards. The first — to be awarded on June 15, 2016 — will go to whatever group can demonstrate the ability to restore homeostatic capacity in a test animal, as reflected in heart rate variability. That might mean showing that an aging mouse has the healthy heart rate of one much younger.

The second $500,000 prize will be given to the team that can show it has increased an animal’s longevity by at least 50 percent, also by enhancing its homeostatic capacity. Teams have until Dec. 1, 2015, to sign up.

“We think it’s a laudable goal,” Mendelowitz said. In a video and an interview, he said he welcomes the opportunity to compete because the prize’s aim is closely linked to his research. His work focuses on the autonomic nervous system, which is the part of the brain that involuntarily controls vital functions such heartbeat, breathing and digestion.

Under stress, one part of the autonomic nervous system, known as the sympathetic nervous system, reacts by increasing the heart rate, releasing adrenaline and preparing a person for “fight or flight.” The parasympathetic nervous system does the opposite — maintaining calm that protects the body, particularly the heart, Mendelowitz said.

“If we’re running away from a tiger, we obviously want to increase our heart rate and be bigger, stronger and faster. The sympathetic system is great at that,” Mendelowitz said. “The parasympathetic system is better activated when you’re reading a book in the library. You’re calm. . . . You have a really low heart rate.’’

He said that over time, the balance between sympathetic and parasympathetic “gets pushed to the sympathetic side.”

His lab is looking for ways to enhance the parasympathetic nervous system.

“That’s certainly our goal, and I think we have some results that lead us to be excited about that,” Mendelowitz said.

Yun, 46, grew up in Rockville and attended the private St. Albans School before going on to Harvard, Duke Medical School and Stanford. He has co-written two books that theorize that the food we eat contains stress that is transmitted to our bodies.

In “Low-Stress Food,” Yun argues that modern food production methods create stress hormones in plants and animals that are passed on to people. Instead of relying on factory-farmed animals, for example, he urged consumers to eat free-range animals.

“There’s no data for this,” Yun said. “But this is an intuition that this is an area we should be studying.”

Palo Alto Investors has more than $1 billion in assets, he said. Yun, who joined the hedge fund about 15 years ago, is a health-care specialist for the firm and “an early investor in companies that develop drugs and devices for unmet medical needs,” his Web site says.

“In a way, people have been interested in aging for a long time,” Yun said. “This [prize] is a very specific initiative intended to nurture specific innovations that can help us crack the aging code.”