When it comes to trekking up Earth's tallest peak, age matters.

New research reveals 60-year-olds lag behind 40-year-olds in reaching Mount Everest's summit. And for those who make it, the 60-and-overs are more likely to die on the descent.

"On Everest, youth and vigor trump age and experience," the study authors say.

Compared with decades ago, Mount Everest has become an adventure-vacation hotspot with a reported 600 people reaching the summit this spring. Climber age also has skyrocketed since 1953 when the first two climbers to scale Everest, Edmund Hillary and Tenzing Norgay, aged 33 and 39 at the time, respectively, summited.

In recent years, nearly half of all Everest climbers are at least 40, and one out of every 30 is at least 60 years old, scientists say. Greater physical health as well as the accessibility of guided expeditions could explain the hike in climbing age.

How age affects climbing success, however, has been an unknown.

"Younger climbers have a physical advantage but probably have less experience than older climbers," said lead author Raymond Huey, a biologist at the University of Washington. "We used to refer to this advantage of age as the Kareem Abdul-Jabbar effect. As he got older, his physical skills declined but he was so smart and experienced that he was able to compensate and still play professional basketball at the highest levels."

The new study, published in the Aug. 15 issue of the journal Biology Letters, shows "that effect does not apply on the world's highest mountain," Huey said.

Huey and his colleagues ran statistical analyses on the success and death rates of 2,211 climbers who attempted Everest during the spring seasons from 1990 through 2005. A bulk of the information came from journalist Elizabeth Hawley, who chronicled climbing expeditions in the Himalayas.

While the analysis revealed no gender differences, age differences were stark. Overall, the climbers had a 31 percent chance of reaching Everest's summit. The success rate dropped to 13 percent for climbers in their 60s. The 60-and-overs also had a 5 percent chance of dying on the mountain—more than three times the overall death rate for the climbers.

The scientists suggest climbers older than 40 have reduced physical capabilities compared with their younger counterparts and might also have a higher degree of caution that causes them to stop short of Everest's pinnacle.

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