Health & Medicine / Aging

When Justin Congdon was a teenager, he spent his days in the woods of northeastern Pennsylvania, shooting pheasants and trapping muskrats so he could sell their pelts for $4 apiece. He would have laughed had anyone told him he might spend the rest of his life in a forest preserve trapping turtles, X-raying their bellies, and painstakingly gluing their shells back together when they had the bad luck to be hit by cars.

But that's precisely what he's doing on this late May afternoon at the University of Michigan's E. S. George Reserve, as he has done every spring and summer for 27 years. Carrying a leather tool belt with a makeshift rectal thermometer, needle-nose pliers, and black Sharpie pen, he patrols East Marsh, an 11.5-acre habitat with water lilies and wild irises. Most of the time he's on the lookout for female turtles— Blanding's, Common Snapping, and Midland Painted— abundant with fertilized eggs and ready to unload them on the first warm day. A low plastic fence separates the turtles' marshland habitat from the higher, drier ground where they build their nests. For 16 hours Congdon circles the marsh, following the fence that keeps the turtles from escaping. Any gravid— pregnant— female that wants to leave the marsh must make a small contribution to science before she's permitted to seek out a place to lay her eggs on the other side of the fence.

He spots a Midland Painted searching for a way past the barrier. She has the characteristic bright red trim around the edges of her shell and the intricate lined pattern, almost like a cave drawing, underneath. He picks her up and pops his thermometer in her cloaca, the chamber in her tail where the digestive, urinary, and reproductive organs come together. She flails her legs wildly and voids water onto Congdon's hands, but he gets his reading, a useful piece of information for understanding how the turtle manages the heat it needs to carry out reproduction and other biological functions. With the Sharpie, he marks her underside, or plastron, with body temperature, time, and location, tosses her into a camouflage-colored bag, and strides quickly back to his turtle-processing shed, a former military radar outpost that has become the border patrol for wandering reptiles.

In this primitive two-room shed, Congdon has conducted some of the most sophisticated life-history studies of long-lived vertebrates— research that could upend our theories about how animals grow old and might one day help unlock secrets of human longevity. For 49 years scientists have cataloged more than 12,000 turtles living on the reserve, compiling a huge database of individual reptiles. Each new capture has its shell marked for identification, and all animals are weighed, measured, and inspected for disease or injury. Gravid females are X-rayed to determine how many eggs they're carrying and how big they are. Nests are tracked and locations recorded. During peak season, the shed sometimes looks like a turtle traffic jam, and processing can take until 2 a.m.

Today's catch is a 16-year-old female that has been caught and X-rayed five times since she first reproduced in 1996. Some of the turtles that show up at the shed are much older; although tagged as adults in the 1950s, they are still healthy and fertile. They're also the key to Congdon's groundbreaking discovery: Blanding's and perhaps also Midland Painted turtles don't senesce— deteriorate physically— as they grow old. They simply don't age. And Congdon says the females actually produce more eggs as they grow older: "They're crankin' compared to the young ones." When they do die, the cause is often an attack— hit by a car or mauled by a raccoon— or one of a number of infectious diseases that kill these turtles at all ages in seemingly equal proportions. While certain ailments, such as cancer and heart disease, strike older humans more often than they do younger ones, Congdon's animals don't seem to become more vulnerable to disease as they grow older.

The findings are turning the discussion of aging in mammals upside down. "His work is a sharp challenge to a theory that has been taken at face value— that senescence is inevitable," says Caleb Finch, professor of biological sciences and gerontology at the University of Southern California. "Here you have a vertebrate turtle that shows no increase in mortality and no loss of reproductive capacity at ages where mammals, including humans, will shut down totally." Other species with long life spans include sharks, tarantulas, and rockfish, and human gerontologists are starting to pay close attention. As Huber Warner, associate director of the Biology of Aging Program at the National Institute of Aging, says, "If we knew what regulates life span in turtles, that might be useful in figuring out how humans age and how to intervene."

The first thing you notice about Justin Congdon, other than his deeply creased face and wild gray beard, is his passion for telling one bravado-tinged story after another, preferably over a cold Budweiser. Sit long enough and you'll hear about his adventure on a runaway logging truck while collecting lizard blood in the jungles of Mexico, an accident in which he almost lost a hand. Or he'll tell you about his run-in with a particularly testy Banded Water Snake that he spotted one evening while walking along the fence at the Michigan reserve. The snake had been tagged by a graduate student, but "I hadn't brought a flashlight. So I grabbed the snake and flipped its head back and pulled the tail up to read the ID. I didn't see, because it was getting dark, that the snake had pulled its head free, and it bit me in a wide-open eye."

The impression he creates is that of someone who lives far more happily outside polite society, someone who is simultaneously a meticulous biologist and a swashbuckling cowboy. Both images of himself seem to grow from the same impulse— the desire to dwell in unfettered wilderness, in places where people don't sip champagne. "A few years back, Gianni Versace was killed in Florida," says Mike Plummer, a biologist at Harding University in Searcy, Arkansas, who was eating dinner with Congdon the night the fashion designer was murdered. "Somebody came out on the news and said, 'Tonight the world mourns for Versace.' Justin said, 'Can you believe that? The world mourns for the death of a guy who sews pants?'"