Can Science Tell a Gymnast's Age?

As much a fairy tale as the gymnastics competition has been for China, with the country snagging men's and women's team event golds and 14 of the 42 medals awarded in the sport in Beijing, the story may not have such a happy ending. Allegations that at least five of the six women's team members are younger than the International Olympic Committee (IOC) minimum age of 16 continue to fester, as documents with later birthdates for some of the girls have surfaced.

The lingering questions highlight one of the few areas in sports science today that remains untestable. Researchers can screen for illegal substances, determine your gender, and tell you whether you're fighting a cold, all from a few blood and tissue samples. But they still cannot definitively determine a person's age. The existing tests can come close, probably to within two years, but that's the best that current methods can do. And two years is exactly the age gap in question with the Chinese female gymnasts.

Under pressure to address "age-doping," the IOC asked the International Federation of Gymnastics (FIG) on Friday to re-open the Federation's previous investigation into the matter of the girls' ages. Prior to the competition, when rumors of the under-aged gymnasts first surfaced, the FIG had looked at the passports of the gymnasts and declared itself satisfied that the girls were at the lower-age limit of 16, not 14, as some earlier news reports on the girls had noted. Now, the FIG is asking the Chinese Gymnastics Association for further proof of the athletes' ages. The United States Olympic Committee also sent a letter to the IOC on Friday asking that the issue be resolved. The U.S. women finished second to Chinese in the team event on August 13. "USA Gymnastics has always believed this issue needed to be addressed by the FIG and IOC," said Steve Penny, president of USA Gymnastics in a statement. "An investigation would help bring closure to the issue and remove any cloud of speculation from this competition."

But will it? At the moment, the only proof that IOC and FIG officials can rely on will be registration documents from previous competitions, or birth records of the girls' that would show different birth dates. Biologically, says Dr. David Sinclair, a pathologist at Harvard Medical School who studies the aging process in animal models and people, "There are many possible methods to determine age, but they are not very accurate. The error is about two years." Most of these are also based on forensic approaches and have not used to screen for age in living people. In some cases, current imaging techniques simply cannot provide the level of detailed information required to make the methods practical for situations such as the one facing FIG.

Still, there are ways to using modern imaging technology to potentially glean more scientific information on the gymnasts' ages. Dental records are commonly used to determine age, since the wearing down of teeth correlates with how long a person has been living — and eating — but, again, only within a two year window.

Another strategy, which is still experimental, unfortunately works best in male athletes. MRI of the wrist bones and the extent to which they have fused has been used to screen out boys too young to play football. The older the player, the more fused the bones should be. These structures, however, don't fuse the same way in girls, making this test gender-specific.

Other bones can provide additional clues. Elbow bones tend to fuse in a chronological order, so scans revealing how far along this process has come could provide more information about age. The skull can also be helpful. Babies are born with an unfused cranium and, as children grow up, a series of sutures come together to seal the gap. In some, however, certain sutures remain open through adulthood, making this an important but hardly conclusive test.

The rib bones are another resource — in young children, the tips of the ribs that connect with cartilage are relatively flat, but as a person ages, says Sinclair, "these endpoints become ragged and the cartilage is pitted." It is not clear, however, how easily this wear-and-tear can be detected and, if it can, whether the ribs of a 14-year old would appear much different from those of a 16-year old.

On the more molecular side, newer genetic and biochemical tests for age are not proving as robust as scientists had hoped. The most exciting method, in which researchers measure the length of telomeres, or the string of DNA at the ends of chromosomes, has proven too unreliable. Just a few years ago, genetic experts had thought that aging cells had shorter telomeres, but it turns out that these bits of DNA can get snipped off even in relatively young cells. "We all age at different rates at the molecular level," says Sinclair.

For scientists, the best method for narrowing down a person's age is a combination of five weighted factors known as the Complex Method. It includes analysis of the pubic bones that lie just under the navel along with some vertebral bones, both sets of which start out rough in youngsters but smooth out over time; images of the femur, or thigh bone, which becomes thinner and loses bone mineral over time; dental wear; and closure of the cranium. However, it's unlikely that IOC or FIG officials will go so far as to impose these types of biological tests on the Chinese gymnasts — especially since none of these methods can definitively pinpoint any of their ages as either 14 or 16.

The parents of the girls are outraged that their children's ages and abilities are under suspicion. However, the reasoning behind the IOC's age minimum was to protect the athletes. Gymnastics in particular has a new code of points that rewards the most difficult routines and, as a result, training sessions in the sport have have only become more grueling. Keeping the youngest competitors from the rigorous world of international competition is supposed to protect them from dangerous, potentially life-long injuries. In that respect, age doping is no different from other illegal performance enhancing tactic — not only is it unfair to the rest of the competitors, it's most unfair to the athletes doing it to themselves.