By the time you reach 13,000 or so, you'd figure that the people closest to you would know some fundamental personal details -- like your sex.
But consider the plight of the oldest person yet found in North America.
All that remains of him -- or is it her? -- are a couple of thigh bones, which were discovered on Santa Rosa Island in 1959. At the time, scientists thought they belonged to a man of a certain age -- perhaps 10,000.
The bones of the person they named Arlington Springs Man were stored away at the Santa Barbara Museum of Natural History, only to be reexamined with new techniques four decades later.
Seen in a new light, the age of the bones soared by 3,000 years. And -- oh, yes -- Arlington Springs Man, it seemed, really was Arlington Springs Woman.
The new name stuck until last week -- when Arlington Springs Woman again became Arlington Springs Man.
"Yes, we've had a gender change here," John Johnson, the museum's director of anthropology ruefully acknowledged, anticipating a barrage of bad one-liners on late-night TV.
"When we said she was a woman, Jay Leno told jokes about it," he recalled. "Something to the effect of, 'Here's another woman lying about her age -- she said she wasn't a day over 10,000.' "
The latest rethinking of the Arlington Springs Person's sex started when Johnson showed one of the partially intact femurs to a visiting anthropologist. The researcher was dubious, insisting that she was viewing the leg bone of a man.
Measurements were taken and retaken. Other ancient bones were used for comparison. Johnson delved into the notes of the late Phil C. Orr, the anthropologist who made the find.
It turned out that Orr had recorded the diameter of the femur's head, which is now missing -- and which was rather large, in a masculine kind of way.
That has tentatively -- but not conclusively -- persuaded Phillip Walker, the UC Santa Barbara anthropologist who initially made the female designation, to reverse himself.
"It's a question of probabilities," Walker said. "That's the way science works."