One of life's greatest mysteries has now been solved.
Georg Steinhauser, a young, affable Austrian chemist, spent three years gazing at his own navel — and those of friends and family as well — to discover how exactly we get belly-button lint.
"Abdominal hair is mainly responsible for the accumulation of navel lint," proclaims Steinhauser in the abstract to his paper, presented in the online version of the journal Medical Hypotheses. "Therefore, this is a typically male phenomenon. The abdominal hair collects fibers from cotton shirts and directs them into the navel where they are compacted to a felt-like matter."
That's in keeping with a medium-scale Australian study cited by London's Daily Telegraph, which found that the average bearer of navel lint was "a slightly overweight middle-aged male with a hairy abdomen."
We weren't willing to pay $31.50 for the full journal text, but the Telegraph was, and it came up with further nuggets: "The hair's scales act like a kind of barbed hooks. ... Abdominal hair often seems to grow in concentric circles around the navel."
Steinhauser collected a whopping 503 pieces of navel lint during his research, presumably in his spare time and on his own dime. He also noticed that "old T-shirts or dress shirts produce less navel fuzz than brand new T-shirts."
So now that we know how it forms, the next question is — why?
"Lint might ... fulfill a cleaning function for the navel," writes Steinhauser, a researcher at the Technical University of Vienna.
We eagerly hope Steinhauser next probes the question of ear hair, or perhaps the cause of waxy toe jam.