Why do fingernails grow faster than toenails?

Matthew:

Why does my fingernail grow faster than my toenail? I smashed one of each at the lumber yard last August, and the fingernail's grown back but the toenail hasn't.

-- Bob, telephonically

The science guys are pretty far behind in their toenail research, so the whys and wherefores are mostly educated guesses. Depending on who you listen to, fingernails grow two to three times faster than toenails. A fingernail replaces itself in about six months; a toenail takes a year. Feet are farthest afield in the circulatory scheme of things. A better blood supply to the fingers probably keeps them chugging along at a faster clip. Genetics plays a role too. Nails are basically protective, and since our fingers are busier than our toes, maybe they're more likely to get smashed and need replacing. There is some speculation that fingernails' constant exposure to sun and air may aid their growth. Feet are locked up in damp, dark shoes most of the time, a more encouraging environment for cultivating fungus and smells instead of nails.

If you're looking for advice, Bob, I'd suggest moving to an equatorial rain forest. Nails (toe and finger) grow faster in hot weather. Or get pregnant; that seems to speed nail growth. Men's nails grow faster than women's. The nails on your dominant hand grow faster. And the middle finger of your dominant hand is the speediest of all. I won't even speculate on why that's true.

I gather much of your time since August has been spent gawking at your feet. Actually, your days will seem to pass much more quickly if you take a comfortable chair out onto the lawn. Grass grows 50 times faster than your fingernails, double that if you've been staring at your toes.