Biology Question #2179

Karen, a 10 year old female from Ottawa, Canada asks on July 19, 2004,

Why do your fingernails grow a lot faster than your toenails?

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The answer

Barry Shell answered on July 20, 2004

Nobody knows why. We can speculate, or make a guess, based on some observations, but this would not really answer the question. It's just a guess.

The average growth rate for nails is 0.1 mm each day, but the rate of nail growth depends on numerous factors including the age and sex of the individual and the time of year. Fingernails generally grow faster in young people, in males, and in the summer. As you have discovered, fingernails grow faster than toenails. You might not have noticed that the fingernails on the right hand of a right-handed person grow faster than those on their left hand, and vice versa. Nails on the longest fingers grow the fastest. All these facts lead one to the observation that nails that are most exposed and most used appear to grow the fastest. So while we have no direct experimental evidence to answer your question "why", we might make a guess that the reason has something to do with exposure to the elements and usage. This, however, has never been proven scientifically, so is still an open question. The correct answer is: we don't know.

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