The effect of aging on the rate of linear nail growth.
The linear nail growth rate is a simple, inexpensive, noninvasive technique for the measurement of aging. When the many endogenous and exogenous factors known to influence this rate are either controlled or considered, the measurement of the rate for 1 year gives data that are both age-related and age-caused. The rate of linear nail growth decreases 50% over the life spans of both dogs and humans. In the beagle, which has a life span 20% that of man, the rate of decrease is 5 times faster than in man. There are circadian and multiple-year biorhythms of the rate of linear nail growth. There are approximately 7-yr periods of slow decline that alternate with 7-yr periods of more rapid decline.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D000818:Animals; D002648:Child; D002940:Circadian Rhythm; D004285:Dogs; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009262:Nails / Q000254:growth & development*; D012881:Skin Temperature