Sunday, June 20, 2010

Why does human hair grow indefinatley? while animal hair does not?

does human hair stop growing? are there examples of animal hair growing indefinatley? how come like cat and dog hair stops growing?



Why does human hair grow indefinatley? while animal hair does not?

"The bottom line is that hair doesn't grow forever. It grows as long as the hair follicle is in active growth. How long a particular hair follicle is in active growth depends upon various factors. It could be genetically programmed to be in active growth for years, or only for weeks. Most dog breeds have a coat that is genetically programmed for a shorter growth cycle than those similar to the poodle coat. The coats of dogs with a long hair growth cycle will shed less. "



http://www.dogplay.com/Articles/MyArticl...



Why does human hair grow indefinatley? while animal hair does not?

some hairs on your body are programmed to stop growing like on your arms and legs, I think it's only your head and facial hair that continues to grow. however Ive just raised a new question haven't I?



Why does human hair grow indefinatley? while animal hair does not?

Human (head) hair doesn't grow indefinitely - but it might grow quite long.



It's a question of how long the root continues to produce hair before shedding the hair and renewing. Different hair follicles in different animals "live" for different lengths of time, and this dictates the hair length. In fact, different follicles in different locations on one organism can live for different lengths - pubic hair doesn't grow as long as head hair, nor do your eyebrows or eyelashes.



Evolutionarily, coat length will be an important feature: you don't want to get cold, but you also don't want to get tangled in bushes. So a "middle" length will be selected for.



Why human head hair continues to grow, I don't know.

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