L'Oreals research blames excess Collagen for baldness.......

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The average life expectancy of drug-addicted homeless man is something like 48 years old. It's not that they have great hair, it's that they are much younger than you think. Their faces & bodies look prematurely aged but their hair does not.

 

[coolio]

Only men with significant baldness show a visible high Norwood that early. The average man in his 40s might have a low-Norwood hairline recession. The rest of his head will have some subtle miniaturization in a higher Norwood pattern but it's probably not obvious enough to make him "the bald guy" for a while yet.

The average goes by the decade. About 20% of men are showing hair loss in their 20s. About 30% of men are showing by their 30s. Etc. Caucasian men & western men have it a bit worse these days but the formula is not too far off.

Homeless men get hair loss too. They just don't live long enough for it to be as obvious as in the general population.