Beard length is determined by the rate of growth vs the rate of loss. Most people reach a terminal length where these two rates are balanced and no additional length is acuired. The photos of men with extermely long beards are abnormal. The typical beard does not grow that long.
I myself have had a beard for 6 years. At about 4 years of growth, I reached a terminal length where my beard stays the same length.
'Qui non intelligit, aut taceat, aut discat'
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The industrial revolution, flipped a bitch on evolution.-NOFX
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