map (function, iterable, ...) Â¶ Apply function to every item of iterable and return a list of the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel.
The grey hair ârule of thumbâ is that by the age of 50, half of the population have lost the colour in 50% of their hair. When researchers tested this rule, they found that 74% of people aged between 45 and 65 had grey hair, with an average intensity of 27%.Generally, men have more grey hair than women.he grey hair ârule of thumbâ is that by the age of 50, half of the population have lost the colour in 50% of their hair. When researchers tested this rule, they found that 74% of people aged between 45 and 65 had grey hair, with an average intensity of 27%. Generally, men have more grey hair than women.
Typical gray hair first develops at age 34.2 +/- 9.6 years in Caucasians while for Black people the average age of onset is 43.9 +/-10.3 years (Keogh 1965). As a rough guide, 50% of the population in the US and Europe have 50% gray hair by age 50.he first onset of gray hair and the speed at which people go gray varies considerably from person to person. Most people actually start going gray in their late 20s but they don't notice it immediately.