In 2005 Genevieve Loussouarn, PharmD, Charles El Rawadi, PhD, and Gilles Genain, PhD published an article on the Diversity of Hair Growth profiles – Or, how fast hair grows on average based on race.
Their findings across a variety of races suggest hair grows by between 250 and 400 micrometers per day. Right now, the world population is 7.4 billion. For our back-of-the-napkin calculation we’re going to ignore children under the age of one, of which there are about 150 million in the world (per census.gov). That gives us 7.25 billion people. Then we’ll estimate 1/2 of men over 50 are bald (I think this is conservative), reducing the number by 750 million or so… and voila! we have 6.5 billion full heads of growing hair! Using maths, and taking the mediaun hair growth noted by the scientists above of ~350ish micrometers per day, we can estimate that the world’s heads grow about 2,275,000 meters of hair a day or about 1,580 meters per minute. That’s 60 miles per hour of hair.
That’s a HEAD of hair. Now if we take 100,000 hair follicles per head we’ve got 6,000,000 miles of hair being produced globally per hour. If we could magically consolidate all this to a single follicle it would be launching hair out at about 1/100th the speed of light!
Recommended goal of humanity: increase population and expand to different planets/star systems until we are 740 billion in number, at which point we will collectively be manufacturing hair at the speed of light.
I got my hair cut this weekend. Needless to say, it was overdue.