New research suggests that hair diameter increases through a person's mid-30s, compensating for the gradual loss of active hair follicles.

WSJ: Old Hair Days: Products to Help Manage Gray and Thinning Hair

That changed in the mid-1980s, when microscopic sieves--spread throughout steel tubes 30 feet long and 4 to 5 inches in diameter--were developed to filter out undesirable elements before the whey is dried to a powder for use in food manufacturing.

FORBES: Making Whey

In the mid-1980s the smallest features on chips were 1 to 2 microns wide, about one hundredth the diameter of a human hair.

FORBES: Trick Of The Light