说的是头部。狗狗权威说的下面这段。生活中倒是没见过头发胡子皆白色但是眉毛乌黑的
Body hair typically turns gray after head hair, but the order in which hair grays varies from person to person:
Nose hair: Usually the first body hair to turn gray
Head hair: Typically turns gray before body hair
Beard: Turns gray after head hair
Body hair: Turns gray after head and beard hair
Eyebrows: Turns gray after body hair
Hair graying is a gradual process that can take years. The age at which hair begins to gray is largely determined by genetics and can vary by race:
Caucasians: Typically begin to gray in their mid-thirties
Asians: Typically begin to gray in their late thirties
Africans: Typically begin to gray in their mid-forties
Some people are born with gray hair, and others may develop gray hair in their 20s or teenage years. Premature graying can be caused by a number of factors, including a lack of vitamins and minerals.