The onset of hair greying in humans varies from person to person, as well as among racial groups of people based on genetic and other germane factors.
It has been established empirically that white people start to grey in their mid-or late 30s whereas African Americans begin to grey in their mid-40s. Averagely, however, most people grow grey hair in their late 30s or mid-40s.
Hair research suggests that after age 30, there is about a 10 per cent decrease in melanin levels. By age 50, half of men and women tend to have at least 50 per cent grey hair.
However, people can get grey hair at any age, even as early as their basic school years. In view of the age influence of grey hair, most people start having grey hair around the same age their parents or grandparents first had it. It takes more than 10 years for all of a person’s hair to turn grey.
Whereas it is globally believed that grey hair is a harbinger of old age, others also believe from religious and social perspectives that grey hair is a sign of wisdom.
Do wise people have grey hair? Is every person with grey hair a wise person? These questions constitute the impetus for this piece.
Ageing and hair colour
It is a trite occurrence worldwide that hair colour changes as people age. Hair greying is thus a hallmark of aging and it affects almost everyone but exceptions abound.
Scientifically, the loss of hair colour is due to the loss of melanin, a pigment found in the skin, eyes and hair.
Melanin and genetic codes give colour to the hair. As people grow older, pigment cells in their hair follicles (tubes of tissue under the skin) gradually die, leading to a more transparent colour (grey, silver or white).
Apart from ageing, other factors such as limited vitamin B12 deficiency, stress, thyroid disease, vitiligo and smoking lead to hair greying.
The claim that stress leads to hair greying has been debated over the years without much evidence. However, a new study shows that stress leads to premature hair greying by affecting the stem cells that regenerate hair pigment.
Religion
Religiously, people believe that a person with grey hair personifies wisdom. The three Abrahamic religions, such as Judaism, Christianity and Islam, have certain recognition for grey-haired individuals.
Both science and religion agree that grey hair is a sign of ageing. However, science does not say that ageing necessarily connotes wisdom but religion shows that grey signifies wisdom.
In Judaism and Christianity, God commanded such demonstrations of respect for grey hair in the laws He gave to ancient Israel.
