Question 2

Why does the sun make our hair lighter but make our skin darker?

ChatGPT

The sun has different effects on hair and skin due to the distinct biological processes involved in each case:

Skin Darkening (Tanning):

• Melanin Production: When skin is exposed to ultraviolet (UV) radiation from the sun, it stimulates the production of melanin, the pigment responsible for skin color. Melanin absorbs and disperses UV radiation, protecting the skin from damage. The increased production of melanin leads to a darker skin tone, a process known as tanning.

• Protective Response: This tanning response is a natural protective mechanism. Melanin helps to shield skin cells from DNA damage caused by UV rays, reducing the risk of skin cancer.

Hair Lightening:

• Lack of Melanin Production: Unlike skin, hair is made up of dead cells once it grows out from the scalp, meaning it doesn't have active cellular processes. Hair doesn't produce new melanin in response to sun exposure.

• Photobleaching: UV radiation from the sun breaks down the melanin in hair. This degradation of melanin results in a loss of color, making hair appear lighter. This process is similar to how the sun can bleach other materials, such as fabrics or paper.

• Cumulative Effect: Over time, repeated exposure to sunlight can lead to significant lightening of hair, especially in individuals with lighter hair colors to begin with.

In summary, the sun darkens skin by stimulating melanin production as a protective response, while it lightens hair by breaking down existing melanin without any compensatory production.