Blue Sky Science: Why do we have freckles?

Molly Torinus


Why do we have freckles?

Freckles are composed of an ingredient called melanin, which protects against damage caused by UV light. Your body makes melanin to protect itself from sun damage.

When people who have darker skin make melanin, it often looks like a sun tan and is more evenly distributed. In people who have very light skin, melanin is produced as these finely clumped granules that look like freckles.

The way your body produces melanin – and whether you get freckles—is determined by your genetics. Over time freckles are a sign of having had sun exposure. Because your body is trying to make melanin to protect itself from sun damage, the more sun exposure you get, the more freckles can appear.

Melanin is produced along a pathway that starts with tyrosine, an amino acid also known as one of the protein building blocks of life. Tyrosine is converted in a series of steps into one of two types of melanin: eumelanin or pheomelanin.

Eumelanin is associated with darker skin, hair and eyes, while pheomelanin is common in those with lighter skin and red or blond hair. Both types of melanin have the same purpose of protecting your body from the sun’s UV rays.

The adage says that 80 percent of the sun exposure people attain over their lifetime happens in the first 18 years. Childhood is the biggest risk for sun exposure, which is why early prevention measures are important for both near-term and long-term health.