Appliance of Science: How and why do we get freckles?

This question was sent in by seven year old Daniel; he would like to know… how and why do we get freckles?

Freckles are fairly common, especially in people with fair
complexions but people with darker complexions can get them too.
Before we look at how and why they appear, we need to first consider what they are?

WHAT ARE FECKLES?

Freckles are small spots on the skin, they are usually tan or light brown in colour. Unlike moles or some birth marks, freckles are flat on our skin. Freckles are completely natural and harmless.

We are used to seeing them on peoples’ faces but they can be found all over the body. Although it is rare, some people even have freckles on the palm of their hand or sole of their foot.

Freckles often become more obvious or more abundant when we expose our skin to the sun and that gives us the first clue as to why they appear. Most freckles disappear after a while, particularly when our skin is not exposed to as much sunlight.

NATURAL SUN SCREEN

Freckles are the result of a natural colour (or pigment) called melanin produced by the body to protect the skin against the harmful rays of the sun.

This process is called photoprotection and this is how it works… When UV rays of light from the sun hit our skin they trigger certain cells in our body to make more melanin. The cells that make the melanin are called melanocytes. The melanin is sent to the outer layer of our skin where it absorbs these harmful UV rays, protecting the skin cells (and the cells’ DNA) from their damage.

Usually melanin is distributed evenly around the parts of the skin that are exposed to the sun, causing our skin to tan. Sometimes though, the melanin clumps together in small areas, forming little dark spots that we call freckles.

Freckles can also be due to small areas of skin where the melanocytes produce too much melanin.

We have a lot less melanocytes in the skin of our palms and the soles of our feet, which is why we don’t tan in these areas. It is also why freckles are rare on these parts of our body.

CAN ANYONE GET FRECKLES?

Freckles are certainly very common among people with fair complexions. They also tend to be more noticeable on fair skinned people, but people with all types of skin tones can get them. Freckles tend to run in families, so if your parents have them there is a good chance you do too. The tendency to get freckles is linked to a gene called MC1R.

WHEN IS A FRECKLE NOT A FRECKLE?

Moles and birthmarks tend to be darker than freckles and may also be slightly raised.

Dermatosis papulosa nigra (DPN) is common among darker skinned people although all skin tones can have these spots; they appears as dark spots on the skin, often on the face.

Although they look very like freckles, or moles, they are actually different, although they are also harmless. Lentigines are tan spots on the skin that often appear later in life. Freckles frequently decline as we age.

Naomi Lavelle is a science communicator and mother to three inquisitive children. She can be found at sciencewows.ie. Email your questions to drhowsciencewows@gmail.com.


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