A Secret Superpower In Your Skin

In my previous blog post, I described the discovery of pigmented fungi that thrive in the highly radioactive environment of Chernobyl. Some scientists hypothesize that these fungi have developed an entirely new metabolic mechanism that works by capturing high-frequency photons (X-rays and gamma rays) and harnessing that energy in a way that is similar to photosynthesis. The molecule that seems to carry out this incredible function is melanin.

When I lived in Florida, I used to wonder in bewilderment why flocks of seagulls and terns would spend hours on end simply standing on the seashore, staring in the direction of the sun. They weren’t hunting, nor sleeping, nor bickering; they would simply stand there, rotating slowly to face the fiery orb, as if attending a pagan mass.

I finally found the answer to this enigma years later. Turns out, birds have a special organ called pecten, which is located inside their eyes and packed with a dark pigment melanin. It is especially prominent and deeply pigmented in long-distance migratory birds like Arctic terns. These incredible birds, who fly from the South to the North polar circle, can cover over 70,000 kilometers in a year. The extreme metabolic demands that such a journey involves have led researchers to put forth an interesting hypothesis: perhaps the pecten helps supplement the energy required.

Two Israeli researchers, Geoffrey Goodman and Dani Bercovich, proposed a concept of ‘photomelanometabolism’, whereby melanin can act as a semiconductor, converting absorbed light energy (UV and visible spectrum) into metabolic energy. Melanin inside the pecten acts as a battery, storing energy inside its complex electron lace, and releasing it when the organism is running low on fuel.

Now, I’ll start with a caveat that this hypothesis has not been rigorously investigated. But given what we know about melanin-rich fungi that seem to use X-ray and gamma radiation as a source of energy, why wouldn’t a similar mechanism be possible in birds? People have also observed that many seeds are coated with a melanin-rich outer layer and suggested that melanin in the skins of seeds and pits (like chestnut, avocado or black cumin) allows them to germinate when they come in contact with water. The water acts as an electrolyte for the melanin battery, allowing the electrons stored in melanin’s complex chemical structure to activate the energy transduction circuits and jump-start the dormant mitochondria for ATP production.

Melanin in human skin

We typically think of melanin as simply a built-in sunscreen that protects the DNA in the deeper layers of our skin from UV damage. But the melanin story is a lot more intricate. For example, did you know that melanin is present in internal organs and tissues like the inner ear, heart, fat cells, meninges (the protective membranes around the brain and spinal cord), and inside our brain? If it were simply a ‘sunscreen’, why put it where the sun don’t shine?

Perhaps the answer lies in the different types and functions of melanin. There are three types of this pigment in humans: eumelanin and pheomelanin, which are found in the skin, hair, and iris of the eye, giving them distinctive color, along with neuromelanin, a special type of pigment found in certain regions of the brain. Eumelanin has a dark brown to black color and works remarkably well at absorbing UV rays and dissipating that strong energy as harmless heat. Pheomelanin, on the other hand, is yellow or red and is present in people with lighter skin tones. It contains sulfur atoms in its structure and, while it also absorbs UV photons, it does so less efficiently and produces reactive oxygen species (ROS), which can actually damage skin cells.

Neuromelanin has an entirely different function. The highest concentration of neuromelanin is found in the substantia nigra, a brain structure responsible for dopamine production and involved in motor control, reward, and cognitive processes. In diseases such as Parkinson’s, neuromelanin is lost, highlighting its importance for brain function. One of the reasons for this may be that neuromelanin (like all other melanin types) plays an important role in sequestering free radicals and binding heavy metals that would otherwise damage cells. Or could it also provide that extra ‘oomph’ for energy-intensive brain activities?

Systemic effects of melanin

Melanin in the skin is produced in response to UV damage. When we sunbathe, the regions of the skin exposed to UV rays will start producing melanin as a protective mechanism. But melanin production is also systemic. As any dermatologist will tell you, getting sun on any part of your body will stimulate pigmentation in other places that had not been exposed. For example, you may cover your face with sunscreen and wear a hat, but if you tan the rest of your body, you might still get freckles or sunspots on your face.

By extension, if sun exposure can activate melanocytes in the regions of the skin that did not receive direct UV, it could also activate melanization of internal organs, including vital tissues and organs such as the heart and brain. Moreover, sunlight on the skin triggers the body to transcribe a gene called proopiomelanocortin (POMC), which is then cut into three essential peptides: adrenocorticotropic hormone, melanocyte-stimulating hormone (MSH), and beta-endorphin. The first one regulates stress and metabolism, the second one stimulates melanin production, and the third one makes you happy. (Could that be the reason why people come back from beach vacations thinner, darker, and happier?1)

One thing that is known for sure is that melanin is a powerful antioxidant and a free radical scavenger, stronger than many of the well-known commercial analogues, including vitamin C or carnosine. It also works better at binding metal ions than the well-known chelator EDTA. In fact, melanin-packed fungal nanoparticles are being used to clear heavy metals (copper, lead, cadmium, nickel, and chromium) out of groundwater. A similar detoxification mechanism may work in humans: melanin in the skin, the body’s largest organ, could trap heavy metals and get rid of them as the dead skin cells slough off.

An interesting correlation between sun exposure and the abundance of melanin also exists in Parkinson’s disease. It’s been shown that people who get less sun are more susceptible to developing the debilitating neurodegenerative condition, which is characterized by the loss of melanin from the substantia nigra. Now, it is possible that the reason for the progression of the disease is low vitamin D levels in individuals who don’t get sufficient sun exposure, since vitamin D plays a big role in neuroprotection. But the presence (and loss) of neuromelanin in the brain indicates that the sun’s neurological benefits likely go beyond vitamin D.

A built-in superpower

Am I trying to say that increased production of melanin confers biological advantages?? If you look at the animal kingdom, melanized animals are often stronger, more resistant to disease, or better adapted to harsh environments. For example, black leopards and servals are not only better hunters, but they are also more resistant to viral infections. Black lizards have a stronger bite force than non-melanized counterparts. In insects, melanin is crucial for wound healing.

We all have this superpower, and we don’t even realize it. Melanin acts as a signal transduction molecule, translating light cues into the language of chemical signals that biology speaks. Besides being a built-in sunscreen, it is also a powerful free radical scavenger, antioxidant, and heavy metal absorber that protects our cells, from the surface of the skin to the depth of the brain. And it could even act as an ‘emergency power source’, providing redox potential for tissues in critical need. What allows it to serve so many different biological purposes is its ability to capture photonic energy in its intricate chemical structure—a fundamental physics layer that gives a theoretical basis to all the wild claims about melanin.

To think that historically (and to this day) people opted out of melanin activation for whiter skin, not understanding the incredible benefits it provides! To me, this is just another confirmation that everything we do in our society is backwards: we value aesthetics over health, put prejudice over function, and would rather pay for expensive cures than trust in a free, built-in mechanism that has been perfected by biology over millions of years.