Why Don’t Birds Need Sunscreen?

For a sandpiper at the beach, forgetting the sunscreen is no big deal. In a paper published in eLife, researchers found that birds, along with fish, reptiles, and amphibians, are capable of producing a chemical called gadusol, which shields them against cancer-causing ultraviolet radiation.

It was previously known that various bacteria, algae, and marine invertebrates manufacture gadusol-like compounds to deal with constant sun exposure out on the open water. The same compounds were also found in fish. Scientists believed that fish acquired gadusol by eating those smaller organisms, or through some kind of symbiotic relationship.

“No one realized that fish themselves actually produce the compounds,” says lead author Taifo Mahmud, a professor at Oregon State University’s College of Pharmacy.

That is until Mahmud and his team identified a gene in vertebrates extremely similar to the one in algae. They then took that gene from a zebrafish, placed it in E. coli, and found that gadusol was expressed when the gene was combined with another protein.

The researchers also checked the genomes of birds, reptiles, and amphibians and found that they contain the same gene, which means that other animals should be able to produce their own sunscreen, too. Mammals, on the other hand, lost the gene millions of years ago, and it’s still unclear why.

At first, Mahmud thought it might have something to do with the fact that birds, reptiles, amphibians, and fish all lay eggs. But that theory took a hit when he failed to locate the gadusol gene in the platypus, one of only two mammals that lay eggs. 

In addition to providing protection against the sun, gadusol is considered an antioxidant. Mahmud says it’s used as an ingredient in a small number of anti-aging creams and other health products, and that more such products may be on the way now that the researchers have figured out how to produce gadusol in high volumes. The trick is to express the gene in  yeast cells and extract it that way. 

But before ditching the SPF for a gadusol pill, remember that it’s still unknown whether the chemical can be effectively absorbed by the human body. Though it's probably safer than drinkable sunscreen, to say the least.