The Strange Case of the Missing Sunscreen Gene

TL;DR

Vertebrates, except mammals, have the ability to produce their own sunscreen, which they acquired through horizontal gene transfer from algae around 500 million years ago.

Transcript

Thanks to Skillshare for supporting this episode of SciShow. There’s nothing more annoying than coming back after a day at the beach or a sunny vacation and noticing that there’s a perfect outline of your sunglasses on your face. You’ve got yourself a nice tomato-red sunburn, which is never pleasant. Not to mention the whole skin cancer thing. But ... Read More

Key Insights

• 🐦 Sunscreen genes are present in almost all fish, birds, amphibians, and reptiles.
• 🚥 These genes were acquired through horizontal gene transfer from algae.
• 😚 Mammals, including humans, lost the ability to produce sunscreen due to their adaptation to dark environments.
• 😎 Other sun protection strategies evolved in mammals, such as the production of melanin.
• 👨‍🔬 Research is being conducted on using genetically engineered yeast to produce sunscreen compounds in the lab.
• 🎁 Gadusol, a sunscreen compound, is already present in the marine environment and is environmentally friendly.
• 💁 Sunscreen genes could potentially be used in pill form in the future.

Questions & Answers

Q: How do organisms like fish, birds, amphibians, and reptiles protect themselves from the sun?

These organisms have the ability to produce their own sunscreen compounds, such as MAAs and gadusol, which have UV-absorbing properties.

Q: How were the sunscreen genes acquired by vertebrates?

The genes responsible for producing sunscreen compounds were acquired through horizontal gene transfer from algae, passed down for hundreds of millions of years.

Q: Why do mammals, including humans, lack the ability to produce their own sunscreen?

Mammals spent much of their evolutionary history in dark environments and did not require sunscreen. Over time, mutations occurred, leading to the loss of the sunscreen gene cluster.

Q: How do humans protect themselves from the sun without sunscreen genes?

Humans have evolved other means of sun protection, such as producing the pigment melanin, which absorbs UV light. However, this protection is limited and sunscreen is still necessary in harsh sunlight.

Summary & Key Takeaways

• Scientists have discovered that almost all fish, birds, amphibians, and reptiles possess the genes to make sunscreen compounds.

• These sunscreen compounds, known as mycosporine-like amino acids (MAAs) and gadusol, have UV-absorbing properties.

• The genes responsible for producing gadusol were acquired through horizontal gene transfer from algae, and their loss in mammals is likely due to their adaptation to dark environments.