How UV Rays Made Earth Livable

Given their role in causing skin cancer, it’s understandable why UV rays have such a bad reputation. But maybe UV rays deserve a break; a team of scientists claims that they may deserve credit for making Earth a habitable environment for humans.

A Spark From the Sun

This report comes courtesy of a team of University of Colorado Boulder researchers. Billions of years ago, the earth was home to simple organic molecules living in an oxygen-poor environment. Solar ultraviolet rays might have changed this situation, facilitating the evolution of these molecules into relatively complex structures.

The team’s rationale is as follows: when the Earth had much less oxygen in its atmosphere, the Sun’s UV rays had a much easier time reaching the planet’s surface, as there was comparatively little oxygen blocking their way. While some molecules were splintered into pieces from this steady barrage of UV rays, they might have later reformed into something more advanced. “Even if you destroy a molecule, it is broken into smaller, very reactive chunks that readily undergo additional reactions, recombining to form larger high-energy molecules,” stated lead author Rebecca Rapf.

Building Something Bigger

To put their thesis to the test, the authors conducted an experiment using Pyruvic acid. While you’ve probably never heard of Pyruvic acid, rest assured that it is a very important substance in modern lifeforms. First, the University of Colorado Boulder team added some Pyruvic acid to a container of water, causing it to dissolve in a setting with limited oxygen.

With this step complete, the researchers then exposed the scattered acid molecules to ultraviolet light. In response, the acid effectively rebuilt itself, created molecules larger than what originally entered the water. The study appeared in the journal Astrobiology Magazine.

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