Airdate: Dec 19, 2000
Scientist: Lynn Rothschild
Astrobiology - UV Rays
The sun's ultraviolet radiation can be harmful, but it's been an important force in the evolution of life on Earth.
We've all heard that the suns ultraviolet rays can be harmful. But scientists tell us that ultraviolet radiation has also played an important role in the evolution of life of earth. I'm Jim Metzner and this is the Pulse of the Planet, presented by DuPont. Lynn Rothschild is an astrobiologist with NASA -- a scientist who studies life in the universe.
"I personally believe that UV rays have had quite an important influence on the evolution of life. UV can damage DNA. UV damages almost every system that's ever been looked at. Any organism that is going to evolve or survive any length of time is going to have to somehow deal with this issue of having UV rays out there. The very oldest sorts of organisms that we see on Earth today all have some mechanisms to protect themselves by producing sunscreen pigments like melanin. In other words, tanning. Organisms can also hide from the UV. You could go under a rock. You can go into sand. You could go under a tree. You could go into your house."
But Lynn Rothschild says it's the tiniest things on earth -- the microscopic organisms such as bacteria and certain algae -- which can teach us the most about ultraviolet radiation.
"Microbes evolved at a time that UV flux was much higher on the surface of the Earth. Several billion years ago there was no ozone shield. So these organisms were exposed to extremely high levels of UV radiation during their early evolution. By looking at the microbes the way I do, we have some idea of how organisms survive on Earth today, how they may survive in outer space, how an organism on Mars might have evolved, or how it could survive there today."
Pulse of the Planet is presented by DuPont, bringing you the miracles of science, with additional support provided by the National Science Foundation. I'm Jim Metzner.