Comets May Have Seeded Life On Earth

Did a comet seed life on earth? The theory has been floating around for years, but a fresh study in The Astrophysical Journal offers new evidence. A team of chemists from the University of California, Berkeley and the University of Hawaii, Manoa, tried to recreate the conditions found in space to see if the right chemical building blocks of life could form. Their just-published report said that they believe they have succeeded.

Deep space is cold, dark, and airless, which makes it seems like an unlikely place for the spark of life to arise. Robert Sanders at Phys.Org explained that the Hawaiian team tried to duplicate the conditions found on an “icy snowball in space” by placing the right chemicals in a vacuum chamber set at the frigid temperature of only 10 degrees above absolute zero. Then they zapped the chamber with high-energy electrons to mimic the effect of cosmic rays.

The California team analyzed the chemicals that formed as a result. According to Sanders’ report, they found “nine different amino acids and at least two dipeptides — capable of catalyzing biological evolution on earth.”

The Astrophysical Journal‘s abstract concluded:

“Once synthesized and incorporated into the ‘building material’ of solar systems, biomolecules at least as complex as dipeptides could have been delivered to habitable planets such as early Earth by meteorites and comets, thus seeding the beginning of life as we know it.

In other words, the chemical seeds can form in space on a frozen snowball like many of the comets found in orbit around our solar system. When comets get near the sun — and near our planet earth — the snowballs often melt a little, creating the distinctive long tails that we sometimes observe in our night skies.

And, apparently, they sometimes actually collide with our planet.

The next question may be just how many comets had to hammer the earth with the seeds of life before they sprouted. Michael D. Lemonick for Time reported on a theory that a “fusillade” of icy comets hit the earth far in our past, allowing our planet to become wet enough to support life. Could it be that life-forming chemicals, as well as water, were brought here by comets?

It’s nerve-wracking when huge space objects like last month’s Russian meteor slam into the earth. But we might not be here at all if not for the comets seeding life.