JOE TUCCIARRONE/SCIENCE PHOTO LIBRARYCORBIS
The crash of meteors on early Earth likely generated hydrogen cyanide, which could have kick-started the production of biomolecules needed to make the first cells.
Science has a story about the origin of life on earth. "How did life arise?" It's long been a question that has baffled both modern day scientists and our ancient brethren. Now, we may have a few more pieces of the puzzle. Some chemists from the University of Cambridge in the United Kingdom have reported that they have created nucleic acid precursors starting with just hydrogen cyanide (HCN), hydrogen sulfide (H2S), and ultraviolet light.
Sutherland’s team argues that early Earth was a favorable setting for those reactions. HCN is abundant in comets, which rained down steadily for nearly the first several hundred million years of Earth’s history. The impacts would also have produced enough energy to synthesize HCN from hydrogen, carbon, and nitrogen. Likewise, Sutherland says, H2S was thought to have been common on early Earth, as was the UV radiation that could drive the reactions and metal-containing minerals that could have catalyzed them.
That said, Sutherland cautions that the reactions that would have made each of the sets of building blocks are different enough from one another—requiring different metal catalysts, for example—that they likely would not have all occurred in the same location. Rather, he says, slight variations in chemistry and energy could have favored the creation of one set of building blocks over another, such as amino acids or lipids, in different places. “Rainwater would then wash these compounds into a common pool,” says Dave Deamer, an origin-of-life researcher at the University of California, Santa Cruz, who wasn’t affiliated with the research.
