Researchers from Harvard, MIT, and the University of Cambridge have found that sulfur-containing compounds present in the early earth’s atmosphere may have given rise to the building blocks of life, according to a research article published Sunday.
Astronomy professor Dimitar D. Sasselov, who directs the Origins of Life Initiative at Harvard, and astronomy graduate student Zoe R. Todd worked alongside Sukrit Ranjan, a postdoctoral fellow at MIT, and John D. Sutherland, a chemist from the University of Cambridge, to devise the refined hypothesis for how life initially arose on Earth.
“We’re interested in the origin of life—how life came about on Earth—and applying that to other planets out there,” Todd said. “So, we’re answering the questions of ‘Are we alone?’ and ‘What other environments might be necessary in order for life to form?’”
Sasselov said scientists previously theorized that sulfur plays a key role in the formation of RNA nucleotides, which are essential for both coding and regulating genetic information.
Todd said the study published Sunday examines the effects of certain environmental conditions—in particular, the presence of sulfur-containing molecules like hydrogen sulfide and sulfur dioxide—on driving prebiotic chemical reactions. These gases were likely produced by erupting volcanoes, he said.
The researchers found that, given the conditions of the early earth, there would be sufficient levels of sulfur dioxide, but insufficient levels of hydrogen sulfide, to give rise to primitive life forms.
“You’re going to have much more of these sulfur dioxide derived anions and much less of the hydrogen sulfide [derived anions],” Todd said. “The sulfur dioxide derived anions might be more valuable for getting this chemistry going.”
“This was not known before,” Sasselov added. “People just assumed that there was enough of this sulfur.”
Todd and Sasselov also emphasized the importance of interdisciplinary interaction between planetary science and chemistry.
“Probably the most valuable part of this study that I took away from it was this synergistic effect between the laboratory and the theory,” Todd said. “The laboratory showed that there’s the need for these sulfur ions in solution, and then they asked us in terms of theory, ‘How might you get this?’ So then, we went to the source, did this study and went back and said, ‘Hey, you might not get enough of what you wanted, but check out this other ion—you might get a lot of that.’”
Sasselov said he thinks the team’s multidisciplinary research moved the ball forward on understanding some of the most fundamental questions about early life.
“When I was a student, I remember people were saying, ‘Don’t even bother to work on the origins of life problems because they are not solvable scientifically,’” Sasselov said. “And to some extent, that’s because they are multidisciplinary. They can’t have just the chemists solve it, or just the astronomers solve it.”
—Staff writer Amy L. Jia can be reached at email@example.com. Follow her on Twitter @AmyLJia.
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