Consider the possibility of alien life on other planets that differs from Earth’s. How might they appear, and why would they be so different from one another?
According to Juan Pérez-Mercader, it might be true, and the explanation might be that they emerged from a different kind of chemistry. The senior research fellow at Harvard’s Origins of Life Initiative and Department of Earth and Planetary Sciences has been studying how to create synthetic living systems without relying on biochemistry or the chemistry that gave rise to life on Earth for more than a decade.
According to Pérez-Mercader’s explanation, “We have been trying to build a non-biochemical system that is unaided and capable of executing the essential properties common to all natural living systems.”
The most recent study by the Pérez-Mercader lab, which was published last month in Cell Reports Physical Science, even reveals that such a system is engaged in “the struggle for life,” as Charles Darwin put it. The paper highlights Pérez-Mercader with co-creators Sai Krishna Katla and Chenyu Lin, depicting how they made two manufactured models (or “species”) and noticed the resulting rivalry between them.
“It’s possible that there are materials that, once on a planetary surface somewhere with suitable conditions, could react chemically, self-organize, and possibly do the things that this experiment demonstrates,”
Juan Pérez-Mercader
“I accept that we ought to be exceptionally open about different types of life somewhere else in the universe and that they may not look like life as we remember it currently,” says physicist Juan Pérez-Mercader. Credit: Kris Snibbe/Harvard Staff Picture Taker
Well before this review, the lab sorted out some way to make non-biochemical, but carbon-science-based, frameworks called protocells. These are self-assembling polymer vesicles that come from a uniform mixture of smaller synthetic chemicals that have no connection to living things. “These frameworks behave like biochemical cells,” Pérez-Mercader noted. “They emerge from the womb, consume what they require, develop, move, reproduce, and possibly even evolve.”
The next step for the researchers was to determine whether or not the evolutionary principle of competitive exclusion would apply to these systems. The struggle for survival involves the species with the greatest competitive advantage edging out the others when competing for resources, as Darwin’s work demonstrates.
For this particular study, Pérez-Mercader and his team created two new species of protocells, one with light sensitivity and the other without. The researchers observed that the light-sensitive “species” survived while the others did not, as these systems shared food in an illuminated environment. According to Pérez-Mercader, “it’s the struggle for existence where the best-suited structure survives in its environment.”
Pérez-Mercader is willing to suggest, based on these findings, that biochemicals are not necessary for survival. This demonstrates the way that non-biochemical carbon science can prompt the annihilation of the less ‘fit’ protocell species,” he said.
The findings of his team raise the question: Could life’s fundamental properties be implemented by chemistry on other planets?
“It’s conceivable that there are materials that, once on a planetary surface in some place with suitable circumstances, could respond synthetically, self-assemble, and maybe do the things that this investigation shows,” Pérez-Mercader said.
He stated, “These materials may evolve from very simple chemistry into more complex structures under the right conditions.” I think we ought to be very open about the possibility of other forms of life elsewhere in the universe that might not resemble life as we currently understand it.
More information: Sai Krishna Katla et al, Competitive exclusion principle among synthetic non-biochemical protocells, Cell Reports Physical Science (2023). DOI: 10.1016/j.xcrp.2023.101359
