“It IS one of these big questions that we really don’t have a clue about right now,” he says. lena vincent at NASA’s Jet Propulsion Laboratory in Pasadena, California. “Anyone who says otherwise would be skeptical.”
Which is not to say that we lack ideas about how life began on Earth. Rather, all sorts of hypotheses have been advanced to explain how non-living chemicals could self-assemble into a living organism. Some are based on hypothetical self-replicating molecules, some on blob-like structures that could have been the predecessors of cells, while others focus on complex cycles of chemical reactions.
However, none of these ideas has gained widespread acceptance, let alone led to a definitive experiment. As a result, thinking about the origins of life is an exercise in reasoning under uncertainty. It’s about how to tell the difference between a truly promising idea and one that just has a veneer of plausibility.
The truth is that we can’t know for sure exactly how life began on Earth, says Vincent. “We just don’t have access to the part of this planet’s history that would allow us to verify that.” The best we can do is demonstrate the processes that produce life and show that they are compatible with what we know about the early Earth.
For this reason, Vicente prefers to speak of “origins of life”, so as not to imply that we are studying a unique and concrete fact. “It may have happened many times,” he says, and “it may continue to happen” somewhere in the universe.
What matters is whether an experiment that seeks to demonstrate how life…