HAMILTON, Canada — In a veritable witch’s cauldron brewing with the potential ingredients for life on Earth, the dust of a meteorite mixed with warm water and, under the sun’s ultraviolet rays, something began making more of itself.
So posits the latest study in favor of the “warm little ponds” theory of the origin of life on earth. Researchers believes that meteorites may have provided essential ingredients into these ponds that bubbled together to form the building blocks of life.
Going well beyond the scope of previous research into the idea, scientists from McMaster University and the Max Planck Institute for Astronomy drew on accumulated knowledge from mathematics, astrophysics, geology, chemistry, and biology to bolster the theory
“Because there are so many inputs from so many different fields, it’s kind of amazing that it all hangs together,” says co-lead author Ralph Pudritz in a press release. “Each step led very naturally to the next. To have them all lead to a clear picture in the end is saying there’s something right about this.”
The researchers contend that their calculations show it was indeed a wet-dry cycle taking place in these so-called warm little ponds that is the most likely origin of life on this planet — rather than a rival theory proposing that life originated in hydrothermal vents on the ocean floor.
Instead of DNA, which the scientists say is too complex to have emerged directly from these ponds, simpler RNA chains are theorized to have been the first life to form. With the components of RNA brought to earth with meteorites, the scientists suggest that some could have ended up in small warm pools of water. As these pools heated up, dried out, and filled again, they say it is possible that the polymers bonded together into chains and eventually, in one chance sequence of events, first folded over and began to spontaneously replicate themselves by drawing in other nucleotides from the pond.
While these first polymers were likely quite flawed, they had achieved one requirement of life by beginning to replicate in a chemical reaction. Once replication began to take place, they would have started naturally selecting as the best replicators continued the reaction.
This improvement fulfills another requirement of life, which we now know as Darwinian evolution.
Indeed, it was Darwin himself who, in a private letter to colleague Joseph Hooker, first used the phrase “warm little pond” to describe this idea of such natural incubators for the first molecules necessary for life.
While the exact sequence of events leading to self-replicating RNA is quite a rare feat of nature, the researchers’ calculations show that the conditions were right in thousands of ponds across the planet. And, it was these ponds that were most likely the origin of life rather than hydrothermal ocean vents, as their research show cycles of wet and dry were needed to bond RNA’s base ingredients.
The hydrothermal vent theory had for a time been a major contender in origin of life studies, but research in 2012 showed that terrestrial volcanic pools seemed to be a more likely place of origin for the first cells due to their chemical makeup.
Now, the most recent study only seems to further cement the idea that life actually didn’t start in the sea, as was once widely thought.
What’s next in these researchers’ quest to investigate the theory? Recreating the conditions in an actual physical experiment. Drawing on the expertise of numerous scientists, they plan to build their own warm little ponds in a sealed environment as soon as next year.
“We’re thrilled that we can put together a theoretical paper that combines all these threads, makes clear predictions and offers clear ideas that we can take to the laboratory,” Pudritz says.
The research was published recently in Proceedings of the National Academy of Sciences of The United States of America.