It’s not a plot from Hollywood’s latest science fiction thriller, but a legitimate theory that has gained traction in some scientific circles and was recently proven mathematically by a team of researchers based in Canada and Germany.
Ben K.D. Pearce and Ralph Pudritz – scientists from McMaster University in Canada – published a paper Monday theorizing that chemicals inside asteroids falling to earth seeped into shallow pools warmed by the sun, and spawned the first genetic code that would evolve over centuries into a teeming panoply of life.
"No one's actually run the calculation before," Pearce said. "This is a pretty big beginning. It's pretty exciting."
The “warm little ponds” theory has been around since the times of Charles Darwin, when the theory of evolution first gained traction in scientific communities. But Pearce and Pudritz actually ran calculations using genetic sequencing and in a sense, their studies prove the math.
"Because there are so many inputs from so many different fields, it's kind of amazing that it all hangs together," Pudritz said. "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 scientists also worked with physicists Dmitry Semenov and Thomas Henning of the Max Planck Institute for Astronomy in Germany, and together their paper was published in the Proceedings of the National Academy of Science.
Their results mathematically prove a theory that chemicals from meteorites splashed down into warm nutrient-rich pools or ponds, which then underwent wet and dry cycles that eventually produced self-replicating RNA molecules with genetic codes.
RNA polymers are essentially the spark of life on earth, the researchers say in the report, with asteroids delivering the essential component of nucleotides. Once concentrations in certain pools were sufficient to facilitate bonding, the nucleotides galvanized together through the water cycles of precipitation, evaporation and drainage.
If conditions were favorable, the RNA chains that formed began to fold over themselves and replicate themselves by drawing nucleotides from the environment thereby fulfilling one of the necessary conditions for life. These polymers were imperfect, according to the math conducted in the new research, meaning they provided a necessary template for evolution, one of the other conditions of life.
“That's the Holy Grail of experimental origins-of-life chemistry," says Pearce.
The imperfect RNA polymers provide the basis for DNA, the foundational blueprint for all higher forms of life, which likely took untold centuries to emerge from those basic polymers, the study says.
"DNA is too complex to have been the first aspect of life to emerge," Pudritz said. "It had to start with something else, and that is RNA."
Calculations made by the researchers show that conditions necessary to give rise to the spark of life were present in thousands of ponds across the surface of the earth. The study also casts doubt on the most significant rival theory, which asserts that life emerged from the interaction of hydrothermal vents on the bottom of the ocean.
Pearce and Pudritz say the conditions in the small ponds is significantly more likely than the roiling hydrothermal vents theory propounded by other origin-of-life scientists. Furthermore, life needed both wet and dry cycles to form, something not possible at the intersection of the hydrothermal vents on the bottom of the floor.
The ocean floor theory also discounts the instrumental role played by space dust, during a time when asteroids were far more common.
“The details of how our solar system formed have direct consequences for the origin of life on Earth," Henning said.
Pearce and Pudritz are not finished with the theory, as they are slated to run an experiment at McMaster University’s Origins of Life lab that will recreate the conditions in a sealed environment.
"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 said.
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