Drawing on previous research in a number of different scientific fields, the researchers played connect-the-dots, and arrived at a very interesting conclusion.
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. "This is a pretty big beginning". "Each step led very naturally to the next". According to the researchers, the most plausible answer to how life initially formed seems to be that meteorites slammed into ponds here on Earth, prompting the formation of self-replicating RNA molecules thanks to an ideal nutrient makeup of the water.
"Because there are so many inputs from so many different fields, it's kind of incredible that it all hangs together", said Ralph Pudritz of McMaster University, a co-author of the new study.
The study was published today in the Proceedings of the National Academy of Science.
According to the calculations, the "necessary" conditions would have been seen in thousands of ponds across Earth.
Seemingly confirming a concept that has been around since Darwin, these meteorites are believed to have splashed into "little warm ponds" somewhere between 3.7 and 4.5 billion years ago and "leached" essential elements needed for life to begin. "As our study shows, astronomy provides a vital part of the answer. To have them all lead to a clear picture in the end is saying there's something right about this". "The details of how our solar system formed have direct consequences for the origin of life on Earth", says Thomas Henning explained.
The authors plan to test their theory that they can create artificial life in the laboratory next year. Once concentrations in certain pools were sufficient to facilitate bonding, the nucleotides galvanized together through the water cycles of precipitation, evaporation and drainage.
Favourable conditions led some of these newly created molecular chains to fold over and spontaneously replicate themselves, fulfilling one of the conditions for the definition of life.
The basic form of life, RNA, would eventually give rise to DNA, the blueprint of higher forms of life.
"DNA is too complex to have been the first aspect of life to emerge", Professor Pudritz said.
"That's the Holy Grail of experimental origins-of-life chemistry", said Pearce. "It had to start with something else, and that is RNA". 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. Moreover, the rapid losses of nucleobases to pond seepage during wet periods, and to UV photodissociation during dry periods means that the synthesis of nucleotides and their polymerization into RNA occurred in just one to a few wet-dry cycles.
The calculations also appear to rule out space dust being the source of the so-called life-generating nucleotides.
They propose that those ponds may have dried up at some times of the year, concentrating the building blocks of RNA and allowing them to link together - something that's been shown to happen in the lab. Rain would re-form the pond and mix up the building blocks, allowing them to link into longer chains the next time the pond dried up.