In the great “mythmaking” that is the scientific process, discovering things about events long lost to history is done a little bit differently than the method might suggest in more mundane circumstances. We develop plausible hypotheses regarding events like the abiogenesis event that occurred here on Earth, and then test them rigorously attempting to falsify each one in turn. Like Sherlock Holmes, or Dr. House, we’ll get to the kernel of the matter by eliminating all the alternatives until we are left with but one plausible truth. We know we’re on the right track when predictions about certain aspects of the theory are demonstrable in laboratories.
We may never learn the exact nature of the exact abiogenesis event that led to us (among multiple possible such events) any more than we’ll know the exact daily routine, shape, facial features, birthday or date of death of the single individual last common ancestor (among multiple possible last common ancestors of that ancestor’s species) between us and chimpanzees, but we know (by genetic and fossil evidence) that we are not that far removed. This should not matter in the investigation of how it could have happened — despite the fact that there are many theories about the event of abiogenesis. We know the first chemicals breached that fuzzy boundary between “mere chemical reaction” and “self-perpetuating chemical reaction” — in other words, between non-life and life — so we know abiogenesis had to happen somewhere. If it didn’t happen here, and we got here by panspermia, then it happened elsewhere in the universe first, but it happened once at the very least.
New research has been very promising as of late with regard to the greatest mystery our planet yet holds, potentially unlocking each of the sub-mysteries one at a time with plausible answers. One of these sub-mysteries involves the chirality of all life on Earth — every amino acid this planet uses as its biological Lego can exist in a right-handed or a left-handed form and would spontaneously form either one at identical odds, but every speck of life on this planet uses only the left-handed version. With our ever-improving knowledge of the early environment of the planet, we’ve discovered that aspartic acid trends sinistral, creating left-handed versions in large quantities in a crystalline structure under those conditions. This certainly does not confirm the theory, but it provides a good hypothetical “seed” that explains how the amino acids that form us all tended to be left-handed.
There’s also the question of why those simple building blocks like aspartic acid might have influenced the other amino acids that self-generated in the environment to follow suit in their chirality. So, scientists built on the earlier result and introduced the left-handed acids into an environment with equal proportion left- and right-handed amino acids, and found the left ones crystallized much like the aspartic acid crystal in the earlier experiment.
“These amino acids changed how the reactions work and allowed only the naturally occurring RNA precursors to be generated in a stable form,” said Hein. “In the end, we showed that an amazingly simple result emerged from some very complex and interconnected chemistry.”
The natural enantiomer of the RNA precursor molecules formed a crystal structure visible to the naked eye. The crystals are stable and avoid normal chemical breakdown. They can exist until the conditions are right for them to change into RNA.
This experiment had every possibility of falsifying the earlier hypothesis but it did not. More research will either disprove both these hypotheses, or confirm them repeatedly over many iterations until our confidence level has increased so that they’re the best plausible explanations. Or, who knows? Perhaps we’ll one day unearth some new evidence, and we’ll need a better explanation to incorporate that new knowledge.
That’s how science works.