With a plausible mechanism for joining amino acids together, scientists began to explore the idea that these molecules could be the first living biological structures.
Andrew Pohorille is one of these scientists. As director of the Center for Computational Astrobiology at NASA’s Ames Research Center in Mountain View, California, Pohorille is using a computer to model how the hodgepodge of Earth’s early molecules might have assembled into peptides that can catalyze reactions. Pohorille and his colleague Michael New designed a computer model that reenacts the early steps in life. On the computer, they create imaginary peptide chains of various lengths. By running the computer program, they simulate how peptide chains randomly encounter each other and form longer, more complex strands.
In Pohorille’s model, the short peptides interact with each other for a prescribed amount of time, hooking up and breaking up. Once in a while, purely by random meetings, the peptides form a catalyst, able to incite nearby chemical reactions.
Pohorille has found that over time his peptides evolve into longer chains that become better and better at their task of catalyzing the formation of other nearby peptides. Since the process is random, however, there is always a chance that instead of forming a matchmaker, the system will produce the opposite: a catalyst that breaks up peptides. But this is not all bad, says Pohorille. He thinks these peptide-breakers could break up dysfunctional partnerships, thus freeing them to find better-suited partners.
Although some critics are skeptical of Pohorille’s work because they think the chances are slim that peptides can spontaneously form catalysts, others think he is on the right track.
Jean Chmielewski, a protein chemist at Purdue University in Lafayette, Indiana, has created peptides that can replicate in test tubes. She and post-doctoral researcher Shao Yao built a 35-amino-acid-long chain capable of copying itself, a task peptides normally cannot do.
This is one of the closest things I could find to the assumptions of Watson. There are some fundamental differences, however, that I think make this differ greatly from Watson's assumptions. Mind you, this is pretty far afield from even his basic assumptions. This isn't even DNA life we are talking about, and we are not talking about base pair accumulation.
One. The peptide chains don't have to start over if they hit a dead end. A reaction that splits it into two small functioning peptide chains means that are not starting over completely from step one, which is a critical assumption in the Watson model.
Two. It isn't truly random, since the chemical reactions are guided by catalysts, which accelerate certain reactions at the expense of others. The presence of a pro-life catalyst could accelerate reactions beyond what Watson predicts, and it also decreases randomness from the equation, as it preferentially chooses certain reactions.