Order from Chaos: OoL Version

How did life begin?

Does the Origin of Life (OoL) exemplify order from chaos?

Ancient cosmologies suggest that this is so. In the ancient Egyptian cosmos, the earth and sky are separated from chaos, thanks to gods and goddesses. The Bible book of Genesis begins the creation story with turning chaos into order, by importantly separating the different waters. (Seas were considered ‘chaotic’.) The Babylonian Enuma Elish begins with two god-oceans, Apsu and Tiamat, with conflict leading to creation of the heavens and the earth. Old maps would indicate uncharted waters where chaos reigns. There be dragons. Or Leviathans.

Being unable to experimentally test any of the ancient cosmologies, today’s priesthood of scientists tries to narrow the question. How did seemingly more complex ‘living’ things arise from seemingly simpler things? Inherent in this narrower question are two assumptions: (1) that there is some correlation between life and complexity, and (2) that there is directionality from the simpler to the more complex.

Modern-day research into the chemical origins of life gained momentum starting with the classic Miller experiment (1953). Simple chemicals (methane, ammonia, hydrogen, water) were mixed, and after sparking the mixture with an energy source, lo and behold, seven days later, more complex molecules appear! These include some of the most common amino acids – the building blocks of proteins in all systems we characterize as ‘alive’. In the last sixty years, scientists have successfully synthesized practically all the ‘building block’ molecules of life from simpler substances. Progress has also been made in connecting the building blocks to make larger and more complex systems. Simple to complex – possibly one measure of life increasing from low to higher ‘order’ and conjures up the ‘great chain of being’. (Picture below is one of many from the link.)

Synthesizing more complex ‘life’-like molecules revealed another enigma. These chemical reactions made a very, very, very wide range of molecules, many of which resemble the molecules of life; close cousins you might call them. Extant life only uses a tiny subset of these molecules and it is unclear how or why. This conundrum is known as the Prebiotic Chemist’s Nightmare. It is an embarrassment of riches in the form of a gooey brown or black tar. Somehow selectivity must be involved. Scientists are working hard to uncover the rules that govern such selectivity, or failing that, a plausible contingent pathway that may have led to the particular choices we see in life today. By ‘choosing’ just a few options among the plethora available, life brings some order to the chaos. The narrowing of choices may be one measure of order. If anything and everything goes – well, that’s just chaos.

One area where scientists have made good research progress is in making proto-cells. These cells do not contain everything that is needed for life, but they can self-assemble, divide, and perform chemical reactions. Most origin-of-life scientists agree that encapsulation, forming a boundary that keeps some chemicals inside, and other stuff outside, is an early crucial feature of proto-life. It promotes catalysis, prevents important molecules from being diluted away, and provides a basis for growth, inheritance and evolution. Boundaries. Maybe that’s what brings order to chaos. In a sense, this echoes the ancient cosmologists. By separating the realms, the chaotic ill-defined ‘void’ or sea is brought to order.

The restlessness of the sea – water in its liquid state – brings opportunities for life to flourish. All living cells contain water. The liquid juice may be gooey and viscous, but fluidity allows dynamic motion while preserving structural integrity. This is what makes the liquid phase much more interesting than the solid or the gas phase. Liquids, particularly gooey ones packed with solutes, are also much more difficult to describe in a mathematical model. The behavior of solids and gases turn out to be much easier to model and make predictions about subsequent behavior, i.e., their evolution is perhaps much less interesting. We can in fact describe gases in an orderly way, because after all the word ‘gas’ comes from chaos.

Liquids, on the other hand, operate at the edge of chaos. This is also how most of us in the field would describe life and living systems; they operate at the edge of chaos. Things could turn catastrophic and lead to widespread death, and it all balances on a knife’s edge. For example, DNA error correction mechanisms operate at this very edge, finely balanced with mutation rates and what is barely needed for the next generation to function. If the ability to evolve and diversify is one feature of life, it must operate at the edge of chaos.

So how did life begin? We still don’t know the answer, and it seems that some semblance of order is needed amidst the chaos, be it complexity, selectivity, or defining boundaries. But chaos seems to also play an important role in the richness of life. Perhaps the ancient cosmologists were on to something that we modern day scientists are just starting to glimpse.