Rocks rolling downhill
How did life first originate from nothing? This has been the focus of biologists, specifically astrobiologists, and popular theories have included everything from meteorites to seemingly random chemicals to luck. In 1859, Charles Darwin posited that “All organic beings that have lived on Earth could be descended from some primordial form,” in The Origin of Species. His basic idea was that chemical components and energy sources somehow spontaneously generated life in the primordial soup.
However, in 2013, MIT biophysicist Jeremy England proposed a new theory that substituted thermodynamics in place of luck. He derived a mathematical formula to explain how atoms, driven by external energy (such as that found in primordial soup) and heat (like you’d find in an atmosphere), will gradually restructure themselves to dissipate more and more energy. In other words, under the right conditions, matter naturally acquires the basic physical quality — the tendency to capture energy from the environment and dissipate it as heat — associated with life, based on the law of increasing entropy or the second law of thermodynamics, also called the “arrow of time.”
If this theory is right, England commented in 2013, luck has nothing to do with it, and life should evolve following those laws and “should be as unsurprising as rocks rolling downhill.”
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The arrow of time
England has since been testing his formula and his idea more generally using computer simulations. He published two studies in July, and both experiments appear to support his basic theory about adaptation driven by dissipation. However, what these results ultimately mean for the origins of life remain unclear.
In the simulation, a soup of 25 chemicals reacted together in multiple ways as environmental sources of energy “force” certain chemical reactions, just like ATP provides the chemical fuel for cellular metabolism. In some cases, the system reaches an equilibrium state, the most familiar outcome produced by the second law of thermodynamics. However, in other cases, the chemical reaction network evolves as reactions harvest as much energy from the environment as possible, ending at fixed points far away from equilibrium.
These “rare states of extremal thermodynamic forcing” are similar to the extreme forcing that living creatures engage in as we burn up chemical energy. England believes that atoms acquire the very specific form and function designed for optimal chemical energy consumption and become a bacterium because thermodynamics dictates this natural outcome in far-from-equilibrium systems. Many biophysicists agree with England, but since there is still disagreement about what the essence of life is, it’s difficult to nail down how explanatory this theory is in terms of life’s origins.
So, what’s next? Perhaps physically simulating primordial soup outside of a computer environment is the next step, but this does involve some guesswork. And, while England sees his theory as underlying Darwinian evolution, some disagree that this dissipation-driven adaptation theory could distinguish between things that are simply structured in a certain way and things that are alive. For example, the ability to perceive, process, and pass on information in the form of reproduction may not be fully explained by England’s theory. In any case, this work provides fascinating insights into one possible explanation of how our planet made something out of nothing.