Physics Theory of Life

“Take chemistry, add energy, get life. The first tests of Jeremy England’s provocative origin-of-life hypothesis are in, and they appear to show how order can arise from nothing.”

“His equations suggested that under certain conditions, groups of atoms will naturally restructure themselves so as to burn more and more energy, facilitating the incessant dispersal of energy and the rise of “entropy” or disorder in the universe.”

“England said this restructuring effect, which he calls dissipation-driven adaptation, fosters the growth of complex structures, including living things.”

“The existence of life is no mystery or lucky break, he told Quanta in 2014, but rather follows from general physical principles and “should be as unsurprising as rocks rolling downhill.””

“The paper strips away the nitty-gritty details of cells and biology and describes a simpler, simulated system of chemicals in which it is nonetheless possible for exceptional structure to spontaneously arise — the phenomenon that England sees as the driving force behind the origin of life. “That doesn’t mean you’re guaranteed to acquire that structure,” England explained. The dynamics of the system are too complicated and nonlinear to predict what will happen.”

“for some initial settings, the chemical reaction network in the simulation goes in a wildly different direction: In these cases, it evolves to fixed points far from equilibrium, where it vigorously cycles through reactions by harvesting the maximum energy possible from the environment. These cases “might be recognized as examples of apparent fine-tuning” between the system and its environment, Horowitz and England write, in which the system finds “rare states of extremal thermodynamic forcing.””

“Living creatures also maintain steady states of extreme forcing: We are super-consumers who burn through enormous amounts of chemical energy, degrading it and increasing the entropy of the universe, as we power the reactions in our cells. The simulation emulates this steady-state behavior in a simpler, more abstract chemical system and shows that it can arise “basically right away, without enormous wait times,” Lässig said — indicating that such fixed points can be easily reached in practice.”

“England, a prodigy by many accounts who spent time at Harvard, Oxford, Stanford and Princeton universities before landing on the faculty at MIT at 29, sees the essence of living things as the exceptional arrangement of their component atoms.”

“It’s not easy for a group of atoms to unlock and burn chemical energy. To perform this function, the atoms must be arranged in a highly unusual form. According to England, the very existence of a form-function relationship “implies that there’s a challenge presented by the environment that we see the structure of the system as meeting.””

“But how and why do atoms acquire the particular form and function of a bacterium, with its optimal configuration for consuming chemical energy? England hypothesizes that it’s a natural outcome of thermodynamics in far-from-equilibrium systems.”

“Coffee cools down because nothing is heating it up, but England’s calculations suggested that groups of atoms that are driven by external energy sources can behave differently: They tend to start tapping into those energy sources, aligning and rearranging so as to better absorb the energy and dissipate it as heat.”

“He further showed that this statistical tendency to dissipate energy might foster self-replication. (As he explained it in 2014, “A great way of dissipating more is to make more copies of yourself.”) England sees life, and its extraordinary confluence of form and function, as the ultimate outcome of dissipation-driven adaptation and self-replication.”

“However, even with the fluctuation theorems in hand, the conditions on early Earth or inside a cell are far too complex to predict from first principles. That’s why the ideas have to be tested in simplified, computer-simulated environments that aim to capture the flavor of reality.”

“In the PRL paper, England and his coauthors Tal Kachman and Jeremy Owen of MIT simulated a system of interacting particles. They found that the system increases its energy absorption over time by forming and breaking bonds in order to better resonate with a driving frequency. “This is in some sense a little bit more basic as a result” than the PNAS findings involving the chemical reaction network, England said.”

“when the researchers let the chemical reaction networks play out in such an environment, the networks seemed to become fine-tuned to the landscape. A randomized set of starting points went on to achieve rare states of vigorous chemical activity and extreme forcing four times more often than would be expected. And when these outcomes happened, they happened dramatically: These chemical networks ended up in the 99th percentile in terms of how much forcing they experienced compared with all possible outcomes.”

“As these systems churned through reaction cycles and dissipated energy in the process, the basic form-function relationship that England sees as essential to life set in.”

“Experts said an important next step for England and his collaborators would be to scale up their chemical reaction network and to see if it still dynamically evolves to rare fixed points of extreme forcing. They might also try to make the simulation less abstract by basing the chemical concentrations, reaction rates and forcing landscapes on conditions that might have existed in tidal pools or near volcanic vents in early Earth’s primordial soup (but replicating the conditions that actually gave rise to life is guesswork).”

“But even if the fine-tuned fixed points can be observed in settings that are increasingly evocative of life and its putative beginnings, some researchers see England’s overarching thesis as “necessary but not sufficient” to explain life, as Walker put it, because it cannot account for what many see as the true hallmark of biological systems: their information-processing capacity.”

“From simple chemotaxis (the ability of bacteria to move toward nutrient concentrations or away from poisons) to human communication, life-forms take in and respond to information about their environment.”

“Gunawardena noted that aside from the thermodynamic properties and information-processing abilities of life-forms, they also store and pass down genetic information about themselves to their progeny. The origin of life, Gunawardena said, “is not just emergence of structure, it’s the emergence of a particular kind of dynamics, which is Darwinian. It’s the emergence of structures that reproduce. And the ability for the properties of those objects to influence their reproductive rates. Once you have those two conditions, you’re basically in a situation where Darwinian evolution kicks in, and to biologists, that’s what it’s all about.””

“Sarpeshkar seemed to see dissipation-driven adaptation as the opening act of life’s origin story. “What Jeremy is showing is that as long as you can harvest energy from your environment, order will spontaneously arise and self-tune,” he said. Living things have gone on to do a lot more than England and Horowitz’s chemical reaction network does, he noted. “But this is about how did life first arise, perhaps — how do you get order from nothing.””