Tomato Sauce and the Origin of Life

I love cooking. And my specialty is tomato sauce. I inherited it from my grandmother and improved it with my Italian aunts. 

Modesty aside, it’s a spectacle. Once, while giving the last boil before starting the long process of cold counting, I saw them there… beautiful… some ‘Benard cells‘. 

Well… weren’t perfect ones. Maybe it was wishful thinking that they would appear like this, far from ideal controlled conditions, to decorate my tomato sauce. Or maybe I saw them because I was finally ready to understand what ‘Benard cells’ are and why they are so important.

I first heard of them in 1997, when I was starting my PhD in Biophysics at the Federal University in Rio de Janeiro. I took an incredible ‘Philosophy of Science’ course, where I had, among many others, an incredible class with a physicist Paulo Bisch, who had been an intern in the laboratory of the great chemist Ilya Prigogine, Nobel Prize for his studies in thermodynamics and for the discovery of dissipative structures (which is what Benard cells are).

Thermodynamics is very simple and at the same time incredibly complicated. I’ll try to keep it simple. The one thing you need to know about thermodynamics is that its laws are among the fundamental laws of the universe and if something goes against them, then that thing has problems.

So imagine how people were surprised when they realized that life apparently going against the laws of thermodynamics.

The 2nd law of thermodynamics states that heat will always move from the hottest body to the colder one, and never the other way around, until they reach the same temperature. A consequence of that is that dispersion, random dispersion, not concentration, is the rule. And thus things tend to disorganisation.

So how can we be highly organized beings and keep or even gain organization over time while everything in the universe loses organization over time? The answer involves large amounts of energy and Benard cells.

Benard cells are just one example of the ‘stable systems far from thermodynamic equilibrium’, which was what most intrigued Prigogine. The ‘cells’ you are seeing are little swirls of water on a plate. What Prigogine calls ‘out of thermodynamic equilibrium’ means it has a heat source, like the fire on the stove top, heating up something, like the petri dish of water, or my pot of tomato sauce. With no heat source, even if two bodies initially have a different temperature, the hotter body will pass heat to the colder body until they are both at the same temperature. This is thermodynamic equilibrium. But with the heat source… the warmer body passes heat to the cooler body, but they never arrive at the same temperature.

And this is what happens when you heat water to make coffee or tea: near the fire it is hotter and near the surface it is colder (or less hot) until… the water starts to boil. It is no longer just the heat that rises through the water column. Warmer water is less dense and rises to the top of the water column (inside the pot, or kettle). The surface water is cooler and denser, and sinks to the bottom of the pot. A convection movement is then formed (cold water always descends on one side and hot always rises on the other). It is literally a ‘waterfall’ of less hot water and a ‘geyser’ of warmer water, which feed on each other: when the geyser reaches the surface of the water column, it passes heat to the air and the water cools. It cools down enough to increase its density and precipitate in the waterfall that leads to the bottom of the pot, where the heat of the fire heats the water until it loses density and rises in the ‘geyser’ and repeats the process. Viewed from above, the ‘waterfalls’ are at the centers of the cells, the darkest part, and the ‘geysers’ are at the ends of the cells.

The regularity of these structures impressed chemists and physicists at the time. How could an out-of-equilibrium system generate order? This seemed to go against the 2nd law of thermodynamics. But actually it wasn’t, because the formation of ‘Benard cells’ allowed more heat to be transferred, and faster, from water to air. Or from the source to the air through the water. It was then that Prigogine had the big insight: when an out-of-balance system (such as water inside the kettle over the fire to make coffee) reaches a critical moment, the order appears to allow a more efficient heat exchange between the two systems. He called this phenomenon ‘self-organization’ and the ordered structures ‘dissipative structures’ because they allow the system to dissipate, transfer, more heat to the medium.

Truly understanding that, that day cooking the tomato sauce, years after the philosophy class in 1997, was an intellectual accomplishment for me. And necessary one. Because that class changed a lot of things to me. To start, it put the final nail in the coffin and God for me was then definitely dead. It made clear to me that the last bastion of magic had fallen and there was no longer a ‘why’ or a ‘what for’ the creation of life: life was an inevitable outcome of thermodynamics, a self-organizing dissipative structure at a critical point in our planet’s thermodynamically open system. But without really, truly understanding it, I was simply repeating something I heard and believed in. But now I can explain that we are like Bernard cells, Earth is like the kettle whose function is to dissipate the energy coming from the Sun. And, like any dissipative structure, our (life) appearance was inevitable, once the system reaches the critical point.

We further disorganize the universe so that we can swim against the current and remain highly organized.

After that, I’ll leave it to Darwin, in the final part of the beautiful movie ‘Creation’, which I just finished watching.

“It is from the war of nature, from hunger and death, the most sublime thing that we are capable of conceiving, namely, namely, the production of the higher animals, comes. There is greatness in this way of looking at life, that while this planet has been rotating according to the fixed law of gravity, from a very simple beginning, infinite forms, the most beautiful and the most wonderful, have evolved and continue to evolve.”

This content was first published in Portuguese in the ‘Você que é biólogo…’ blog in May 9, 2011