Philipp Ammon for Quanta Magazine.

What if life arose in a geological environment where electrochemical gradients across tiny barriers occurred naturally, supporting a primitive form of metabolism while cells as we know them evolved.

Lane has explored this provocative idea in a variety of journal papers, and he has touched on it in some of his books, such as The Vital Question, where he wrote, “Carbon and energy metabolism are driven by proton gradients, exactly what the vents provided for free.” He describes the idea in more detail for the general public in his latest book, Transformer: The Deep Chemistry of Life and Death.

In his view, metabolism is central to life, and genetic information emerges naturally from it rather than the other way around.

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His hypothesis that life started with primitive metabolic reactions in deep-sea hydrothermal vents illuminates the outsized role that energy may have played in shaping evolution.

Photo by Philipp Ammon for Quanta Magazine;?

for Quanta Magazine.

Let’s start with what life is starting with: hydrogen and carbon dioxide, which don’t react very easily.

As we see in mitochondria and in certain bacteria, life uses an electrical charge on the membrane to transfer electrons from hydrogen onto iron sulfur proteins like ferredoxin.

You get these minerals in hydrothermal vents, and you also get carbon dioxide and hydrogen, and there are even thin barriers in the porous rock with an electrical charge on them.

The question is: Does this structure at the vents effectively drive the reaction between carbon dioxide and hydrogen.

We don’t get a lot, but we’re getting more as we begin to optimize our process, and what we’re seeing produced is Krebs cycle intermediates.

Philipp Ammon for Quanta Magazine.

Philipp Ammon for Quanta Magazine.

We often focus on the Krebs cycle performing the same energy-generating reactions over and over.

In our mitochondria, it strips carbon dioxide and hydrogen out of intermediate molecules to generate an electrical charge on a membrane for energy.

And it’s not just in ancient bacteria — our cells still use the Krebs cycle for biosynthesis too.

We’ve known since the 1940s that the Krebs cycle can sometimes run backward in our cells, and that its intermediate molecules are sometimes used as precursors for making amino acids.

The Krebs cycle never really operated as a true cycle except in the most highly energetic cells, like the flight muscles of pigeons, where it was first discovered.

In most cells, the Krebs cycle is more like a roundabout than a cycle, with things coming in and going out at different points.

Cells run the biochemical process called the Krebs cycle in both directions as needed to balance their needs for energy generation and biosynthesis.

Philipp Ammon for Quanta Magazine.

About 10 years ago, the cancer community was amazed by the discovery that in some cancers, mutations can lead to parts of the Krebs cycle running backward.

It came as quite a shock because the Krebs cycle is usually taught as only spinning forward to generate energy.

So the whole field of oncology began to see this reversal of the Krebs cycle as a kind of metabolic rewiring that helps cancer cells grow.

In effect, cancer cells switch from burning oxygen in their mitochondria for respiration to fermenting for energy like yeast cells, even in the presence of oxygen.

By switching to aerobic glycolysis for energy, cancer cells free up their mitochondria for other purposes.

Cancer cells have biosynthetic mitochondria for making the building blocks of life.

That means we will have less energy; it means that we will begin to put on weight because we start turning carbon dioxide that we would exhale back into organic molecules.

Our risk of diseases like cancer increases because we have a metabolism that is prone to that kind of growth.

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