The Origin of Life

The origin of life is one of the most iconic questions in science. Work over decades has seemingly made good progress in synthesizing the basic building blocks of life under purportedly 'prebiotic' conditions, such as the nucleotides that make up the genetic material in DNA. However, there is a serious disconnect between this prebiotic chemistry and the actual biochemistry of known cells in almost every respect. To close this gap between geochemistry and biochemistry and elucidate the fundamental rules of life, we propose a different approach to the problem, grounded in life itself.

We take as our starting point an important rule of life - energy flow across membranes. This feature of life is as deeply conserved across the tree of life as the genetic code itself. Yet while the importance of energy flow in biology cannot be overstated, the origin and evolutionary implications of the specific mechanism involved has historically been neglected. Recent work on reconstructing the properties of the earliest cells is now opening up new possibilities.

Our overarching hypothesis is that the flow of protons across membranes can drive the difficult reaction between carbon dioxide and hydrogen gas to form the carbon 'skeletons' that are used to make all the other building blocks of cells. We propose that analogous processes can be driven in structured prebiotic environments such as hydrothermal vents, giving rise to the familiar metabolism and biochemistry of cells. In particular, we hypothesize that genetic information first arose in this setting. Genetic heredity is strictly another form of growth, in which a genetic template is repeatedly copied (doubled) and passed on. We propose that its mysterious origins (which have resisted interpretation over decades, despite many clues) can best be understood in the context of actively growing protocells, driven by energy flow through a structured environment.

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(Image: IFE / URI-IAO / UW / Lost City Science Party / NOAA / OAR / OER)