Charles Darwin & the origin of life

Although best known for his ideas about the origin of species, Charles Darwin also thought about the origin of life on Earth.

In 1871 Darwin described his view of the environment in which life originated; he wrote that life may have appeared: “in some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, etc.”.

Darwin wrote this 80 years before Stanley Miller and Harold Urey synthesized amino acids in their laboratory equivalent of Darwin’s “warm little pond”.

The Miller-Urey experiment is over 50 years old and scientists continue to revise their ideas about the conditions present in the early Earth, and the “warm little pond” scenario has been challenged by other hypotheses including one that life may have arisen under cold conditions. These scenarios will eventually sort themselves out as more research is conducted.

That’s the nature of science.

What is life?

The oldest fossil record of life on earth is photosynthesizing cyanobacteria found in stromatolites. However, photosynthesis is a complex process, and these cyanobacteria probably had precursors that are yet unknown. What were these first hypothetical life forms like?

To answer that question we must first decide on a definition of what constitutes a living thing. This definition is not as clear-cut as it might appear.

Living things grow and reproduce, but inorganic crystals do this, too. Viruses are not regarded as living, as they require a host in order to survive and reproduce, but the existence of viruses highlights the fuzzy line between life and non-life, and reflects the fact that life must have originated from a non-living, “prebiotic” stage.

The British biologist J.B.S. Haldane concluded that “The line between living and dead matter is …somewhere between a cell and an atom.”

Photo and information on research on artificial life here.