Rocky ground
Rocky ground: Papineau's key sample came from this formation of hematite and magnetite. Courtesy Dominic Papineau and Matthew Dodd

Ancient Greece

Leading thinkers conjecture that life arose spontaneously—just as maggots seem to appear on carcasses.


Charles Darwin writes that life may have emerged in a “warm little pond” with the right mixture of light, heat, and chemicals.


Svante Arrhenius popularizes the theory of panspermia—the notion that life was seeded by comets from outer space.


Alexander Oparin and John Haldane independently theorize life began in a primordial “soup” of organic compounds.


Stanley Miller and Harold Urey show building blocks of life can form in water when electricity zaps key ingredients.


Discovery of living creatures near deep-sea hydrothermal vents opens a new origin-of-life frontier.


Walter Gilbert proposes that life starts with RNA molecules combining, separating, and evolving.


Fossils called stromatolites found in 3.4-billion-year-old rocks in Australia—the oldest accepted evidence of early life.


The Deep Carbon Observatory seeks the origins of carbon-based life miles inside Earth.


Researchers propose that life originated in geothermal ponds on land instead of in the deep sea.

This article was originally published in the September/October 2017 Mysteries of Time and Space issue of Popular Science.