One of the greatest puzzles of all time is how did life arise? It has been universally presumed that life arose in a soup rich in carbon compounds, but from where did these organic molecules come?

Although Darwin’s Origin of Species is still widely believed by many to refer to the origin of life, this was not a question the book addressed. His book was instead about where existing species come from. The short answer is that they are genealogically descended in an unbroken reproductive series from earlier species. But what did Darwin think about the origin of life? In the Origin of Species he wrote ‘I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed.’ Although a few years later in 1863 Darwin wrote to his friend the botanist Joseph Dalton Hooker: ‘I have long regretted that I truckled to public opinion and used Pentateuchal term of creation, by which I really meant “appeared” by some wholly unknown process.—It is mere rubbish thinking, at present, of origin of life; one might as well think of origin of matter.’ Yet despite these cautious protestations we can clearly glean from his occasional references to the origin(s) of life that Darwin believed that life arose by purely natural causes as simple micro-organisms in an aquatic environment on Earth.