How Did Life On Earth Begin?

Earth is unlike any other planet we know of by virtue of hosting life – and not just in a single form, life is present in a rich variety of species. But, as MICHAEL MARSHALL explains, we still don’t know what got it started

- Michael Marshall

Open your eyes anywhere on Earth and there is life: whether it’s a pigeon or the invisible microorganisms coating every surface. But when the planet was born 4.5 billion years ago, it was sterile. How did the first life emerge?

The short answer is we don’t know. If we did, we could reproduce it. Scientists could put the right chemicals in a sealed container under the correct conditions and when they opened it, they’d find living organisms. Nobody has ever done this.

But while we don’t know exactly how life began, we have a lot of clues.

Let’s start with the easiest bits: what is life made of and where did those components come from? Living organisms contain thousands of chemicals: like proteins and nucleic acids that carry our genetic information. These chemicals are complex, but we now know that their constituent parts form quite readily.