Mike Russell found his moment of inspiration on a warm spring evening in Glasgow in 1983, when his 11-year-old son broke a new toy. The toy in question was a chemical garden, a small plastic tank in which stalagmite-like tendrils grew out of seed crystals placed in a mineral solution. Although the tendrils appeared solid from the outside, when shattered they revealed their true nature: each one was actually a network of hollow tubes, like bundles of tiny cocktail straws.
At the time, Russell, a geologist, was struggling to understand an unusual rock he had recently found. It, too, was solid on the outside but inside was full of hollow tubes, their thin walls riddled with microscopic compartments. It dawned on him then that this rock – like the formations in his son’s toy – must have formed in some unusual kind of liquid solution. Russell posited a whole new geological phenomenon to explain it: undersea hydrothermal hotspots where mineral-rich water spewed from Earth’s interior and then precipitated in the cool surrounding water, creating chemical gardens of towering, hollow rocks growing up from the ocean floor.
That was a huge intuitive leap, but it soon led Russell to an even more outlandish thought. ‘I had the epiphany that life emerged from those rocks,’ he said. ‘Many years later, people would tell me the idea was amazing, but it wasn’t to me. I was just thinking in a different realm, in the light of what I knew as a geologist. I didn’t set out to study the origin of life, but it just seemed so obvious.’
What seemed obvious to Russell was that his hypothetical chemical gardens could solve one of the deepest riddles of life’s origin: the energy problem. Then as now, many leading theories of life’s origins had their roots in Charles Darwin’s speculation of a ‘warm little pond’, in which inanimate matter, energised by heat, sunlight or lightning, formed complex molecules that eventually began reproducing themselves. For decades, most origin-of-life research has focused on how such self-replicating chemistry could have arisen. They largely brushed aside the other key question, how the first living things obtained the energy to grow, reproduce and evolve to greater complexity.
But in Russell’s mind, the origin of life and the source of the energy it needed were a single issue, the two parts inextricably intertwined. As a geologist (now working at NASA’s Jet Propulsion Laboratory in California), he came at the problem with a very different perspective from his biology-trained colleagues. Undersea chemical gardens, Russell realised, would have provided an abundant flux of matter and energy in the same place – a setting conducive for self-replicating reactions, and also a free lunch for fledgling creatures. It has long troubled researchers that the emergence of life seems to rely on highly improbable chemical events that lead toward greater complexity. By considering energy first, Russell believed he could address that. In his view, the emergence of biological complexity was not improbable but inevitable. [Continue reading…]