The earth was formed for five billion years ago and for many years was hot and battered. It seemed impossible that life, such a delicate creation, could exist in such circumstances. Conventional and complacent wisdom was that the planet cooled, the battering ended, and the power of the sun provided the spark for life to begin. Now we know that that’s wrong, as I’ve learnt from Nick Lane’s magnificent book Power, Sex, Suicide: Mitochondria and the meaning of life.
Molecular biologists have traced back the “molecular clock” and proposed that life began on earth some four billion years ago, when the earth was an intensely hostile place. It seemed impossible that life could begin in such circumstances until scientists made a series of remarkable discoveries of bacteria in unlikely places:
- There are “vibrant bacterial colonies in the high pressures and searing temperatures of sulphurous hydrothermal vents at the bottom of the oceans (known as ‘black smokers’).” This discovery showed in an instant with the “black swan effect” that life can exist without dependence on the sun.
- “Self-sufficient (autotrophic) bacteria live in countless numbers in the ‘deep-hot biosphere’, buried up to several miles deep in the rocks of the earth’s crust. There they scrape a living from the minerals themselves, growing so slowly that a single generation may take a million years to reproduce.”
- “Other bacteria survive radiation at the genetically crippling doses found in outer space, and thrive in nuclear power stations or sterilized tins of meat.”
- “Still others flourish in the dry valleys of Antarctica, or freeze for millions of years in the Siberian permafrost, or tolerate acid baths and alkaline lakes strong enough to dissolve rubber boots.”
Who cannot be excited by the power and range of life? The discoveries might lead to the conviction of the existence of a god or gods, but they also lead to the conviction that if life can begin and flourish in such intensely hostile environments then life must be everywhere in the universe. The universe is infected with life.