I am a believer in knowing where we have come from and this piece is dedicated to finding out how life began. Over the last century, a few scientists have tried to figure out how the first life might have sprung up.
Life is old. The dinosaurs are perhaps the most famous extinct creatures, and they had their beginnings 250 million years ago. But life dates back much further. In August 2016, researchers found what appear to be fossilised microbes dating back 3.7 billion years. The Earth itself is not much older, having formed 4.5bn years ago.
Since the 19th Century, biologists have known that all living things are made of cells after the first modern microscopes were invented, but it took well over a century for anyone to realise that they were the basis of life.
By far the most numerous forms of life are micro-organisms, each of which is made up of just one cell. Bacteria are the most famous group, and they are found everywhere on Earth. Every living thing, including you, is ultimately descended from a bacterium.
In 1952, Stanley Miller began the most famous experiment on the origin of life ever attempted. He connected a series of glass flasks and circulated four chemicals that he suspected were present on the early Earth: boiling water, hydrogen gas, ammonia and methane. He subjected the gases to electric shocks, to simulate the lightning strikes that would have been common back then.
Miller found that “the water in the flask became noticeably pink after the first day, and by the end of the week the solution was deep red and turbid”. When analysed, the mixture contained two amino acids: glycine and alanine. Amino acids are the building blocks of life. They are used to form the proteins that control most biochemical processes in our bodies. Miller had made two of life’s most important components, from scratch.
While Miller was trying to make the stuff of life from scratch, other scientists were figuring out what genes were made of. By this time, many biological molecules were known. These included sugars, fats, proteins and nucleic acids such as “deoxyribonucleic acid”, or DNA for short.
During its first half-billion years of existence Earth was pounded by meteorites mostly made of metal. Crucially, meteorite impacts melt the Earth’s crust, leading to geothermal activity and hot water.
Scientists have concluded rivers trickled down the slopes of impact craters leaching cyanide-based chemicals from the rocks while ultraviolet radiation poured down from above. Each stream would have a slightly different mix of chemicals, so different reactions would happen and a whole host of organic chemicals would be produced.
The streams would flow into volcanic ponds at the bottom of the crater where all the pieces came together, and the first protocells formed. This means that, for the first time in history, we have the beginnings of a comprehensive explanation for how life began.
This knowledge will change us. On a purely scientific level, it will tell us about how likely life is to form in the Universe, and where to look for it. And it will tell us something about life’s essential nature.
Finally, let’s hope that humankind recognises that through our self-centred destructive actions we are undoing 4.5bn years of development. Earth is the only place we know where all the right constants of nature have come together to create the right conditions for life. Let’s not be the generation responsible for its destruction.
Gordon is the former president and chief executive of BMMI. He can be reached at [email protected]