Stephen Hawkins recently said that science ‘can explain the light of stars but not the lights that shine from Planet Earth.’ Where did we come from? Why are we here? Most importantly, are we alone? Whatever the answers, they will be incomprehensibly profound and of unique importance to the human race—the universe either teeming with advanced civilisations or utterly empty, life on Earth being just one big, lonely cosmic accident. A huge step towards answering these questions could lie in unraveling the mystery of how life arose here on Earth in the first place. In the spirit of such discovery, here are five amazing theories about our own origins.
1. The Primordial Soup
Darwin famously conceived of a ‘warm little pond’ where life might have first arisen. This is a controversial theory that has moved in and out of favour over the years, mainly because the atmospheric conditions of early Earth are poorly known. Did warm little ponds exist three billion years ago? We just don’t know.
2. Deep-Sea Vents
An increasingly likely theory is that life might have originated deep below the waves, around warm oceanic vents. Species have been discovered here that are completely independent of sunlight, thriving instead on chemosynthesis using inorganic compounds such as hydrogen sulphide spewing from geysers. Our best bet for proving this theory would be to discover life around vents that may exist on moons such as Jupiter’s Europa.
3. Panspermia
Photo by Marcel Clemens
Perhaps life didn’t start on Earth at all. Perhaps it was seeded across the solar system or even the universe in the form of tiny organisms hitching a ride on asteroids or comets. If scientists can find organic compounds in space, it will go a long way towards supporting this theory. Some commentators whisper that it’s even possible aliens seeded us deliberately.
4. The Deep-Hot Biosphere Theory
Photo by Naeblys / Shutterstock
Digging even deeper than the deep-sea vents, Thomas Gold proposed a theory in the 1970s that life might have arisen far below the planet’s surface, based on a continuous supply of primordial methane from the Earth’s mantle. He postulated that if life arose in a ‘warm little pond’ then it would rapidly run out of food. Some of our more sophisticated spacecraft are now designed to drill just below alien surfaces, so finding life underground here might be the smoking gun for this theory’s viability.
5. The Radioactive Beach Hypothesis
Finally—for something a little ‘out there’—it has been claimed that the gravitational pull of the moon (which was stronger when it was much closer several billion years ago) could have concentrated uranium at the high-water mark on beaches. The energy from the radiation might have helped generate organic molecules serving as a catalyst to early life. We think this theory makes panspermia sound quite normal!
The smart money is probably on panspermia or deep-sea vents, but the only thing we can say for sure is that ‘the truth is out there’. [geoip-content not_country=”CA”]
Discover the fascinating animal life that roam the ocean floor and uncover their secrets to the origin of all life on this planet in Life 2000 Metres Under the Sea, now streaming on Love Nature. [/geoip-content]