Where Did Life on Earth Originate?
Life on Earth has existed for billions of years, but did it all start here? Hundreds of millions of years before there were any fish or plants as we know them, single-cell organisms occupied the oceans of our world.
All of the necessary building blocks have existed on Earth nearly from the start. Early bombardment during the formation of the Solar System, however, made conditions far from safe for life.
But the bombardment of Earth by meteors may have started it all off. One theory states that simple hydrocarbon compounds riding on meteoroids crashed into Earth giving rise to more complex chemicals—a step closer to life itself. Experiments in the laboratory have shown that such chemicals indeed increase in complexity after hypervelocity impact. An alternate version states that the chemicals resided on Earth and simple meteor collision added the needed energy to transform the chemicals.
In one series of Japanese experiments, a pellet made of iron and carbon was shot at a stainless steel container at 4,500 miles per hour, generating temperatures of about 5,000 degrees Fahrenheit (2,800°C). The container held a solution of ammonia and water. This "shock" impact produced amines, fatty acids and glycine (an amino acid). These are important components of life.
But there is another theory that life originated elsewhere and was carried to Earth.