Back in the 1970s I first encountered the results of an unusual experiment conducted in 1953 by an American chemist named Stanley Miller. In it, he combined certain gasses that scientists thought were probably in the atmosphere on the earth prior to the beginning of life. He added an electric spark to simulate lightning and left the mixture to stew. After a while, the mixture started turning into a brown goo. He tested it and found five amino acids: the building blocks of proteins. This was a pretty astounding result and fueled research into how life on the earth could have come to be.
After Miller's death in 2007, scientists found a box of samples from this early experiment and others that Miller conducted along the same lines. They decided to retest the samples with more modern and sensitive equipment. Where Miller's original sample contained five amino acids, a follow-up experiment contained twenty-three -- further illustrating how life could have evolved on the earth.
Other experiments in the ensuing decades, including testing on meteorites, have shown similar results: amino acids could have formed on planetary bodies other than the earth.
You can read more about these amazing new findings here.