In 1877, the Italian astronomer Giovani Schiaparelli conducted an exhaustive and detailed observation of the surface of Mars.
He described huge streaks across the surface, which he called canali or "channels." In English, the word was incorrectly translated as "canals," and compared to the recently-built Suez Canal. This set off what would be a long and unabated fixation on the possibility of life on the Red Planet.
NASA's recent discovery of water on Mars has rekindled hopes that we may yet find neighbors in our solar system. But other things we've learned about Mars — and particularly ancient Mars — give us clues suggesting we should consider the possibility that we have already discovered Martian life. They might also hold important implications for the most enduring mystery in science, the origin of life.
In recent years, the idea that life on Earth may have first arisen elsewhere — before migrating to our planet — has gained some traction. The theory is called "panspermia," Greek for "life everywhere," the name given it by the ancient philosopher Anaxagoras. It became particularly popular during the 19th century, partly because it explained some gaps in Darwin's concept of evolution. The evolution of complex creatures, such as human beings, through natural selection was thought to require at least hundreds of millions of years. Such a timeframe was difficult to reconcile with 19th century estimates of the Earth's age, something usually then measured in the tens of millions. Panspermia solved that problem — and two of the most accomplished scientists of the age became key proponents, the Swedish chemist Svante Arrhenius, director of the Nobel Institute, and Lord Kelvin, who was instrumental in formulating the theory of thermodynamics.
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