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Life on Earth began more than 3 billion years ago, evolving from the most basic of microbes into a dazzling array of complexity over time. But how did the first organisms on the only known home to life in the universe develop from the primordial soup?
One theory involved a "shocking" start. Another idea is utterly chilling. And one theory is out of this world!
Inside you'll learn just how mysterious this all is, as we reveal the different scientific theories on the origins of life on Earth.
It started with an electric sparkSlide 2 of 15
It started with an electric spark
Lightning may have provided the spark needed for life to begin.
Electric sparks can generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia and hydrogen, as was shown in the famous Miller-Urey experiment reported in 1953, suggesting that lightning might have helped create the key building blocks of life on Earth in its early days. Over millions of years, larger and more complex molecules could form. Although research since then has revealed the early atmosphere of Earth was actually hydrogen-poor, scientists have suggested that volcanic clouds in the early atmosphere might have held methane, ammonia and hydrogen and been filled with lightning as well.
Or could simple clay have fueled life’s beginning? Read on to find out.Slide 3 of 15
Molecules of life met on claySlide 4 of 15
Molecules of life met on clay
The first molecules of life might have met on clay, according to an idea elaborated by organic chemist Alexander Graham Cairns-Smith at the University of Glasgow in Scotland. These surfaces might not only have concentrated these organic compounds together, but also helped organize them into patterns much like our genes do now.
The main role of DNA is to store information on how other molecules should be arranged. Genetic sequences in DNA are essentially instructions on how amino acids should be arranged in proteins. Cairns-Smith suggests that mineral crystals in clay could have arranged organic molecules into organized patterns. After a while, organic molecules took over this job and organized themselves.
Or maybe life began at the bottom of the sea. Keep going to learn how.Slide 5 of 15
Life began at deep-sea ventsSlide 6 of 15
Life began at deep-sea vents
The deep-sea vent theory suggests that life may have begun at submarine hydrothermal vents spewing key hydrogen-rich molecules. Their rocky nooks could then have concentrated these molecules together and provided mineral catalysts for critical reactions. Even now, these vents, rich in chemical and thermal energy, sustain vibrant ecosystems.
The next idea is a chilling thought. Read on!Slide 7 of 15
Life had a chilly startSlide 8 of 15