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 Life evolved on Earth more than four billion years ago, during the time known as the Precambrian. The first land and seas formed and the first single-celled organisms appeared in the oceans.
Some of these organisms transformed Earth by creating an oxygen-rich environment. Eventually, organisms that could reproduce sexually evolved and were later followed by the first animals.
To learn more about the origins of life on Earth, select from the following:
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Basic Overview
Get the full story on how life may have begun here on Earth and learn more about the first single-celled organisms and animals that evolved during the Precambrian.
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Image Gallery
Take a look at amazing images of the first life forms, and view meteorites and thermal vents that may have played a role in the origins of life.
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Evolutionary Essentials
Find out more about photosynthesis, sexual reproduction, and natural selection—key elements in evolutionary history during the Precambrian that forever changed our world.
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Featured Scientists
View video interviews and meet scientists from The Field Museum and the University of Chicago who study the origins of life.
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Continue to Basic Overview. >>
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