Russian biologist A. P. Oparin and Scottish biologist J. B. S. Haldane both proposed an early reducing atmosphere on Earth consisting of hydrogen rich molecules such as hydrogen gas, methane, ammonia, along with nitrogen, carbon dioxide, and water vapor. The scientists suspected that these gases were either left over from the solar nebula or belched into the atmosphere from geologic/volcanic processes. Ultra violet light from the early Sun and electrical activity (lightning) would ‘cook’ such an atmosphere into a rich brew of energy rich biochemicals including amino acids and other compounds.
Oparian and Haldane also hypothesized that the earliest lifeforms would have been anaerobic cells, living on available biochemicals in the shallow waters in the seas and perhaps in the soils. Anaerobic organisms do not need sunlight, nor do they need oxygen, in fact they do not need atmosphere at all. Anaerobic bacteria exist today and include among their number species that live miles below the Earth’s surface as well as at the bottom of the sea near or in hydrothermal vents. Some of these organisms have not seen sunlight or free atmosphere for billions of years. Which leads astrobiologists to explore extreme environments on Earth in order to gain a deeper understanding of how life may take root on other worlds.
In this episode of ‘How Do You KNOW?’ Dr. Barth examines the origins and extremes of life as we know it, why we are searching for life on Mars and other worlds, and why once a planet holds life, that sterilizing that planet by any means short of a stellar catastrophe is virtually impossible.
Download the free study guide ‘The Origin of Life’ and get the free e-book ‘Astronomy For Educators’ to learn more.
- Return to the How Do You KNOW? index of programs.
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