Hexbyte Glen Cove Study reveals more hostile conditions on Earth as life evolved 

Hexbyte Glen Cove

Graphic showing how UV radiation on Earth has changed over the last 2.4 billion years. Credit: Please credit: Gregory Cooke/ Royal Society Open Science

During long portions of the past 2.4 billion years, the Earth may have been more  inhospitable to life than scientists previously thought, according to new computer simulations.

Using a state-of-the-art climate model, researchers now believe the level of ultraviolet (UV) reaching the Earth’s surface could have been underestimated, with UV levels being up to ten times higher.

UV radiation is emitted by the sun and can damage and destroy biologically important molecules such as proteins.

The last 2.4 billion years represents an important chapter in the development of the biosphere. Oxygen levels rose from almost zero to significant amounts in the atmosphere, with concentrations fluctuating but eventually reaching modern day concentrations approximately 400 million years ago.

During this time, more complex multicellular organisms and animals began to colonize land.

Gregory Cooke, a Ph.D. researcher at the University of Leeds who led the study, said the findings raise new questions about the evolutionary impact of UV radiation as many forms of life are known to be negatively affected by intense doses of UV radiation.

He said: “We know that UV radiation can have disastrous effects if life is exposed to too much. For example, it can cause skin cancer in humans. Some organisms have effective defense mechanisms, and many can repair some of the damage UV radiation causes.

“Whilst elevated amounts of UV radiation would not prevent life’s emergence or evolution, it could have acted as a selection pressure, with organisms better able to cope with greater amounts of UV radiation receiving an advantage.”

The research “A revised lower estimate of ozone columns during Earth’s oxygenated history” is published today in the scientific journal Royal Society Open Science.

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