Home Science ‘Sunscreen’ in ancient pollen ‘points to mass extinction attributable to UV radiation’

‘Sunscreen’ in ancient pollen ‘points to mass extinction attributable to UV radiation’


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Sunscreen-like chemicals present in ancient pollen suggest ultraviolet radiation played an element in one among the largest mass extinctions that took place 250 million years ago, scientists have said.

A team of experts from the UK, Germany and China analysed ancient pollen grains – about half the width of a human hair – preserved in rocks recovered from Tibet.

Inside these pollens they found compounds produced by 250-million-year-old plants to guard themselves from harmful ultraviolet (UV-B) radiation.

The experts said their findings, published within the journal Science Advances, add further evidence to the idea that a “pulse of UV-B played a very important part at the top Permian mass extinction event”.

Professor Barry Lomax, from the University of Nottingham, said: “Plants require sunlight for photosynthesis but must protect themselves and particularly their pollen against the harmful effects of UV-B radiation.

“To accomplish that, plants load the outer partitions of pollen grains with compounds that function like sunscreen to guard the vulnerable cells to make sure successful reproduction.”

About 250 million years ago, at the top of the Permian period, something killed greater than 80% of the planet’s species, in what’s regarded as essentially the most severe of the large five mass extinction events.

The event is believed to have been triggered by a large volcanic eruption, in regards to the size of modern-day Siberia, which then led to large amounts of carbon being pumped into the atmosphere, making a greenhouse effect.

The sudden warming process affected the ozone layer, causing it to weaken, and exposing plants and animals to the harmful effects of UV-B radiation.

The scientists said that other discoveries of malformed spores and pollen grains from this time period also add further evidence of the destruction attributable to UV irradiation.

Dr Wes Fraser, from Oxford Brookes University, said: “Volcanism on such a cataclysmic scale impacts on all facets of the Earth system, from direct chemical changes within the atmosphere through changes in carbon sequestration rates, to reducing volume of nutritious food sources available for animals.”



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