Changes in solar energy fuelled high speed evolutionary changes, study suggests | Science
J.Just over 500 million years ago, life on Earth accelerated from simple single-celled organisms to sophisticated multicellular life forms. The Cambrian explosion produced a series of weird and wonderful new inhabitants, such as the five-eyed opabinia and the wiwaxia spiny slug. Pulses of oxygen in the atmosphere and ocean are thought to have fueled this diversification, but until now it was unclear what was causing the oxygen fluctuations. A study now suggests that changes in Earth’s orbit could be behind these evolutionary impulses.
The researchers used a climate and biogeochemical model and studied how periodic changes in Earth’s orbit affected the amount of solar energy reaching Earth. They found that changes in solar energy every two to three million years followed the ups and downs in observed oxygen levels.
Writing in Geophysical Research Letters, the researchers suggest that changes in solar energy caused climate shifts that altered the extent of weathering of land surfaces – particularly at high latitudes – with periods of rapid weathering releasing bursts of nutrients into the oceans, which drove photosynthesis and increased oxygen levels, fueling high-speed evolutionary changes.
Similar orbital changes have occurred in other eras, but only the Cambrian period had all the necessary ingredients to enable this exceptional evolutionary explosion.
