Slight increase in oxygen levels on Earth could have sparked huge evolutionary leapNew research challenges decades-old assumptions on the drivers of the Camrbian explosion.
The actual evidence for the increase in ocean oxygen levels is sparse, scattered, and at times contradictory.
A slight increase in oxygen levelsThe new research indicates that a slight increase in oxygen levels in the shallow portions of the oceans were sufficient to drive the diversification event.
The researchers used statistical and machine learning techniques to estimate historical oxygen levels using oceanographic data.
Lead author of the paper, Richard Stockey says, “The Cambrian explosion was a remarkable period of rapid diversification of life on Earth.
Slight increase in oxygen levels on Earth could have sparked huge evolutionary leap
New research challenges decades-old assumptions on the drivers of the Camrbian explosion.
Fossil of a Cambrian sea creatuer, Opabinia regalis. (Image Credit: University of Southampton).
New Delhi: New research from an international consortium of scientists from over 50 institutions around the world challenges the conventional explanation of the Cambrian explosion, a dramatic diversification of life that occurred around 540 million years ago. The conventional belief, that has persisted for decades, was that there was a sudden spike in atmospheric oxygen, that brough oxygen in the oceans close to modern levels, driving the rapid evolution marked in the fossil record by the emergence of a variety of body plans and sensory organs.
The actual evidence for the increase in ocean oxygen levels is sparse, scattered, and at times contradictory. The researchers discovered that oxygen levels in the deep oceans did not approach that of modern levels till about 140 million after the Cambrian explosion, or about 400 million years ago, around the same time that large forests began to appear on land. During the time of the Cambrian explosion, most of the animals lived in shallow waters, and the churning of the oceans by winds and waves could have oxygenated the shallow waters while the deep oceans remained unchanged.
A slight increase in oxygen levels
The new research indicates that a slight increase in oxygen levels in the shallow portions of the oceans were sufficient to drive the diversification event. The researchers used statistical and machine learning techniques to estimate historical oxygen levels using oceanographic data. The researchers discovered that the data indicating whole ocean oxygenation occurs during the Devonian period, 140 million years after the Cambrian Explosion. The analysis allows researchers to better understand other drivers of evolution apart from oxygenation, including temperature and food supply.
A paper describing the findings has been published in Nature Geoscience. Lead author of the paper, Richard Stockey says, “The Cambrian explosion was a remarkable period of rapid diversification of life on Earth. Previously life consisted of single cell and small multicellular organisms. Then, within 20 or 30 million years, a geological blink, we see a variety of strange and complex creatures emerge with new body plans and features like mineralized shells, grasping appendages, and complex sensory organs like eyes.”. Leader of the consortium, Erik Sperling says, “Cambrian animals likely did not require as much oxygen as scientists used to believe. We found minor increases in oxygenation that are at the correct magnitude to drive big changes in ecology.”
