When the composition of the Earth's atmosphere changes, the evolution of animals can change.
The most important event in the history of life on Earth is often thought to have originated from the Cambrian explosion, from about 541 to 516 million years ago, life began to diversify.
Recently, an international team of researchers has suggested that increasing oxygen levels somehow creates an explosion and disrupts our planet's animal system, like the conductor of a live symphony.
For the first time, the study linked the rapid emergence of animal life in the Cambrian explosion with an increase in atmospheric oxygen levels, and showed the mass extinction events associated with slumping. corresponding oxygen reduction.
"Complex creatures that appear in the Cambrian explosion are precursors to many modern animals that we see today," explained the University of Leeds chemist Tianchen He.
But since there is no direct record of atmospheric oxygen levels at this time, it is difficult to determine which factors may have triggered this important point in evolution.
The answer is given in Siberia - an area known as the Siberian platform , which used to be a shallow sea and is home to half of the fossil species found to exist in the Cambrian period.
Analyzing ancient limestone samples from the two rivers in this area, researchers were able to create a model to compare carbon and sulfur cycles, estimated oxygen concentrations, and animal diversity. from more than half a billion years ago.
The finding shows that during high oxygen periods, the shallow ocean experiences pulses of animal diversification, giving a possible explanation for the "step by step " of the Cambrian explosion.
"In modern and ancient oceans, good oxygen-rich water is often associated with greater body size in animals, greater diversity, advanced bone structure, increased mobility and meat consumption." , the authors write.
On the other hand, during low oxygen, for example in Cambrian soon researchers have noted a "long pause" in diversification, lasting more than 20 million years and causing many extinctions.
The origin of the Cambrian explosion has confounded scientists for many years and the role of oxygen is being debated. These new findings strongly support the most popular science story, showing that new animal body structures and lifestyles are associated with much higher oxygen demand, and this can play a role. important in adjusting the life model we see today.
"This is the first study to show clearly that our earliest animal ancestors underwent a series of evolutionary and congested radiation caused by extreme changes in atmospheric oxygen concentrations , " Researcher Graham Shields from University College London said.