Ever wonder how life started on Earth?
For a long time, scientists thought that more oxygen in the oceans helped kick-start the development of more complex life forms.
However, new research is turning that idea on its head!
Hundreds of millions of years ago, our oceans began to fill with strange multicellular creatures, such as sea sponges.
This time is known as the Avalon explosion. It was a big shift because before then, simple single-celled life forms like amoebas, algae, and bacteria had been the main inhabitants of our planet for over 2 billion years.
For about 70 years, scientists believed that an increase in oxygen levels in the ocean caused this explosion of new, more advanced creatures. But, a new study says this isn’t true.
The researchers studied the chemistry of ancient rocks from a mountain range in Oman to work out how much oxygen was in the oceans when these multicellular organisms started to appear.
Surprisingly, they found that the oxygen levels hadn’t gone up.
In fact, oxygen levels were 5-10 times lower than they are today, which is roughly the same amount of oxygen you’d find at twice the height of Mount Everest!
Christian J. Bjerrum, a professor at the University of Copenhagen who has been studying the origin of life for the past 20 years, said that there was even a slight decrease in oxygen when these more advanced life forms began to take over.
This new finding changes our understanding of how life developed on Earth. According to Bjerrum, it means we have to reconsider a lot of things we learned in school about the origin of life.
Even textbooks might need to be updated!
But there’s still a lot we don’t know, and these findings are bound to stir up some controversy. Bjerrum hopes other scientists around the world will take a look at their old results and data with this new perspective in mind.
To come to their conclusions, the researchers analyzed rock samples from mountains in Oman, which used to be at the bottom of the sea during the Avalon explosion. They also confirmed their findings with fossils from two other mountain ranges, one in Canada and another in China.
So, if an increase in oxygen didn’t cause the explosion of life, what did? Bjerrum suggests it might have been the exact opposite – the low oxygen levels.
He says that low oxygen might have protected the stem cells of these early multicellular organisms, allowing them to develop slowly and sustainably. This idea is similar to how low oxygen levels help control stem cells in humans and other animals.
Researchers from the Woods Hole Oceanographic Institute, the University of Southern Denmark, Lund University, and the University of Copenhagen also contributed to this study.
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Source: University of Copenhagen.
