Public Release:  Lots of oxygen does not necessarily lead to the evolution of advanced life

University of Southern Denmark


IMAGE: According to Emma Hammarlund these 2-billion-year-old fossils represent an early life form that experimented with evolving into some kind of multicellular lifeform, but did not succeed. view more

Credit: Abder El Albani

Any textbook will tell you that oxygen is essential for advanced life to evolve. For example, ancient dinosaurs and modern large-brained mammals need a lot of oxygen to keep their large and sophisticated organisms running. But why did life not explode when oxygen levels rose dramatically 2.1 billion years ago? This is the big question after a Danish/Swedish/French research team, led by University of Southern Denmark, has shown that the oxygen content 2.1 billion years ago was probably the same as when life exploded 500 million years ago.

Oxygen and advanced life are inextricably linked. Some simple organisms like bacteria can survive without oxygen, but all higher organisms need oxygen and the Earth's biology would probably be a poor sight, if the atmosphere did not contain the 21 pct. oxygen, which is essential for eg the human brain to function.

The development of life exploded around 542 million years ago during the so-called Cambrian explosion, where oxygen levels rose to up to 10 pct. Before that life consisted of small and simple, typically single-celled life forms, and science has long thought that there was not enough oxygen for it to evolve into something bigger.

But now a Danish/Swedish/French research team shows that there was actually plenty of oxygen long before the Cambrian explosion. The team consists of professor Donald Canfield and postdoc Emma Hammarlund from the Nordic Center for Earth Evolution (NordCEE) at University of Southern Denmark, colleagues from the National Museum in Sweden and colleagues from the following French institutions: Université de Poitiers, the Centre National de la Recherche Scientifique, Institut Francais de la Recherche pour l' Exploitation de la Mer, Centre de Brest and the Université de Rennes in France.





"Currently we consider it more likely that any great evolution just did not occur then. But why not, since there was plenty of oxygen?", speculates Emma Hammarlund, and tries to answer:





How oxygen contents rose and fell 2 billion years ago:




Oxygen dynamics in the aftermath of the Great Oxidation of Earth's atmosphere. doi: 10.1073/pnas.1315570110. PNAS September 30, 2013


contact Emma Hammarlund:

This press release was written by press officer Birgitte Svennevig
