The 'explosion' of animal life on Earth may have taken place after slow rise of oxygen, revealed a new study. The UCL-led study suggested that it took 100 million years for oxygen levels in the oceans and atmosphere to increase to the level that allowed the explosion of animal life on Earth about 600 million years ago.
Before now it was not known how quickly Earth's oceans and atmosphere became oxygenated and if animal life expanded before or after oxygen levels rose. The new study shows the increase began significantly earlier than previously thought and occurred in fits and starts spread over a vast period. It is therefore likely that early animal evolution was kick-started by increased amounts of oxygen, rather than a change in animal behavior leading to oxygenation.
‘Early animal evolution was probably kick-started by increased amounts of oxygen, rather than a change in animal behavior leading to oxygenation.’
Lead researcher Philip Pogge von Strandmann (UCL Earth Sciences) said, "We took a new approach by using selenium isotope tracers to analyze marine shales, which gave them more information about the gradual changes in oxygen levels than is possible using the more conventional techniques used previously. We were surprised to see how long it took Earth to produce oxygen and their findings dispel theories that it was a quick process caused by a change in animal behavior."
The study appears in Nature Communications.