SCOTTISH SCIENTISTS have concluded that the evolution of complex life forms began 400 million years earlier than previously believed.

Until now, it was thought an important change in the earth’s oxygen levels occured 800 million years ago, but the researchers found that this actually took place 1.2 billion years ago.

This increase in oxygen levels helped the development of more complex cells, such as the ones humans eventually emerged from.

The team of geologists analysed the chemical composition of rocks near Lochinver and found that an important bacterial group existed within the rocks 1.2 billion years ago.

Adrian Boyce from the Scottish Universities Environmental Research Centre in Glasgow said:

Our geochemical analyses have provided a clear signal that levels of oxygen in the atmosphere had increased to levels critical to the evolution of complex life – from which we ourselves emerge – much earlier than has been previously proven to date. This opens the door to a new understanding of the evolution of our planet’s atmosphere and the life it sustains.

The researchers’ paper was published in the science journal Nature.