Their first clues arose from the fact that it is estimated that oxygen levels were relatively low in the environment during the Neoproterozoic period – when the first multicellular life began to emerge.

At the same time, there was a dramatic increase in the availability of copper during this period. This occurrence combined with the crucial role that copper plays in the creation of proteins, allowed them to reach their conclusion regarding the importance of the mineral.

“Oxygen was actually toxic to earlier primitive life, but copper gave animals the means to cope with it”

Copper was particularly key in the development of proteins that helped primitive jellyfish and sea sponges develop respiratory systems.

“Oxygen was actually toxic to earlier primitive life, but copper gave animals the means to cope with it and use it to their advantage – it was a clever bit of evolution,” John Parnell, lead author of the study, said in a media statement. “Our research shows that across the planet, magmas from deep in the Earth brought copper-bearing volcanic rocks to the surface about 800 million years ago.”

Parnell explained that animals used copper in several ways, but two critical functions of the metal gave animals the strength to support themselves, and the ability to breathe oxygen from the air by making compounds called copper proteins, which are essential to the way they live.

“Oxygen in the air had the double role of weathering rocks to provide copper, and of letting animals breathe, which they could do using their copper proteins,” he said.

In the view of co-author Adrian Boyce, it is no coincidence that some of the biggest copper ore deposits in the world, which are located in Africa, formed just as the first animals were starting to emerge.

“Life and rocks were in harmony,” Boyce said.