Rise of animals 650 million years ago sparked by boom of sea algae after 'Snowball Earth' melted

The mystery of how animals evolved on Earth has been uncovered by scientists who found that crumbling mountains fed the seas with nutrients, sparking a surge of complex life.

Although simple life on our planet existed for billions of years, before 650 million years ago it was largely just viruses, bacteria and early multi-cellular jelly-like creatures.

Now scientists at the Australian National University have discovered that freezing conditions which turned Earth in a giant snowball at around 700 million years ago also pulverised mountain ranges.

When the glaciers finally melted 50 million years later, the rich mountain ‘dust’ was mixed into the newly formed seas and oceans where it allowed blue algae to thrive, and set in motion an evolutionary process which would eventually lead to animals and humans.

The team made the discovery after looking at rocks in Central Australia dating back to 650 million years ago, which were found to be full of molecules from ancient algae.

Lead researcher Associate Professor Jochen Brock said: “Before all of this happened, there was a dramatic event 50 million years earlier called Snowball Earth.

“The Earth was frozen over for 50 million years. Huge glaciers ground entire mountain ranges to powder that released nutrients, and when the snow melted during an extreme global heating event rivers washed torrents of nutrients into the ocean.”

Dr Brocks said the extremely high levels of nutrients in the ocean, and cooling of global temperatures to more hospitable levels, created the perfect conditions for the rapid spread of algae.

It was the transition from oceans being dominated by bacteria to a world inhabited by more complex life, he said.

“These large and nutritious organisms at the base of the food web provided the burst of energy required for the evolution of complex ecosystems, where increasingly large and complex animals, including humans, could thrive on Earth,” Dr Brocks said.

The research is published in Nature, and the findings will be presented at the Goldschmidt Conference in Paris, France, this week.

Co-lead researcher Dr Amber Jarrett of ANU, who studied the ancient sedimentary rocks from just after the melting of Snowball Earth said: “In these rocks we discovered striking signals of molecular fossils.

“We immediately knew that we had made a ground-breaking discovery that snowball Earth was directly involved in the evolution of large and complex life.”