Life on Earth? It just snowballed

♦ The mystery of how animals were able to evolve 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 has existed for billions of years, before 650million years ago it was largely just viruses, bacteria and early multi-cellular jellylike creatures.

Now scientists at the Australian National University have discovered that freezing conditions which turned Earth into a giant snowball around 700million 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.

The team made the discovery after looking at rocks in Central Australia dating back 650 million years, which were found to be full of molecules from ancient algae. Associate professor Jochen Brocks, the lead researcher, said: “Before all of this happened, there was a dramatic event 50million years earlier called Snowball Earth.

“The Earth was frozen over for 50million 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, 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. The research is published in Nature, and will be presented at the Goldschmidt Conference in Paris.