Complex life first began to form more than 650 million years ago during a global ice age that scientists refer to as “Snowball Earth,” according to new evidence. Researchers believe that glaciers covered just about every inch of the planet and reduced mountain ranges to rubble, allowing trapped nutrients to escape and fueling the rise of animals and the planet we know today.

Once that happened, nutrients were washed into oceans, which led to the development of algae, which of course marked the start of complex cology and gradual evolution of animal species, new research claims. And if it hadn’t have happened, mankind would have never existed, according to a statement from Australian National University.

Researchers say they found the answer by examining ancient sedimentary rocks in central Australia. They crushed the rocks to powder and extracted molecules from ancient organisms, indicating that things really began to develop in earnest 650 million years ago.

“We crushed these rocks to powder and extracted molecules of ancient organisms from them,” said Dr Jochen Brocks from the ANU Research School of Earth Sciences.

“These molecules tell us that it really became interesting 650 million years ago. It was a revolution of ecosystems, it was the rise of algae.”