Meet the ancestors: Earliest evidence of life suggests humans descended from sponges 635million years ago

By Daily Mail Reporter
Last updated at 11:01 AM on 05th February 2009

Chemical traces left behind in 635 million-year-old rocks are the earliest evidence ever found of animal life on Earth, researchers said today.

An analysis of molecules in the ancient stones from Oman revealed a form of cholesterol only produced by sponges.

The findings, published just days before the 200th birthday of naturalist Charles Darwin, are also proof that simple organisms MUST must have existed before evolving into more complex creatures, the scientists said.

'Basically we have found a thread of that evidence that he predicted should be there,' said study leader Roger Summons, a geobiologist at the Massachusetts Institute of Technology.

'There is a great wealth of evidence these sponges were the first multi-cellular organisms to exist.'

It suggests the creatures existed before a monstrous ice age that occurred around 630 million years ago. Many scientists believe the frozen periods spurred the development of complex forms of life, Professor Summons said.

These simple forms of animal life came about 200 million years before land plants appeared on Earth, he added.

The first single cell bacteria and other similar forms of life appeared around two-and-a-half billion years ago.

The oldest visible fossils of animals found in rocks are 580 million years old.

However, the findings from the paper published in the journal Nature show that looking at molecular evidence is key to better understanding evolution, Professor Summons added.