Primitive life existed on earth over 2 billion years ago, researchers say

French researchers have discovered that life was already moving on our planet earlier than first thought - now thought to be 2.1 billion years ago.

Previously, early life forms were said to date back to 1.5 billion years.

The oldest traces of motility (the ability for an organism to move independently using metabolic energy) were found in well-preserved fossils in the Franceville Basin, Gabon.

Researchers said they found a sophisticated multicellular organism that would have been able to move through mud, well before there were animals roaming the planet, according to an article published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Abderrazak El Albani, a professor at the University of Poitiers, said: "The basin at Gabon is a wonderful place because we can have an incredible window on the history of life on earth.

"It's what will inform us about our origins.

"From the passage from a single cell to multi-cell organisms that will prepare the ground for the future.

"The evidence is solid with several techniques that have shown this movement."

X-ray computed microtomography showed thin, tube-like structures formed in shale, revealing the footprints of worm-like or slug-like creatures that could have been able to make a "wriggle" motion.

The Science Daily Journa l reported that it is conceivable the organisms moved to search for nutrients.