Life on Mars? Oldest fossil ever found suggests 'yes'...

The discovery is the strongest evidence yet that similar organisms could also have evolved on Mars. Photo: PA

It's life, but not as we know it. The oldest fossil ever discovered on Earth shows that organisms were thriving 4.2 billion years ago, hundreds of millions of years earlier than previously thought.

The microscopic bacteria, which were smaller than the width of a human hair, were found in rock formations in Quebec, Canada, but would have lived in hot vents in the 60C oceans which covered the early planet.

The discovery is the strongest evidence yet that similar organisms could also have evolved on Mars, which at the time still had oceans and an atmosphere, and was being bombarded by comets which probably brought the building blocks of life to Earth. The team who made the finding at University College London believe that looking for similar fossils on the Red Planet is the best chance of finding evidence of alien life.

"Early Mars and early Earth are very similar places, so we may expect to find life on both planets at this time," said doctoral student Matthew Dodd, the lead author of the study which was co-funded by Nasa.

"We know that life managed to get a foothold and evolve rapidly on Earth. So if we have life evolving in hydrothermal vent systems maybe even 4.2 billion years ago when both planets had liquid water on their surface, then we would expect both planets to develop early life.

"If we do future sample returns from Mars and look at similarly old rocks and we don't find evidence of life then this certainly may point to the fact that Earth might have been a very special exception, and life may just have arisen on Earth."

Undated handout photo issued by UCL of layer-deflecting bright red concretion of haematitic chert (an iron-rich and silica-rich rock), which contains tubular and filamentous microfossils, discovered in a rock formation in Quebec, Canada, known as the Nuvvuagittuq Supracrustal Belt (NSB). Remains of microbial bugs thought to be the oldest known on Earth have been unearthed by British scientists. Photo: Dominic Papineau/PA Wire

Prior to this discovery, the oldest microfossils reported were found in Australia and dated at 3.4 billion years ago, leading scientists to speculate that life probably started around 3.7 billion years ago. But the new finding suggests life could have formed as early as 4.5 billion years ago, 100 million years after Earth formed.

The tiny lifeforms were discovered in the Nuvvuagittuq Supracrustal Belt in Quebec, which contains some of the oldest sedimentary rocks in the world, dating back to 4.3 billion years ago. (© Daily Telegraph London)

Telegraph.co.uk