Conventional theory, based on fossil evidence, suggests that this spread took place by land, via the Levant.
But any fossil evidence of the microbes themselves has long since disappeared: "They're good and cooked, " Professor Muelenbachs explained.
BBC: NEWS | Science/Nature | Early life thrived in lava flows
Fossil evidence suggests some populations could have been around tens of thousands of years ago, long before the emergence of agriculture.
New fossil evidence seems to confirm that a key ancestor of ours could walk upright consistently - one of the major advances in human evolution.
The best fossil and DNA evidence today indicates it was a rare Neanderthal who lived past the ripe old age of 35.
The techniques needed to extract fossil and climatic evidence from this lake bed, and to search for life forms that have adapted to survive in such hostile conditions, would also work on Mars so it is an ideal location to test robots and even to train would-be astronauts.
They also encourage teachers to discuss with their students such things as gaps in the fossil record, molecular evidence, that they say raises questions about the theory of evolution.
Some claimed it contained fossil like features and evidence of ancient microscopic life on the Red Planet, others dismissed the claims, saying it had been contaminated since it had been on earth.
For instance, the evolutionary theory bases its evidence on the fossil record.
Researchers from Johns Hopkins and the University of California at Berkeley found evidence in data collected from 176 thriving plant species that fossil plants can help scientists determine sources of carbon in the atmosphere hundreds of millions of years ago.
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