We may all be Martians, says geochemist

It's likely that life came to Earth on a Martian meteorite; conditions suitable for the origin of life may still exist on Mars
August 30, 2013
mars_nasa_image

(Credit: NASA)

New evidence has emerged that supports the long-debated theory that life on Earth may have started on Mars.

Speaking at the at the annual Goldschmidt conference on Thursday, Professor Steven Benner from The Westheimer Institute for Science and Technology told geochemists that an oxidized mineral form of the element molybdenum, which may have been crucial to the origin of life, could only have been available on the surface of Mars and not on Earth.

“In addition, recent studies show that these conditions, suitable for the origin of life, may still exist on Mars,” he added.

“It’s only when molybdenum becomes highly oxidized that it is able to influence how early life formed,” said Benner. “This form of molybdenum couldn’t have been available on Earth at the time life first began, because three billion years ago, the surface of the Earth had very little oxygen, but Mars did. It’s yet another piece of evidence which makes it more likely life came to Earth on a Martian meteorite, rather than starting on this planet.”

Paradoxes

Benner tackled two of the four paradoxes that make it difficult for scientists to understand how life could have started on Earth.

The Tar Paradox: organic molecules, given energy and left to themselves, devolve into complex mixtures, “asphalts,” better suited for paving roads than supporting Darwinian evolution. Any scenario for origins requires a way to allow organic material to escape this devolution into a Darwinian existence, where replication with imperfections, where the imperfections are themselves heritable, allows natural selection to avoid a tarry fate.

The Water Paradox: water is commonly believed to be essential for life. So are biopolymers, like RNA, DNA, and proteins. However, the biopolymers that we know find water corrosive. Any scenario for origins must manage the apparent need of life for a substance (water) this is inherently toxic to life.

“The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock,” says Professor Benner. “It’s lucky that we ended up here nevertheless, as certainly Earth has been the better of the two planets for sustaining life. If our hypothetical Martian ancestors had remained on Mars, there might not have been a story to tell.”