How life got started on Earth is still a big problem for scientists. The story goes something like this: "Well, there was this primordial soup of amino acids and stuff, then maybe there was some lightning, or something, and then ::mumble, mumble:: and then we had life." Awkward! But that awkwardness may be over: Research on the Murchison meteor, which landed in Australia in 1969, has found that the rock carried the building blocks of DNA on board. The finding puts panspermia firmly in the spotlight as a possible origin for life on Earth, and makes a lot more sense than that old tale of thunderstorms and arm-waving.
Panspermia theories often argue that Martian mircobes hitched a ride on an Earth-bound meteor, then thrived and evolved into the life we see here on Earth. But the new findings from researchers at Imperial College London suggest the building blocks of life rather than life itself arrived from outer space. They figure that since the Murchison meteor fell to Earth bringing the molecules uracial and xanthine — precursors to DNA — there must have been a lot of this stuff pelting the planet billions of years ago.
Early life may have needed the space-born material to get started, or it could've incorporated the meteorite bits because they conferred some kind of evolutionary advantage:
Lead author Dr Zita Martins, of the Department of Earth Science and Engineering at Imperial College London, says that the research may provide another piece of evidence explaining the evolution of early life. She says:
"We believe early life may have adopted nucleobases from meteoritic fragments for use in genetic coding which enabled them to pass on their successful features to subsequent generations."
Between 3.8 to 4.5 billion years ago large numbers of rocks similar to the Murchison meteorite rained down on Earth at the time when primitive life was forming. The heavy bombardment would have dropped large amounts of meteorite material to the surface on planets like Earth and Mars.
Either way, it looks like we're made of space stuff.
Source: Imperial College London