Science Quarks and Quirks: Our Parents are Aliens?

Panspermia is the idea that life on a planet can be established by distribution from one celestial body to another, via natural means. The original concept was proposed in 1865 by Hermann Eberhard Friedrich Richter and over the years it has gained remarkable popularity (if not solid evidence). Scientists are researching the potential for microbes to survive the harsh environments of space, atmospheric entry and the impact on Earth necessary for the hypothesis to be true. This may all sound suspiciously like Ridley Scott’s ‘Prometheus’ but I can assure you that the science is far more interesting than any mediocre film could convey.

Past research has suggested that DNA is highly vulnerable to destruction by cosmic radiation, but another molecule call

ed RNA may have had the potential to kick-start life on Earth. This is because RNA has the ability to reproduce without help (eg. enzymes). It can, on its own, create secondary and tertiary structures which could catalyse the production of other RNA molecules. If life on Earth started off with an ‘RNA world’ and there was an eventual transition to DNA, then RNA-viruses may have taken a role- if the Panspermia theory is to be believed. However, the huge difficulty in this concept is that viruses need a host to survive (a factor sadly lacking when forming new life on a planet) and unless evidence suggests ancient viruses could live without this basic requirement, the hypothesis falls flat.

While the Panspermia theory seemed dead in the (lifeless) waters, later evidence has suggested that ancient life-forms may have been capable of surviving the harsh atmospheric conditions of space. In 2011, it was found that certain types of microbes (brilliantly named extremophiles for their hardy resistance to the most extreme conditions- including nuclear reactors) could survive in frozen environments such as underground lakes in Antarctica. The adaptations necessary to live in such a severe environment would be essential if they were to be successfully carried through space on ice-cold comets. Furthermore, experimental data has proven that organic molecules could survive prolonged atmospheric re-entry.

This week’s latest research suggests organic material can survive the capture, transport and impact of a high force contact event. The Darwin crater in Western Tanzania (a crater left from an impact with the earth 800,000 years ago) created impact glass due to the high temperature and pressure associated with the collision. Analysis of the glass has found surprising evidence for the organic remnants of the ancient ecosystem which was hit by the meteor. This is the first study of its kind to present evidence of life surviving either on the terrestrial surface or inside a meteorite that has impacted Earth. While this research does bring some weight to the Panspermia hypothesis, the Darwin crater is relatively small and it has yet to be proven that life could survive a much bigger impact.

Though still only a theory, the Panspermia hypothesis does have some weighty scientific evidence to pin down the more sci-fi elements. Life on earth may not have extraterrestrial origins, but the potential for microbes to survive in the most inhospitable environments may provide interesting developments in the future.

Science Quarks and Quirks

Saturday, 16 November 2013

Our Parents are Aliens?

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