Life came to Earth on a meteorite, say scientists

An article by Andrew Griffin, appearing in the 17 March issue of The Independent, tells the story:

Life on earth has long been a mystery, since the building blocks appear to have landed on the planet with no real explanation of how they got there. But a scientist has proposed one - those mysterious building blocks arrived here by crashing down with a meteorite.

Life must have begun with a genetic molecule, like DNA or RNA, that would be able to store the instructions needed to make proteins, which do the work of keeping life happening. But the cells that are around now can't make DNA without proteins. Each relies on the other, and scientists have been unable to tell which arrived first.

Similarly, none of those molecules can work without fatty lipids, which allow cells to store things. But enzymes need lipids to be able to create them.

Scientists have now proposed that all of the necessary compounds were around at the beginning of Earth, and may have come down from an icy comet. That comet could have splashed down on Earth, bringing the molecules and allowing them to join together and create life in pools on the Earth's surface.

The Earth was steadily being hit by comets for the first several hundred million years it was around, according to Science Mag.

The new research, published in Nature Chemistry, shows that the building blocks could be created using very simple chemicals. Those simple chemicals probably came to the Earth on those comets, Sutherland has proposed.

The chemicals, including hydrogen cyanide, were probably dispersed across the surface by those comets. The different building blocks would have been created separately, and then be washed into a pool together, according to Dave Deamer, a researcher on the origin of life who wasn't part of the research.

Source: independent.co.uk