Life 'began in rocks under the ocean'

Life on Earth began in tiny metal spheres in rocks thousands of feet under the ocean, a new theory claims.

One of evolution's great mysteries can be explained by the formation of microscopic "incubators" which allowed complex biological molecules to form, said scientists.

The non-living "cells" formed in iron sulphide rocks near hot, hydrothermal vents on the sea floor, according to the theory formulated by Professor William Martin of the University of Dusseldorf and Professor Michael Russell of the Scottish Environmental Research Centre in Glasgow.

Their theory turns conventional theories upside down by suggesting cells, rather than replicating molecules, came first. These metallic cells were non-living.

The theory, published in the Philosophical Transactions of the Royal Society proposes that these first capsules of iron sulphide were formed in total darkness on the ocean floor, where they allowed the complex chemistry necessary for life to begin.

"As hydrothermal fluid emerged from the Earth's crust, it reacted inside tiny metal sulphide cavities," Professor Russell said. "They provided the right micro-environment for chemical reactions to take place. Iron sulphide cells, we argue, are where life began."