Tuesday, 25 October 2011

New Evidence For Greenland As The Precise Birthplace For The First Life Forms

Ancient serpentine mud flows at the Isua Greenstone Belts, Greenland
For many years, scientists have studied how life originated. Many different theories based upon complex organic chemistry and intriguing geographical concepts, have been put forward. Yet the one thing that these studies do not tell us is exactly where on Earth life originated. There are a number of possible sites, but up until now no strong evidence for any of them. Yet compelling new research suggests that south west Greenland may be the place where the planet's greatest miracle began.

One of the older rock formations on Earth are the Isua Greenstone Belts. Greenstone is a type of metamorphic rock found in active tectonic regions. Some of the largest formations formed early on in our planet's history due to the particularly violent and volcanic nature of the Hadean, Archaean and Proterozoic eons. While it seems far fetched that such a delicate thing like life could have originated in a harsh, volcanic environment, volcanoes (in this case mud volcanoes) are actually a very likely place for abiogenesis (the process where inert chemicals form organic beings) to take place.

These highly unstable points on the crust are constantly spewing out chemicals and compounds which are needed to form complex, organic molecules. The geological conditions are also favourable. In an earlier post, I reported on how the cavities inside pumice rocks could have acted like tiny pieces of laboratory apparatus, which would have accelerated the process of abiogenesis. New research shows that the Isua Greenstone Belts combine together the most favourable conditions for the creation of life.

An international team led by researchers from the Laboratoire de Geologie de Lyon analysed the 3.8 billion year old serpentine rocks (a type of greenstone) to look for chemical indicators which would provide clues as to the conditions of the Isua Greenstone Belts at the time when they were forming. 3.8 billion year ago, the area was a vast volcanic complex. All the conditions present favoured abiogenesis. First and foremost, mud volcanoes produce vast amounts hydrogen, methane, ammonia, water and many other metals and compounds needed for the synthesis of amino acids.

This specific study centres its research around this main piece of evidence. The scientists also looked at the levels of zinc to study the pH of the mud. They found that the water was alkaline, perfect for the stabilisation of amino acids. Amino acids are very fragile, and as they are the building blocks of proteins which in turn make up DNA, if they are damaged, life forms cannot be created.

A stable chemical environment protected from the sun's rays such as the one presented by the Isua Greenstone Belts is perfect for abiogenesis to occur. Previously, a popular place for the origins of life were deep sea hydrothermal vents. The real problem with this theory is that the water around such vents is highly acidic and therefore does not favour the synthesis of amino acids. A second point against the vents is that the chemical reactions in abiogenesis require a high energy source.

The 100 to 400 degrees Celsius temperatures of the vents is just not enough. An experiment in 1956 by Stanley Miller and Harold Urey used a 10,00 volt spark to create amino acids. Volcanoes on the other hand produce large lightning storms with far higher voltage than the Miller/Urey experiment, due to static electricity generated by the ash particles in the air. When all these conditions are put together, it becomes clear as to why the study suggests that the Isua Greenstone Belts are the birthplace of life.