LUCA, not Adam or Eve, our original ancestor

December 18th, 2008 - 11:17 am ICT by IANS  

Toronto, Dec 18 (IANS) A new theory proposed by an evolutionary geneticist suggests that our last universal common ancestor or LUCA, a 3.8 billion-year-old organism, was not the creature usually imagined. “It is generally believed that LUCA was a bit like one of those weird organisms living in the hot vents along the continental ridges deep in the oceans today (above 90 degrees Celsius),” said Nicolas Lartillot, the study’s co-author and a bio-informatics professor at the Montreal University.

“However, our data suggests that LUCA was actually sensitive to warmer temperatures and lived in a climate below 50 degrees.”

The research team compared genetic information from modern organisms to characterise the ancient ancestor of all life on earth, said a Montreal University statement. The study was reported in a recent issue of Nature.

“Our research is much like studying the etymology of modern languages so as to reveal fundamental things about their evolution,” said Lartillot.

“We identified common genetic traits between animals, plant, bacteria, and used them to create a tree of life with branches representing separate species. These all stemmed from the same trunk, LUCA, the genetic makeup that we then further characterised.”

The group’s findings are an important step towards reconciling conflicting ideas about LUCA. In particular, they are much more compatible with the theory of an early RNA world, where early life on Earth was composed of ribonucleic acid (RNA), rather than deoxyribonucleic acid (DNA).

However, RNA is particularly sensitive to heat and is unlikely to be stable in the hot temperatures of the early Earth.

Lartillot’s data indicates that LUCA found a cooler micro-climate to develop, which helps resolve this paradox and shows that environmental micro domains played a critical role in the development of life on Earth.

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