General Physics Physics Seminar 25 September 2003


Origin of Life on Earth

Nanne Nanninga

Swammerdam Institute for Life Sciences
University of Amsterdam, Kruislaan 316, 1098 SM Amsterdam, The Netherlands


Because fossils of the earliest organism are lacking, that is of organisms present during the first billion years of the earth's existence, there is no direct evidence about their evolution. The earliest traces of organisms pertain to already quite sophisticated photosynthetic blue algae (cyanobacteria).They were claimed to be present in rocks dating about 3.5 billion years ago. Assuming that the earth arose 4.5 billion years ago this would implicate that early evolution was very fast. Recently, the nature and age of these fossils have been challenged. If correct, the earliest fossils would date about 2 billion years ago. As will be explained this would make sense.

By necessity laboratory experiments aim at screening primitive abiotic conditions to find out whether and to what extent they can provide for organic building blocks. Since the early experiments of Miller cs. (1953) a wealth of information has been gathered. The most exciting twist has been the notion that nucleic acids came before proteins ("the RNA-world)". This idea took shape when it was found that RNA can function as an enzyme. The discovery that bacteria exist that can grow under "impossible" conditions has led to research aimed at making biological building blocks under extreme conditions. In line with this approach researchers are also investigating to what extent extraterrestrial components have contributed to the origin of life.

A recent approach makes use of genomic sequence data to construct primitive organisms from existing bacteria in the laboratory. This represents reversed evolution, which might reveal how a primitive organism might have looked like.