The hunt for Precambrian fossils: An abbreviated genealogy of the science

In 1859, in his great work On the Origin of Species, Darwin repeatedly raised what he regarded to be the most serious problem facing his theory of evolution – the lack of fossils predating the rise of shelly invertebrates that marks the beginning of the Cambrian Period of geological time (550 Ma), an “inexplicable” absence that could be “truly urged as a valid argument” against his all-embracing synthesis. This missing early fossil record posed a major dilemma, for Darwin's theory demanded firm linkage from the less advanced to the more evolved, from primitive microbes to protozoans to the rich faunas of the basal Phanerozoic for which no fossil evidence was known. For more than 100 years, the history of Precambrian life stood out as one of the greatest unsolved problems in natural science. In recent decades, however, understanding of life's early evolution has changed markedly as the documented fossil record has been extended seven-fold to some 3500 Ma, an age more than three-quarters that of the planet. This long-sought solution to Darwin's dilemma was set in motion by a small vanguard of workers who blazed the trail in the 1950s and 1960s, just as their course was charted by a few prescient pioneers of the previous century. All workers today, including the 28 participants in the recently held World Summit on Ancient Microscopic Fossils, have roots that can be traced to the pathfinders of a half-century ago.