"DISCOVERY OF EARTH'S EARLIEST FOSSILS -- SOLUTION TO DARWIN'S DILEMMA"
In 1859, in his grand work On the Origin of Species, Charles Darwin broached what he regarded to be the most vexing problem facing his theory of evolution -- the complete lack of a fossil record of life prior to the rise of shelly invertebrate animals that marks the beginning of the Cambrian Period of geologic time (~550 million years ago), an absence he described as "inexplicable" that could be "truly urged as a valid argument" against his all-embracing synthesis. For more than 100 years, the missing Precambrian history of life stood out as one of the greatest unsolved mysteries in natural science. Over recent decades, however -- after a century of trial and error, search and eventual discovery -- life's ancient roots have finally been uncovered as the documented record of life has been extended to some 3,500 million years ago, an age more than three-quarters that of the planet itself. An immense early fossil record, unknown and assumed unknowable, has been unearthed to reveal a microbe-dominated evolutionary progression that stretches seven times farther into the geologic past than had previously been thought. Life began far earlier, and evidently evolved initially much farther and faster than anyone had imagined.