About 580 million years ago, life on Earth began a rapid period of change called the Cambrian Explosion, a period defined by the birth of new life forms over many millions of years that ultimately helped bring about the modern diversity of animals. Fossils help palaeontologists chronicle the evolution of life since then, but drawing a picture of life during the 3 billion years that preceded the Cambrian Period is challenging, because the soft-bodied Precambrian cells rarely left fossil imprints. However, those early life forms did leave behind one abundant microscopic fossil: DNA.
Pity poor Leif Ericsson. The Viking explorer may well have been the first European to reach the Americas, but it is a certain Genoan sailor who gets all the glory. Thanks to evidence that has until now consisted only of bare archeological remains and a bunch of Icelandic legends, Ericsson has long been treated as a footnote in American history: no holiday, no state capitals named after him, no little ditty to remind you of the date of his voyage. But a group of Icelandic and Spanish scientists studying one mysterious genetic sequence - and one woman who's been dead 1,000 years - may soon change that.