A newly discovered life form could help resolve one of the most contentious conundrums in modern biology. All organisms on Earth are classified as either prokaryotes, which have simple cells, or eukaryotes, which have larger, more complex cells. But the two cell types are so divergent that understanding how one evolved from the other has foxed biologists. The new microbes, reported in Nature journal, go some way to bridging that gap. They have been named Lokiarchaeota, partly after the Loki's Castle volcanic vent system lying 15km away from the site where the microbes' genetic material was isolated in cold marine...