Scientists consider deep history of eukaryotes
R.B. PEDERSEN/CENTRE FOR GEOBIOLOGY/UNIV. OF BERGEN
Microbes discovered in Arctic mud could be the closest relatives yet found to the single-celled ancestor that swallowed a bacterium and made life so complicated. Biologists have proposed that this swallowing event, perhaps 1.8 billion years ago, led to complex cells with membrane-wrapped organelles, the hallmark of all eukaryotes from amoebas to zebras.
Researchers discovered the new phylum of microbes, dubbed Lokiarchaeota, by screening DNA from sediment (SN: 5/30/15, p. 6). Though no one has identified an actual cell yet, the new phylum appears to mingle genes similar to those in modern eukaryotes and genes from archaea, the sister group to bacteria. Analyses suggest the cells have