Microbes Closest to Complex Life Were Filmed Crawling

Researchers have filmed living Asgard archaea, single-celled microbes without a nucleus that are considered the closest known relatives of complex cells, crawling across a glass surface. The work was published in Nature on September 30, 2026.

Crawling is a defining behavior of complex cells, the kind with a nucleus that makes up animals, plants and fungi. The authors describe the shape changes and movement they recorded as unique among microbes that lack one.

Philipp Radler, Christa Schleper and colleagues at the University of Vienna used live-cell microscopy on two cultivated Asgard lineages, Lokiarchaea and Hodarchaea. Both changed shape markedly within minutes, growing and pulling back long, thin arms at 1.5 to 4.8 micrometers per minute. Once a cell had stuck to the glass, it used those arms to haul itself along. Adding selected inhibitors of actin, the protein that builds the internal scaffolding of complex cells, stopped the movement. The authors say that points to a central role for actin.

The handful of Asgard archaea that can be grown in culture have an unusual shape, a central cell body with several arms extending from it, each filled with scaffolding built from actin.

The authors propose the trait may have mattered for the origin of the first complex cells, which are thought to have formed when an Asgard archaeon and a bacterium came together, the bacterium becoming the mitochondria.