Plate Nº 23 · recorded September 30, 2026
Biology & EvolutionReported finding
Crawling Motion May Be Far Older Than Complex Life Itself
Researchers filmed Asgard archaea crawling across surfaces with actin-driven projections, hinting that complex cell movement predates the first eukaryotes by a wide margin.
By Priya Raman3 min read650 words
In brief
- University of Vienna-led team filmed Asgard archaea crawling using dynamic protrusions, a behavior previously known only in eukaryotes.
- Actin inhibitors suppressed the movement, suggesting an actin-based cytoskeleton — the same machinery that drives motility in human cells.
- The study, published in Nature (2026), used oxygen-free live-cell microscopy, enabling the first empirical tests of models for the origin of complex life.
Our closest known microbial relatives can crawl. That, in essence, is the headline from a new study published in the journal Nature, and it may force scientists to rethink when and how the ability to move like a complex cell first evolved.
A team of microbiologists led by the University of Vienna has captured live footage of Asgard archaea — single-celled organisms whose volume is roughly a thousand times smaller than that of a human cell — actively changing shape and creeping across surfaces using long, thin cell projections. Until now, researchers had observed this kind of crawling behavior only in eukaryotes: the group that includes all animals, plants, fungi and protists, among them human immune cells that patrol the body in exactly this fashion.
Why Asgard archaea matter
Asgard archaea occupy a special place in the story of life. Current models propose that the first eukaryotes emerged around 2 billion years ago from the fusion of a bacterium with an ancestor of today's Asgard archaea. That ancient merger, the thinking goes, eventually gave rise to mitochondria — the power plants of complex cells — and to every complex organism on Earth, ourselves included. Asgard archaea are therefore a crucial building block in current accounts of how complex life arose.
Yet their biology has remained poorly understood. It was only recently, in 2020 and 2023, that researchers managed to cultivate the first two specimens of these organisms: one at the JAMSTEC Institute in Japan, the other in the laboratory of Christa Schleper at the University of Vienna. Most of what scientists knew before came from DNA sequencing and electron microscopy. Those static images showed striking shapes — a round cell body ringed by delicate projections that can reach up to 20 times the length of the body itself — but they said nothing about how the cells actually behave.
Filming cells that hate oxygen
Philipp Radler, working in Schleper's lab, closed that gap. The researchers placed Asgard archaea in an oxygen-free environment and filmed the living cells under a microscope. They worked with two strains: a Lokiarchaeon cultivated in Vienna and a Heimdallarchaeon cultivated in Japan.
The footage revealed something nobody had seen in a microbe. Both organisms drastically reshape themselves every minute. They extend long protrusions, retract them, and use these dynamic appendages to attach to surfaces and explore them with a crawling motion previously undocumented outside eukaryotes.
The international team — which included Japanese microbiologists along with collaborators from IST Austria and HZI Braunschweig in Germany — then ran a key experiment. When they applied actin inhibitors to the cells, the dynamic behavior stopped. Actin is a protein that builds the cytoskeleton, the internal scaffold that controls shape and movement in human cells. The result suggests that an actin-based cytoskeleton plays a central role in Asgard archaea motility too.
An evolutionary twist
The implications reach back billions of years. If Asgard archaea crawl using actin-driven machinery, then the toolkit for complex cell movement may have existed long before the first eukaryotes appeared. These cellular innovations could even have played a role in the ancient symbiosis between a bacterium and an Asgard ancestor — the partnership from which mitochondria later emerged.
The findings come with clear limits. The study covers two cultivated strains out of a diverse group, and live-cell observation under artificial oxygen-free laboratory conditions may not fully reflect how these organisms behave in their natural habitats, typically deep marine sediments. The evolutionary interpretations remain models, not settled facts.
Still, the method itself marks a milestone. The oxygen-free live-cell microscopy developed for this study now makes it possible, for the first time, to test models of the origin of complex life empirically — by watching, rather than merely inferring from DNA.
The paper, led by Christa Schleper and titled "Dynamic protrusions mediate crawling motility in Asgard Archaea," appears in Nature (2026), DOI: 10.1038/s41586-026-11063-9.
via Phys.org Biology (Source)
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Senior reporter covering industry trends and analytics at SciBeat.
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