Scientists have uncovered a potential driver behind the evolution of multicellular life: the fluid dynamics of cooperative feeding in single-celled organisms. Published in Nature Physics, the study led by researchers at Emory University suggests that physical forces, not just chemistry, may have played a key role in this pivotal evolutionary step. The findings stem from observations of stentors—trumpet-shaped, single-celled organisms-whose feeding behaviors hint at how early life forms might have benefited from grouping.

The study began when lead author Shashank Shekhar, an assistant professor of physics at Emory University, observed stentors filter-feeding in lab dishes. By analyzing the fluid flows generated by their cilia, Shekhar and his team discovered that stentors clumped in pairs or colonies created stronger currents, enabling them to draw in more food from greater distances.

“The project started with beautiful images of the fluid flows,” Shekhar said. “Only later did we realize the evolutionary significance of this behavior.”

The researchers found that weaker stentors benefited more from joining forces, while stronger ones occasionally broke away, suggesting a dynamic balance of cooperation and opportunism. Mathematical models developed by co-authors Eva Kanso and Hanliang Guo confirmed that colony formation enhanced feeding efficiency on average.

Stentors, visible to the naked eye at 1–2 millimeters long, are named after the Greek herald Stentor due to their horn-like shape. Their ability to regenerate and form temporary colonies makes them a unique model for studying early multicellular behavior.

“It’s amazing that a single-celled organism with no brain or neurons developed behaviors for opportunism and cooperation,” Shekhar noted. “Perhaps these kinds of behaviors were hard-wired into organisms much earlier in evolution than we previously realized.”

The study offers a fresh perspective on how physical forces, alongside chemical processes, may have driven the transition to multicellular life. By revealing the advantages of cooperative feeding in stentors, the research opens new avenues for understanding the origins of complexity in living systems. Future work could explore whether similar dynamics apply to other organisms, shedding further light on one of biology’s greatest mysteries.