3 Physicists Derive Universal Poop-Coiling Law From 1880 Darwin Observations

Q: What universal physics law connects Darwin's worms to a potential new emoji?

The link is **elastic rope-coiling theory**, the universal mechanics that describe how a soft, extruded filament bends into spirals under gravity and its own stiffness. In the new *Nature Communications* study, physicists showed that both the familiar downward, soft-serve-like poop coil and the upward “antigravitational” coils made by lugworms follow the same law. What changes the final shape is not a different principle, but the balance between gravity, extrusion direction, and material properties such as stiffness, diameter, and density. For lugworms, which push feces upward from their burrows, the coils keep a nearly constant width instead of tapering. The researchers found this matches the gravitational regime of elastic rope-coiling theory and can be quantified by the scaling relation \(R \sim (d^{2}E/\rho g)^{1/3}\), where coil radius depends on diameter, stiffness, density, and gravity. That is the physics connection from Darwin’s worm castings to a possible new emoji: the same universal coiling law explains both the classic poop emoji shape and the newly proposed “antigravitational poo.”

1 articles · Updated · ScienceAlert · Jun 27

A Nature Communications study found animal feces across species follow elastic rope-coiling physics, extending Charles Darwin’s 1880 descriptions of spiral worm castings.
Lugworms helped reveal the rule because they defecate upward from U-shaped burrows, producing constant-width coils instead of the tapered cone seen in the poop emoji.
Tests comparing fresh lugworm castings with pea dough, rice noodles and spaghetti showed the unusual shape comes from upward extrusion and material stiffness, not a different underlying law.
The researchers said the geometry likely helps lugworm burrows resist clogging and tidal forces, and argued the findings broaden understanding of how organisms use physics in functional morphology.
The team also plans to propose a second, anti-gravitational poop emoji to Unicode, reflecting a coil form missing from current digital shorthand.