Tiny Robotic Insects Shine a Light on an Evolutionary Mystery, Through "Robophysics" Experimentation

Researchers from the University of California San Diego and the Georgia Institute of Technology believe they have shone new light onto how insects evolved two distinct flight strategies — by building tiny winged robots for "robophysics" experiments.

"We were able to provide an understanding of how the transition between asynchronous and synchronous flight could occur," explains Nick Gravish, professor of mechanical engineering and a senior author on the paper detailing the team's work. "By building a flapping wing robot, we helped provide an answer to an evolutionary question in biology."

That question: why some insects use synchronous flight where wing muscles are activated by conscious brain activity and why others use asynchronous flight in which wing muscles are activated without the nervous system being directly involved — and, a thornier question, why some insects, like the hawkmoth, evolved from synchronous to asynchronous flight and back again.

By building tiny insect-size robots, the researchers were able to conduct experiments which would have been impossible on actual insects — such as emulating different combinations of synchronous and asynchronous fight muscles to investigate which transitions may have occurred during the moth's evolution. This approach, dubbed "robophysics," delivered an answer — and a surprising finding.

"One of the biggest evolutionary findings here is that these transitions are occurring in both directions, and that instead of multiple independent origins of asynchronous muscle there's actually only one," explains Brett Aiello, assistant professor of biology and co-lead author. "From that one independent origin, multiple revisions back to synchrony have occurred."

"Our findings are pretty robust to all different experimental conditions," claims co-lead author Jeff Gau. "We’re looking back 400 million years into how ancient insect muscles must have behaved from an evolutionary standpoint."

The team's research may also have an impact outside evolutionary biology: the researchers believe that their work could lead to robots using asynchronous motors to better respond to rapid changes in environmental conditions, such as a gust of wind, and in building better flapping-wing robots. "This type of work could help usher in a new era of responsive and adaptive flapping wing systems," Gravish claims.

The team's paper is scheduled for publication in the journal Nature, but is not yet publicly available.

Main article image courtesy of Erik Jepsen/UC San Diego.