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February 21, 2024

Functional mechanical gears found in insect

By ALBERT HUANG | September 27, 2013

As creative as our large human brains make us, the adaptive forces of nature often outsmart us. After all, it was these forces that pushed us to develop such meaty neo-cortices in the first place and made us the smartest species on earth.

Despite our strengths, we often have a narcissism of our uniqueness among the animal kingdoms that is chipped every day by revelations of the innovative leaps of nature and the power of biodiversity. In this case, it is the secret hidden within a little bug found commonly in England, called the “planthopper” that’s got scientists’ minds turning.

Researchers from the University of Cambridge have found this other showcase of Nature’s brilliance within the hind legs of the hopping bug, Issus coeleoptratus, also known as the “planthopper.”

By using a high speed camera, flipping the little guys on their backs and tickling the bugs with paintbrushes to make them kick, the team of zoologist Malcolm Burrows and engineer Gregory Sutton observed something amazing happen within 30 millionth of a second. The insects turn out to have tiny gears on their hind legs that synchronize their jumping motions faster than the speed of their own nervous systems.

Motivated by pure instinct, these bugs will jump before their nervous system realizes it. With their very own sets of miniscule teeth guarded by a gear strip, these little asymmetric cogs fit together tooth and nail to synchronize the bug’s jumps. It even has miniature gear strips providing shock-protection for the little teeth, as they lock together the hind legs of the baby Issus like a gear box to hold its legs in sync.

For such a fast movement, coordination is key. If the speed of the legs are off by even a little after take-off, the offset will force the bugs into a jolting yaw rotation, turning them into whirling tops.

Just imagine the havoc of an F-14 jet out of the movie Top Gun flaming out of one of its engines and going into a spin — that’s the importance of leg synchronization. Burrows and Sutton have an interesting theory based on the observation that they only found these gears on the nymph or juvenile forms, of the planthopper. They propose that these gears are like training wheels. For the weaker young bugs, the wheels help create absolute synchronicity by interlocking the joint movements of their two legs and providing strength for its jumps.

It is often the us humans, master mimics, take what we discover from nature to inspire our own creations and devices, from creating Velcro from burdock seeds, smart clothing from pine cones and cat’s eye reflectors from our feline friends. However, the discovery of nature’s first “clockwork organism” overturns one creation we thought we owned exclusively as an icon to human ingenuity from Archimedes to the rise of the Machine Age.

A form of convergent evolution, thought for us and biology for them, this extraordinary finding illuminates the overlap in utility we both found for the simple gear, and how nature and humanity share a common ocean of ingenuity. Nature has given us our share of inspiration, and we have matched it.


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