Academic journal article Science and Children

Functioning "Mechanical Gears" Seen in Nature for the First Time

Academic journal article Science and Children

Functioning "Mechanical Gears" Seen in Nature for the First Time

Article excerpt

Previously believed to be only manmade, a natural example of a functioning gear mechanism has been discovered in a common insect--showing that evolution developed interlocking cogs long before we did.

The juvenile Issus--a plant-hopping insect found in gardens across Europe--has hind-leg joints with curved coglike strips of opposing "teeth" that intermesh, rotating like mechanical gears to synchronize the animal's legs when it launches into a jump.

The finding demonstrates that gear mechanisms previously thought to be solely man-made have an evolutionary precedent. Scientists say this is the "first observation of mechanical gearing in a biological structure."

Through a combination of anatomical analysis and high-speed video capture of normal Issus movements, scientists from the University of Cambridge have been able to reveal these functioning natural gears for the first time. The findings are reported in the latest issue of the journal Science.

Each Issus gear tooth has a rounded corner at the point it connects to the gear strip, a feature identical to man-made gears such as bike gears--essentially a shock-absorbing mechanism to stop teeth from shearing off. The gear teeth on the opposing hind legs lock together like those in a car gearbox, ensuring almost complete synchronicity in leg movement--the legs always move within 30 microseconds of each other, with one microsecond equal to a millionth of a second. …

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