The Shocking Discovery of Gears in Nature

Splined shafts

Man made custom gears are one of the oldest tools used to propel motion and power machinery. There are many different types of gears, and the choice of which one to use depends on the job that needs to be done. Bevel gears are internal gears with steel shafts mounted at a 90 degree angle, and the overall gear is shaped like a right circular cone. Just some applications of bevel gears are cars, boats, power plants, hand drills and printing presses. Helical gears either have parallel steel shafts or crossed steel shafts, with the former being the most common. They have similar applications to bevel gears, but can carry more weight.

Gear manufacturing companies were critical in the emergence of the Industrial Revolution in the 18th century. This marked the transition from hand production to manufacture by machines, and much of the advanced industrial machinery required gears to transmit motion. For centuries scholars have believed that humans were the first ones to invent these incredibly useful tools, but recently scientists have discovered a gear in nature — a small insect that uses gears to leap from plant to plant.

The first discovery of interlocking gears in nature

The insect is known as Issus coleoptratus and lives out its days in gardens throughout Europe, hopping from one plant to another to seek out food and friends. What’s amazing about this seemingly simple creature is the mechanism by which it jumps. Each of its hind legs is equipped with a gear and they are usually separated. When the insect prepares for a big jump, it brings the two gears together and the sets of teeth lock to coordinate the motion. The synchronous motion of the legs as a result of the gears working together results in a smooth and effective mechanism of movement. The insect won’t spiral out of control when in the air because its movement is symmetrical on each side.

Evolutionary gears allow a fast response

The most common way animals move is by sending information from the nervous system (brain) to the muscles, and from here the brain has to pay attention to carefully coordinate the movement from beginning to end. In the case of the Issus coleoptratus, the mechanical gear system allows the insect to send a signal from the brain to the muscle that controls the gears. As soon as one of the legs starts to propel forward motion, the gears lock together and the insect jumps. Once it begins, the motion is perfectly coordinated by the gear system throughout the entire jump, without intervention from the brain. Scientist Malcolm Burrows says that this mechanical system is even more precise than the highly specific nervous system. Without such sophisticated gears to guide its motion, this very tiny insect could spin out of control with even the slightest discrepancy in movement in leg motion. Exact coordination of movement can only be achieved with gears.

The natural gears are almost identical to man made gears

Perhaps most shocking about this discovery is how similar these naturally occurring gears are to the ones engineered by humans. The gears of this insect are quite similar to bicycle gears and car gear boxes. In all of these gear types, the gear teeth are rounded and connect to a gear strip. This serves to prevent teeth from breaking when they are hit with a lot of force, in other words it’s a very effective shock absorbing mechanism.

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