Speaking of mechanical gears, I believe everyone will not be unfamiliar, although we have seen a variety of types of mechanical gears, but they all have one thing in common, that is, they are all made by humans, so usually we will think that mechanical gears should be unique to human inventions, so is this really the case?
Actually, no, because in nature, there is an insect that has already evolved a "mechanical gear", and they are the "Issus coleoptratus".
"Issus planthoppers" belong to the order Coleoptera, their body size is relatively small, the average body length is only about 3 mm, they are mainly found in the European region, usually live in humid environments, feed on the sap of plants, they like to jump between leaves or blades of grass, can easily jump more than 100 times their body length, and can also land exactly where they want to go.
An insect with such a great jumping ability is certainly worth looking into. Interestingly, during closer observation using a high-resolution microscope, the scientists were surprised to find that the insect had "mechanical gears" on its hind legs — a pair of tiny structures on the tibiae of their hind legs that resemble human-made mechanical gears with precise teeth and clearances.
Amazingly, their structure not only looks very similar to a human-made mechanical gear, but also has the corresponding function.
Issus planthoppers have a "mechanical gear" on each hind leg that has the same "number of teeth" (usually 10 to 12), and each "tooth" has a rounded corner curve at the bottom, a "design" that is often seen in human-made mechanical gears, as it effectively reduces the risk of wear and shear.
Before jumping, the "Issus planthoppers" will first bend their hind legs backwards to form a jumping position, at this time the "mechanical gears" on their hind legs will be neatly bitten together, and in the subsequent force process, the "mechanical gears" will rotate at a very fast speed in a short time, so that the "Issus planthoppers" can obtain a high acceleration, and its instantaneous speed can be as high as about 3.9 meters per second.
It is important to know that in this process, the "mechanical gear" of the "Issus planthopper" has a more subtle role in addition to the function of transmitting power.
In order to improve the accuracy of the jump, the "Issus planthopper" needs to try to make both of its hind legs exert force at the same time, if one of the hind legs is a little slower, they will not be able to accurately control the direction and distance of their jump, and the "mechanical gears" that are tightly snapped together can ensure that the hind legs exert force at almost the same time.
In fact, the take-off time of the "Issus planthopper" is only about 30 microseconds, and if their hind legs do not have "mechanical gears", then it is difficult to precisely control their two hind legs almost simultaneously in such a short period of time with the coordination of their nervous system.
I have to say that the "Issus planthopper" really opened our eyes, and at the same time, it is easy to make people wonder: is this really evolutionary? To this, scientists have given a positive answer.
Scientists point out that the "mechanical gears" of the hind legs of the Issus planthopper actually only appear in their nymph stage, during which they are relatively vulnerable, and from an evolutionary point of view, individuals with "mechanical gears" are more accurate in their jumps and are more likely to survive.
Of course, the "mechanical gears" of this insect do not appear out of thin air, but actually go through a long and gradual process. Scientists speculate that in the process of reproduction from generation to generation, their exoskeletons will also continue to undergo some changes due to "genetic mutations", and in the beginning, some individuals may have some small mutations, so that some of the exoskeletons of their hind legs can bite each other, thus improving the accuracy of their jumps.
The improvement of jumping accuracy means an increase in the probability of survival, so in the following days, there are more and more individuals with this characteristic, and as time passes, the changes in the exoskeleton of their hind legs tend to be more and more easy to bite each other, and in the process, some individuals gradually evolve structures with the shape of gears.
For these individuals, their survival probability is undoubtedly stronger than other individuals, so they have become more and more common in the population, and over a long period of time, their "gears" have become more and more perfect gear shapes, and gradually evolved into the "mechanical gears" we see now, as for other individuals, they have long been "eliminated" by the harsh nature.
It is worth noting that although some organisms with gear-like structures have been found before the "Issus planthopper", the "gears" of these creatures are "imaginary" and do not function as mechanical gears, and as far as the current situation is concerned, the "Issus planthopper" is the only creature known on Earth with a functional gear system. I have to say, nature is really amazing, don't you think?