Unique structure of elephant whiskers give them built-in sensing “intelligence”

An elephant’s trunk is a wonderful thing, flexible enough to bend and stretch as it forages for food, but also rigid enough to grasp and maneuver even delicate objects like peanuts or tortilla chips. This is because the core is very sensitive when it comes to feeling touch. Scientists have determined that the whiskers that line the trunk are crucial for this sensitivity thanks to their unique structure, amounting to a kind of innate “material intelligence,” according to a new paper published in the journal Science.

As noted previously, there is a long history of the study of whiskers (vibrissae) in mammals. According to various previous studies, rats, cats, tree squirrels, manatees, harbor seals, sea otters, big cats, shrews, tammar wallabies, sea lions, and naked mole rats all share strikingly similar basic analyses. Among other potential applications, such research could one day allow scientists to construct artificial whiskers as tactile sensors in robotics, as well as learn more about human touch.

Whiskers are much more complex than one might think, both in structure and function. Rats, for example, have about 30 large whiskers and dozens of smaller ones, which are part of a complex “sensorimotor scanning system” that allows the rat to perform tasks as diverse as texture analysis, active touch for path finding, pattern recognition, and object localization, simply by scanning the terrain with its whiskers.

Technically, whiskers are just hairs, a collection of dead keratin cells. It’s what they’re attached to that makes them as sensitive as human fingertips. Each rat whisker is inserted into a follicle that connects it to a “barrel” made up of 4,000 densely packed neurons. Together, they form a grid or network that serves as a topographical “map,” telling the rat’s brain exactly what objects are present and what movements are taking place in their immediate environment. All of these barrels are in turn linked together in a kind of neural network, so that the rat receives multidimensional cues about its environment. Rats’ whiskers also resonate at certain frequencies; there are shorter whiskers near the nose, and longer whiskers further back, allowing rats to create a sort of “frequency map” by pushing their noses everywhere