November 11, 2011
Whiskers Were An Important Evolutionary Milestone For Mammals
Researchers have found that moveable whiskers on rats and mice were an important milestone in the evolution of mammals from reptiles.
The team used high-speed digital video recording and automatic tracking to discover how rodents move their whiskers back-and-forth at high speed.
This behavior, known as whisking, allows mice or rats to accurately determine the position, shape and texture of objects, make decisions about objects, and use the information to build environmental maps.
The team found that rodents move their whiskers back-and-forth when running in a straight line, but when turning they bias their whisker movements in the direction of a turn.
The researchers have shown that whisking is also seen in the grey short-tailed opossum. This animal has similarities to an early mammal that would have lived over 125 million years ago.
The research suggests that some of the first mammals may have whisked like modern rodents, and that the appearance of moveable whiskers was pivotal in the evolution of mammals from reptiles.
"This latest research suggests that alongside becoming warm-blooded, giving birth to live young, and having an enlarged brain, the emergence of a new tactile sense based on moveable facial whiskers was an important step along the evolutionary path to modern mammals," Professor Tony Prescott of the University of Sheffield said in a press release. "Although humans no longer have moveable whiskers they were a critical feature of our early mammalian ancestors."
The scientists found that the earliest mammals were nocturnal and tree-dwelling, and in order to move successfully in their environment they needed to integrate information from multiple senses.
They said that facial whiskers provided mammals with a new tactile sense that is not available to reptiles and could help them get around in the dark.
The team is using their discovery to develop animal-like robots that can use artificial whiskers to navigate without vision.
The robots could have applications in search-and-rescue sites where vision is compromised by smoke or dust.
The research was published in Philosophical Transactions of the Royal Society B.
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