American Institute of Physics reports that "scrawnier people are more likely to perceive an approaching sound as closer than it actually is. This connection between physical fitness and the brain's auditory system may have evolved to help the weak get out of the way of approaching danger."

That's the latest finding of evolutionary psychologist John Neuhoff and colleagues at The College of Wooster in Ohio, who study "looming" sounds. Participants in their study listened to a tone moving toward them and pressed a button when they thought the sound had arrived directly in front of them. Nearly everyone pushed the button too early, which Neuhoff interprets as an adaptation that helps human beings to anticipate and avoid danger.

The team also tested the fitness levels of the listeners and found that those better equipped to handle danger allowed the sound get closer. Individuals with greater upper body strength and/or stronger cardiovascular systems waited longer to push the button, while subjects in poorer physical shape gave themselves a greater "margin of safety."

The research expands upon previous work showing that women respond to looming sounds sooner than their typically larger, stronger male counterparts -- though both groups perceive receding sounds equally. Rhesus monkeys also spend less time looking at receding sounds than approaching sounds. "These reactions are influenced by evolutionary forces; it's a good thing to respond a little bit early and, evolutionarily, it doesn't cost much," says Neuhoff.

Read the Abstract at: http://asa.aip.org/web2/asa/abstracts/search.may09/asa840.html