Why Do We Make the Sounds that We Do? - The Origins of Anthrophony

I recently read two science articles that got me thinking about humanity and why we're the noisy creatures that we are. The first examined the origins of laughter: one theory is that it's a release mechanism for both the individual and the group, a sort of acoustic 'all clear' to let everyone know that the tension has been resolved. (How much humor is based on incongruity and thus surprise, and who hasn't laughed after a collective gasp during a scary movie?) The second reported that the various species sharing a rain forest each stick to their own acoustic frequency range as closely as if regulated by the FCC. The author called this stratified sharing system biophony, and the human spectrum-straddling 'anthrophony'. It made me think about all of the various sounds we make, and wonder what purpose each one may have served, and what purposes they continue to serve.

Snoring, for instance, has distinct disadvantages in a primal environment. It may attract nocturnal predators, frighten away potential prey, alert human enemies both to one's presence and one's somnolent defenselessness, and frequently accompanies health problems that may interfere at the very least with one's ability to get a good night's sleep. With all of these selection pressures against it, should we dismiss snoring as a regrettable oversight of natural selection, or look for positive selection pressures? Just as laughter broadcasts the non-verbal message 'all is well; you can relax', snoring announces 'I've relaxed enough to go to sleep; its probably safe for you to do the same.' The more snores you hear, the more comfortable you can be in your decision to go to sleep yourself: and sleep is a task for which comfort is a necessary prerequisite.

What about sneezing? Many mammals do it, for the same reason we do: to expel dust and germs from the breathing passage. But the process is distinctly louder in humans, with many of us learning to vocalize as we sneeze so that a sneeze resembles actually shouting the word 'ACHOO!' Is there any purpose to this added volume? It's possible that people vocalize their sneezes for the same reason they start meaningless conversations in elevators: they're almost pathologically social creatures. This in itself has selection value in a socially-oriented species. At the same time, there may be more direct pressures at work. What does a sneeze announce? It announces the presence of contaminants or irritants in the air. Like the other signs, it has an 'all clear' aspect to it: the more loudly vocalized it is, the less probable that threat is nearby. It may warn others that the sneezer is carrying an infection: numerous superstitions associating sneezes with bad luck suggest such a context. Coughing and throat clearing would seem to have similar meanings, although complicated, like laughter, by the fact that they are semi-voluntary actions.

Finally, consider the place of the scream in non-verbal communication. Most screams are intentional communication; even a non-verbal scream may be deliberately chosen to convey a specific message, e.g., "I'm very angry at you and shall attempt to hurt you", "I'm in a distressing situation and would like someone to come to my aid," or "It is imperative that I obtain your attention for a moment." At other times, however, there is no message behind the scream; it is delivered at the hest of a catharsis so inexorable that it might as well be a sneeze. Such screams frequently occur at moments of extreme emotion where rational thought is interrupted by anger, grief, fear, or even amusement. The man who screams at an assailant may or may not be choosing a scream to communicate an idea; the man who screams at a tennis ball or even a computer screen is almost certainly not. (One could argue that the screamer is anthropomorphosizing his target, but it seems more probably to posit an involuntarily noise than involuntary abstract thinking.)

When we listen to birds singing, dogs barking, cats mewing, we typically look for explanations of their behavior based on stimuli, not volition. It is instructive to do the same when we hear humans making some of the many noises that comprise the world's anthrophony.