Big voices

One of the funniest scenes in the Monty Python movie Life of Brian is when a man is condemned to be stoned for saying "Jehovah," and the High Priest (played by John Cleese) is facing a crowd which is already armed with stones, ready to carry out the sentence.  The crowd, unbeknownst to the High Priest, is made up of women (who by law are forbidden from being there), and it's even funnier because that means the crowd was men playing women who were pretending they were men.

Well, at one point in the proceedings, the High Priest says the word "Jehovah" and gets clunked in the head by a rock.  He then demands to know who threw the rock.

A chorus of high-pitched, pseudo-feminine voices shouts, "She did!  She did!  She did!... um...."  (continuing in deeper, masculine voices)  "He did!  He did!  He did!"

This was the first thing my rather loopy brain thought of when I read a paper yesterday in Biology Letters.  In "Acoustic Allometry and Vocal Learning in Mammals," by Maxime Garcia (of the University of Zurich) and Andrea Ravignani (of the Max Planck Institute for Psycholinguistics), we find out that "dishonest signaling" -- using a voice that makes you sound bigger or more threatening than you actually are -- has been found in dozens of mammalian species.

The authors write:

Vocal production learning (VPL) can be defined as the experience-driven ability, rare among mammals, to modify existing vocalizations, to produce novel sounds or to imitate sounds that do not belong to an individual's vocal repertoire...  VPL inherently involves modulation of acoustic features related to the source, filter or both.  Yet, different species have varying degrees of control over the anatomical components involved in phonation.  For instance, despite a generally assumed lack of vocal control some non-human primates might have limited sound production plasticity, including for non-voiced sounds.  While the presence of VPL in non-human primates is debated, strong evidence for VPL has been found to date in humans and four other mammalian clades: non-otariid Pinnipedia, Elephantidae, Chiroptera and Cetacea.

"If you saw a Chihuahua barking as deep as a Rottweiler, you would definitely be surprised," said study co-author Andrea Ravignani, in an interview with Science Daily.  "Nature is full of animals like squeaky-Rottweilers and tenor-Chihuahuas...  Some animals fake their size by developing larger vocal organs that lower their sound, which makes them sound larger than you would expect.  Other animals are good at controlling the sounds they produce.  Such strategies -- 'dishonest signaling' -- could be driven by sexual selection, as males with larger body size or superior singing skills (hitting very high or low notes) attract more females (or vice versa)."

I know one good example of little animal/big voice from my own back yard -- the Carolina Wren (Thryothorus ludovicianus).  It's a tiny thing, what birders call an "LBJ" (Little Brown Job), but its outsized shriek of "TEAKETTLE TEAKETTLE TEAKETTLE" frequently wakes me up at four in the morning during the spring and early summer, especially given that there's one of 'em who likes to sing from the branches of the box elder tree right outside my bedroom window.  But this is volume, not pitch.  For misleading pitch, there's none that can compete -- at least in the bird world -- with the Great Potoo (Nyctibius grandis) of the rainforests of South America.  Take a listen to this:

Since this bird is nocturnal, and (as you can see) is very cryptically colored, a lot of the natives didn't realize that sound was a bird for a long time.  Their explanation -- that there was a horrible monster out there in the forest roaming around at night -- is completely understandable, given what its vocalizations sound like.

So the capacity to create misleading sounds isn't the sole provenance of the Monty Python crew's fake falsettos.  There are lots of animal species that do the same thing, either to frighten off potential predators or to sound sexier for potential mates.

Or, perhaps, to give a misleading answer to questions like, "Are there any women here today?... good, very well then."

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This week's Skeptophilia book recommendation of the week is for anyone who likes quick, incisive takes on scientific topics: When Einstein Walked with Gödel: Excursions to the Edge of Thought by the talented science writer Jim Holt.

When Einstein Walked with Gödel is a series of essays that explores some of the deepest and most perplexing topics humanity has ever investigated -- the nature of time, the implications of relativity, string theory, and quantum mechanics, the perception of beauty in mathematics, and the ultimate fate of the universe.  Holt's lucid style brings these difficult ideas to the layperson without blunting their scientific rigor, and you'll come away with a perspective on the bizarre and mind-boggling farthest reaches of science.  Along the way you'll meet some of the key players in this ongoing effort -- the brilliant, eccentric, and fascinating scientists themselves.

It's a wonderful read, and anyone who is an aficionado of the sciences shouldn't miss it.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]