The world’s greatest Yodelers were found not in alpine villages, but in the rainforest of Latin America, where monkeys perform vocal gymnastics, even the most accomplished human singers breathlessly, according to groundbreaking new research.
Scientists have discovered that some New World monkeys can be more than five times the frequency range, more than five times larger than what humans can achieve, with some of them “super young people” spanning three musical octaves in a phone call. This extraordinary ability stems from the special anatomy that humans have lost during evolution to achieve a more stable speech.
“These results show how monkeys can exploit evolutionary features in their throat (vocal membrane), a function that can generate more calls, including these oversized calls,” explains Dr. Jacob Dunn, associate professor of evolutionary biology at Anglia Ruskin University of Cambridge, England, who co-study studies.
The study, published in the journal Royal Society B, combines field records of Bolivian rainforests with laboratory experiments and computer simulations to understand how these extraordinary sounds are produced.
The researchers documented the call of several monkey species, including the black and golden how called monkey, the tufted capuchin monkey, the black squirrel monkey and the Peruvian spider monkey. They found that monkeys suddenly folded the production of sound from their vocal cords to thin ribbon-like structures called vocal membranes, which create unique sound interruptions that sit above the folds of vocals in their throats.
Unlike human Yodeling, which usually spans one octave or less, some monkey calls recorded show a frequency jump of up to twelve times – equivalent to three and a half octave jumps in a single vocal. For comparison, it is like the human singer jumping immediately from the bass note to the highest note of the soprano, which is impossible for human vocal cord anatomy.
“This is a fascinating example of how nature provides the means of animals to make sound despite their lack of language,” said Christian T. Herbst of the University of Vienna, the study’s lead author. “The generation of these complex sound patterns is achieved primarily through the anatomical shape of animals and does not require complex neural controls generated by the brain.”
To prove their theory about how these sounds are produced, scientists conducted experiments with the excision of monkey throat and created computer simulations that successfully reproduced the unique vocal pattern.
Studies show that monkeys, a New World extending from Mexico to Argentina, have developed the largest sound membranes of all primates. These thin tissue expansions may play a crucial role in enriching sound repertoire, potentially helping them convey complex messages among social groups.
Professor Tecumseh Fitch, an expert in vocal evolution at the University of Vienna, explained: “Our study shows that vocal membranes expand the tone range of monkeys, but also destroy their voices. They may have been lost during human evolution to promote tonal stability in singing and speaking.”
This evolutionary trade-off shows that while humans gain more stable and controlled sounds of speech, we lose the ability to produce extreme sound gymnastics retained by primate relatives.
These findings provide valuable insights into the communication of primates and the evolution of human speech. They also show that the complexity of monkey calls may be related to brain complexity and more to smart anatomical adaptations.
“This is especially important in primates with complex social life and require communication in many different ways,” Dr. Dunn noted. “It is likely to evolve to enrich the animal’s call repertoire and potentially used to draw attention to change, call for diversity or identify oneself.”
So the next time you hear the impressive alpine Yodeler, remember that in the rainforest of Latin America, monkeys are performing vocal feats that make human Yodeling look like a child’s game – thanks to a small piece of tissue lost in our speech evolution journey.
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