Charles Darwin could speak other languages

Language acquisition: So spoke the monkey

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Plan a longer stay with the macaques on your next visit to the zoo. Talk well to the monkey of your choice. Perhaps you will pique his interest. It may even come over to the pane or the grille. And possibly, with a lot of luck, it will answer you: "Listen to me, Kleener! Are you always chattering?"

Admittedly, that is unlikely to happen. Just why not? The debate has been going on since Charles Darwin. Can't monkeys speak because their brains can't - or because their physique doesn't allow them to? A new study by the evolutionary biologist Tecumseh Fitch, who lectures in the Faculty of Cognitive Biology at the University of Vienna (Science Advances: Tecumseh Fitch et al., 2016). In this, the researchers break with a decades-old hypothesis.

The language barrier

For since 1969, behavioral research has dominated a doctrine based on the work of the American Philip Lieberman. The cognitive scientist was one of the first to bring study-based findings into the discussion.

At that time, Lieberman and colleagues made a plaster cast of the throat and speech apparatus of a deceased rhesus monkey, a species of macaque. Building on this, they developed a computer model that simulated what sounds the monkey could make with its organs. The researchers compared these phonetic possibilities with those of humans and came to the conclusion that monkeys cannot make sounds that resemble human speech because their larynx is not deep enough to do this (see box). From then on, what sometimes matures into a pronounced Adam's apple was considered a milestone in human evolution. The deep larynx made people human. It was only thanks to him that he could speak.

Language of the apes

Lieberman's larynx problem

The larynx of monkeys is much higher than that of humans - at least in adults. This gives toddlers and primates the advantage of being at the same time swallow and breathe can.

To speak is a deep larynx but more practical: It allows you to form various sounds in cooperation with the tongue, palate and the right breathing. The downside of the gossip: people choke more easily.

Linguist Philip Lieberman came to the conclusion after computer simulations in the late 1960s that this larynx problem was the main reason why monkeys could not speak. Viennese researchers are now contradicting precisely this claim. After all, the monkeys made sounds in their computer simulations.

Zoological voice-over

But Lieberman's approach was not enough for the Viennese researchers. After all, the test monkey was already dead. The plaster cast did not show how the macaques' speech apparatus was used. So the biologists decided to watch live animals "talk" - this time crab-eating macaques, close relatives of Lieberman's rhesus monkeys. Using x-rays, they determined how the tongue, throat and throat changed as soon as the macaques were ready to make a sound. But that was still not enough for the scientists.

The ape language repertoire only represented what the crab-eating monkeys were doing - not what they were capable of. So the researchers also scanned the animals while they raised their lips, made faces or yawned. So the biologists included facial expressions. Their theory: If the rhesus monkeys are capable of these changes, then they could also generate the corresponding sounds with the appropriate air expulsion.