This haunts me. Gorillas and chimps are crazy smart and can be taught sign language, so why can’t they speak? They have human-like mouths and they’re obviously vocal, so why don’t they at least have the vocabulary of a toddler?
In:
Humans have genetic differences that essentially allow us to vocalise and breathe at the same time. I think there was a chimp who managed a few words at a time but its not usual, they don’t have the correct structures. Puts us at the top of the list of animals most likely to choke but being able to communicate complicated ideas vocally is a huge competitive advantage
No one mentioned the hyoid bone. The hyoid bone is a horseshoe shaped bone that is located under your tongue, close to your lower jaw. It is the only bone in the human body that is not connected to other bones, and is only connected to muscles. The hyoid bone attaches to your tongue, and allows for very precise control over the tongue muscle. This fine manipulation is a big part of why speech is possible.
Other apes have a hyoid bone, but it is shaped differently. The hyoid in other apes is located *behind* the root of the tongue muscle, and so it doesn’t allow for the same range of tongue movement as it does in humans. Additionally, it’s postulated that the hyoid bone prevents other apes from closing off their airway using their tongue muscle the way that humans do. Think of the word “hung”. That “ng” is caused by closing off your airway in your throat.
The last thing that I will mention is the amount of nerves controlling the tongue, lips, and cheeks. In humans and apes nerves pass through a vertebra at the top of the spine. In humans, the opening is proportionally much larger than it is in other apes, which suggests that humans have more motor neurons controlling the tongue, cheeks, and lips – the muscles used for speech.
Edit: a couple sources [1](https://carta.anthropogeny.org/moca/topics/hyoid-bulla) [2](https://www.livescience.com/7468-hyoid-bone-changed-history.html)
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