A common question is whether apes possess vocal cords similar to humans. Apes, our close evolutionary relatives, communicate through various sounds, prompting curiosity about the biological structures behind their vocalizations. Understanding their anatomy helps explain why, despite many biological similarities, apes do not produce human-like speech.
Ape Vocal Anatomy
Apes possess vocal cords, folds of tissue within the larynx. This structure sits at the top of the trachea. Sound production is similar across many mammals, including apes and humans: air from the lungs passes through the vocal cords, causing them to vibrate and generate sound.
These vocal folds are composed of mucous membrane and muscle fibers, including the vocalis muscle. Their vibration rate determines the sound’s pitch. While the underlying principle of sound generation is shared, apes also have additional structures not found in humans, such as vocal membranes and laryngeal air sacs.
Vocal membranes are small, ribbon-like extensions of the vocal cords in most non-human primates. They contribute to loud, high-pitched calls and can make vocalizations more unstable. Laryngeal air sacs are balloon-like out-pouchings from the larynx, also found in many apes. Their precise function is still being investigated, but they are thought to amplify calls and possibly prevent hyperventilation during intense vocalizations.
Why Apes Don’t Speak Human Language
Despite having vocal cords and a larynx, apes cannot produce human speech due to differences in their vocal anatomy and neurological control. A significant anatomical distinction is the larynx’s position. In apes, the larynx is higher in the throat compared to humans. This higher placement results in a shorter pharynx, the part of the throat above the larynx, which limits the range of sounds that can be produced.
The structure and mobility of the tongue also differ. Human tongues are more flexible and precise, allowing for rapid shaping of the vocal tract necessary for diverse speech sounds. An ape’s tongue is less flexible, restricting its ability to modify sounds. The overall shape of the ape vocal tract, influenced by the higher larynx and less mobile tongue, does not allow for the full range of vowel and consonant sounds.
Beyond anatomical differences, neurological factors play a substantial role. While apes possess some brain regions homologous to human language centers, these are not developed or specialized for complex language processing and fine motor control of the vocal apparatus. Humans have direct neural pathways from the motor cortex to the muscles controlling the larynx and mouth, enabling precise and voluntary control over speech articulation. Apes lack these specialized neural pathways, limiting their voluntary control over vocalizations. The ape vocal tract may be “speech-ready,” but their brains lack the necessary circuitry for producing human-like speech.