The evolution of speech is closely tied to changes in the human vocal tract. These anatomical modifications enabled a greater range of sounds, facilitating the development of complex spoken language. Key changes include:
- Lowered Larynx – In humans, the larynx sits lower in the throat than in other primates. This creates a larger pharyngeal cavity, allowing for a greater variety of vowel sounds, which is crucial for speech clarity.
- Increased Oral Cavity Flexibility – The tongue in humans is more agile and can move freely within the oral cavity, enabling precise articulation of consonants and vowels.
- Shortened Muzzle and Retracted Face – Compared to other primates, humans have a flatter face and a shorter oral cavity, which improves articulation and resonance.
- Differentiation of Vocal Tract Lengths – The ratio of oral to pharyngeal cavity length in humans allows for a wider range of formants (resonant frequencies), improving speech distinctiveness.
- Refined Neural Control – The motor control of the tongue, lips, and vocal cords became more intricate over time, enabling nuanced speech sounds.
These vocal tract changes, combined with cognitive and social evolution, laid the foundation for spoken language, distinguishing humans from other primates.