Humans are uniquely capable of complex spoken language, prompting curiosity about our closest relatives, the great apes, and why they do not speak like humans. The primary answer lies in specific human biological adaptations, absent in gorillas, affecting their vocal anatomy and brain’s capacity for language processing.
Anatomy of Vocal Production
Producing a wide range of speech sounds relies on a specialized vocal apparatus that differs significantly between humans and gorillas. A key distinction lies in the position of the larynx, or voice box. In humans, the larynx is situated much lower in the neck compared to other primates, including gorillas. This descended position creates a larger pharyngeal cavity (the space above the vocal cords) that acts as a resonating chamber, allowing for the manipulation of sounds into distinct vowels and consonants.
The human tongue is more flexible and muscular, enabling precise movements essential for shaping airflow into varied speech sounds. The soft palate, at the back of the mouth, controls whether air flows through the mouth or nose. Humans can rapidly adjust it to produce non-nasal sounds, a control not seen in gorillas. These anatomical differences give humans a unique vocal tract capable of intricate speech sound production.
Brain and Language Processing
Beyond anatomy, the human brain’s neurological architecture for language processing differs from gorillas’. While gorillas possess cognitive abilities like problem-solving and memory, their brains lack the specialized structures and neural pathways for complex human linguistic functions.
The human brain features highly developed regions such as Broca’s area (frontal lobe), involved in speech production, articulation, and grammar. Wernicke’s area (temporal lobe) is essential for language comprehension. These areas are interconnected by the arcuate fasciculus, facilitating communication between production and comprehension centers.
The human brain’s capacity for symbolic thought and vocal coordination for speech is wired through these networks. Gorillas lack this level of development or specialization in these regions, contributing to their inability to process and produce human language. The human brain is about three to four times larger than a gorilla’s, with a significantly higher number of cortical neurons, particularly in the frontal lobes and neocortex.
Gorilla Communication Systems
Despite their inability to produce human speech, gorillas communicate effectively. They use vocalizations like grunts, hoots, screams, and roars to express emotions and coordinate group activities. Silverbacks often belch to convey satisfaction, while infants use whimpers and cries to attract their mothers’ attention.
Beyond vocalizations, gorillas rely on body language, including postures, gestures, and facial expressions, to convey messages. Chest-beating signals aggression or dominance, with sound carrying over long distances due to large air sacs in males’ chests. While these systems are complex and functional for social interactions, they differ from human spoken language in structure and capacity for conveying abstract ideas.
However, studies involving gorillas like Koko and Michael show their cognitive capacity for symbolic understanding. They successfully learned and used American Sign Language, with Koko acquiring over 1,000 signs and understanding 2,000 spoken English words. This demonstrates their intelligence and ability to learn symbolic communication, even if their vocal anatomy prevents them from producing human speech.