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A Biologist Explains Why Humans Have Lips (Hint: No Other Primate Has Them)
Forbes • • general
Key Points:
- Human lips are unique among living hominids due to the outward-facing vermilion border, a band of moist tissue exposed to the air, which is absent in chimpanzees and other primates.
- The red color of human lips is caused by thin skin revealing blood vessels underneath, but this thinness also makes lips vulnerable to drying and sun damage, suggesting an evolutionary trade-off.
- Three main theories explain the evolution of human lips: aiding infant nursing with a flat breast, facilitating speech articulation, and serving as social and sexual signals through visible color changes.
- Lips did not evolve specifically for kissing, as romantic kissing is absent in many cultures; instead, lips play a complex role in eating, speaking, tactile sensation, and social communication.
- The brain dedicates a large sensory area to the lips, highlighting their importance in touch and exploration, especially in infancy, indicating multiple overlapping functions behind their evolutionary development.
