Study Links Human Joint Degeneration to Evolutionary Trade-offs
Researchers from Japan and Israel suggest that lower levels of cartilage-building sugars in humans may be an evolutionary compromise that enables a more adaptable brain and lighter skeleton for endurance running.
Scientists from Japan and Israel have published a study in Nature proposing that humans' susceptibility to arthritis stems from an evolutionary sacrifice. Their genetic analysis shows humans synthesize considerably fewer glycosaminoglycans (GAG) than our closest primate relatives, leading to thinner cartilage that rubs against bone and triggers joint wear. The same deficiency appears in the brain, where reduced GAG levels may keep neural tissue more malleable for extended developmental windows, supporting advanced skill acquisition.
The researchers also note that a lighter, less robust skeleton could have given early humans an advantage in endurance running, aiding food gathering and hunting. Together, these factors suggest that the price of enhanced cognition and mobility is a higher incidence of joint disease in later life.
Why it matters
Understanding the evolutionary roots of arthritis could guide new treatments and inform how lifestyle choices affect joint health.
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