Melatonin: The Ancient Molecule That Connects All Life on Earth

Why Do All Living Things From Bacteria to Humans Make Melatonin?

Melatonin is one of the most ancient molecules on Earth, evolving billions of years ago in primitive bacteria as a powerful antioxidant to protect against the toxic effects of oxygen. This universal molecule has been preserved throughout evolution because it serves fundamental protective functions - from neutralizing free radicals in bacterial cells to regulating sleep cycles in modern humans, making it a molecular link that connects all life on our planet.

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How Uric Acid Shaped Human Evolution and Fuels Hypertension Today

Dr. Kumar’s Take:

This study reveals something fascinating: a mutation millions of years ago raised uric acid levels in our ancestors, helping them maintain blood pressure when dietary salt was scarce. That survival tool has now turned into a vulnerability. In today’s high-salt world, the same elevated uric acid contributes to salt-sensitive hypertension, kidney damage, and heart disease.

Key Takeaways:

✔ Humans lost uricase, the enzyme that lowers uric acid, during the Miocene era.
✔ Higher uric acid helped maintain blood pressure in low-salt diets but now drives hypertension.
✔ Animal studies show uric acid directly raises blood pressure by activating the renin-angiotensin system and damaging kidney vessels.
✔ Modern high-salt diets make this ancient adaptation harmful.

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Why Humans Lost Uricase: Evolution, Uric Acid, and Health Implications

Dr. Kumar’s Take

This study dives into the mystery of why humans and our closest primate relatives lost the enzyme uricase, which normally breaks down uric acid. The research shows that independent mutations in different ape lineages disabled this gene. As a result, humans have much higher uric acid levels compared to most mammals. While this may have offered evolutionary advantages like antioxidant protection for the brain and longer lifespan, it also increased our risk for gout and kidney disease. For modern readers, the study highlights why maintaining healthy uric acid levels is so important.

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Why Humans Lost Uricase: Evolutionary Insights from Ancient Enzymes

Dr. Kumar’s Take

This study used a fascinating approach called ancestral sequence reconstruction to “resurrect” ancient versions of uricase, the enzyme that breaks down uric acid. What they found was that uricase did not suddenly disappear in humans and apes. Instead, it weakened step by step across millions of years before finally being shut down. This gradual loss likely helped our ancestors survive by storing more fat from fruit sugar (fructose) during times of food shortage. But today, that same genetic change contributes to high uric acid levels, gout, obesity, and metabolic disease.

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