Crocodile tears are real and could revolutionize how we treat dry eyes

Science · Published 8 October 2026 Swipe more like this →

In short: The phrase "crocodile tears" implies a fake display of emotion, but for these reptiles, the fluid is very real. Beyond just being a figure of speech, these biological secretions might hold the secret to stabilizing the human eye and treating chronic dryness.

While humans are the only species known to produce emotional tears, the physical liquid itself serves vital biological functions across the vertebrate tree of life. In humans and several mammals, tears form a protective film composed of three essential ingredients: mucus to bind the film to the eye, water acting as a saline solution with proteins and minerals, and oil to prevent evaporation. This film is vital for vision, as it lubricates the eye, clears debris, and provides nutrition to the cornea, which lacks its own blood vessels.

Recent research led by veterinarian Arianne Pontes Oriá at Brazil’s Federal University of Bahia has expanded our understanding by analyzing tears from reptiles and birds for the first time. While scientists previously focused on mammals like dogs, horses, and monkeys, Oriá’s team examined species such as barn owls, blue-and-yellow macaws, and broad-snouted caimans. A striking discovery was the diversity in how these tears crystallize, with patterns varying significantly between species.

The study holds significant potential for human medicine. For example, broad-snouted caimans can keep their eyes open for up to two hours without blinking, yet their eyes do not dry out. Understanding the specific molecules that provide this level of stability to the tear film could lead to advanced treatments for human eye diseases and dry eye syndromes. By studying how evolution has tinkered with these fluids to suit different environments, researchers hope to find new ways to maximize ocular health.

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