Human tooth sensitivity linked to sensory tissue in ancient armored fish, new study suggests
CHICAGO: In a surprising new study published in Nature, researchers at the University of Chicago have traced the origins of modern human tooth sensitivity to sensory tissues in the bony armor of ancient fish that swam Earth's oceans over 485 million years ago.
The research was led by Dr. Yara Haridy, a postdoctoral researcher working in the renowned lab of evolutionary biologist Dr. Neil Shubin. Together, they discovered that dentine—the sensitive inner layer of human teeth—likely evolved from similar tissue found in the exoskeletons of long-extinct marine animals from the Cambrian period.
Why ancient fish armor matters today
Dentine is the part of a tooth responsible for transmitting sensations such as pain and temperature through microscopic tubules that connect to nerves. But this tissue may have served a different purpose millions of years ago.
“This shows us that ‘teeth’ can also be sensory even when they’re not in the mouth. There’s sensitive armor in these fish. There’s sensitive armor in arthropods. This helps explain the confusion with these early Cambrian animals,” said Dr. Haridy.
Using advanced CT scanning and comparative analysis, Dr. Haridy studied hundreds of fossilized remains. One fossil, initially believed to belong to the earliest vertebrate known as Anatolepis, was reclassified as an arthropod based on its structural similarity to sensilla—sensory organs found in insects and crustaceans.
From sea creatures to toothaches
The team’s findings suggest that in the harsh, predator-filled oceans of the Cambrian period, ancient fish relied on their armored exoskeletons not only for protection but also for environmental awareness—similar to how we now rely on our teeth’s sensitivity to avoid harm.
“When you think about an early animal like this, swimming around with armor on it, it needs to sense the world. This was a pretty intense predatory environment. Being able to sense the properties of the water around them would have been very important,” explained Dr. Shubin.
The evolutionary repurposing of dentine from external armor to internal dental tissue offers a rare glimpse into how complex biological structures adapt over millions of years. This research bridges paleontology and human biology, providing valuable insights into why tooth sensitivity remains a common condition today.
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