Whether they are long and slimy, wide and bumpy, fissured, furry or tied – our tongues may be even more unique than we give them credit for. An analysis of 3D images of human tongues suggests that each of us may have a unique “tongue print” just as we have individual fingerprints. The research could help to shed new light on why people’s food preferences can be so varied, and assist in the design of healthier, yet delicious, alternatives to fatty or sugary foods. Averaging about 10cm in length, with only the front two-thirds visible, our tongues are complex and sophisticated organs, covered in hundreds of small buds, known as papillae. Some of these projections hold our tastebuds, whereas others enable our tongues to sense texture, friction, lubrication and touch. “These sensory functions are critical for manipulation and transport of food and liquids in the mouth,” said Rayna Andreeva, a PhD student at the University of Edinburgh, who led the research. They may also influence our psychological reactions to food – for example, how satisfied we feel after eating appears to be influenced by our perception of friction and lubrication, as does our preference for certain foods such as chocolate. But while the taste function of papillae has been well researched, far less is known about the differences in shape, size and pattern of papillae between individuals. To investigate, Andreeva and colleagues trained AI computer models to learn from thousands of microscopic scans of individual papillae, taken from silicone moulds of 15 people’s tongues, mapping their size, features and location on the tongues’ surfaces. The research, published in the journal Scientific Reports, found that a single papilla could predict someone’s gender and age with moderate accuracy, up to 67%-75%, and even the specific individual could be identified from the 15 study participants with about 48% accuracy (a random predictor would have an accuracy of just 6.66%). While further studies are needed to confirm this in larger numbers of people, the study provides some of the first evidence that tongue papillae could act as a unique identifiers, the authors said. “We were surprised to see how unique these micron-sized features are to each individual,” said senior author Prof Rik Sarkar at the University of Edinburgh. Studying how the distribution of papillae varies across individuals and populations could provide new insights into why certain people or groups like some foods more than others, and how tongue features correlate with various medical conditions. The research could also aid the design of personalised foods. Sakar said: “Imagine being able to design food customised to the conditions of specific people and vulnerable populations and thus ensure they can get proper nutrition whilst enjoying their food.” For instance, he said, a better understanding of the physical mechanisms that happen when different people eat chocolate could lead to alternatives that offer a similar feel and sensation but with a lower fat content.