An antler-less ancestor
The Korean water deer (Hydropotes inermis argyropus) represents an early branch of the deer family tree. Unlike nearly all other members of the family Cervidae, males do not grow antlers. Instead, they possess a more primitive feature: elongated upper canine teeth that grow into sharp tusks. These saber-like fangs are a relic from antlerless, tusked ancestors that lived millions of years ago. While female water deer have very small canines, a male's tusks are formidable weapons, averaging 5.5 centimeters (2.2 inches) in length and capable of reaching up to 8 centimeters (3.1 inches). The teeth erupt when the deer is about six to seven months old and are fully developed by the age of two.
These tusks are not fixed in place. The deer can control their position with facial muscles, drawing them backward when eating. This anatomical detail distinguishes them from many other mammals with large canines. The deer's skull structure supports these unique teeth, which are used exclusively for combat between territorial males. Gyeonggi Province, with its mix of wetlands, river basins and low hills, provides an ideal habitat for these animals, which prefer areas with tall reeds and grasses for cover. South Korea hosts an estimated 700,000 water deer, making it the world's largest population and a unique location for observing this evolutionary divergence.