Usually, the upper first molar teeth have four cusps, looking like horns. Cusps help the teeth to pierce and crush food, and prevent prey or food from slipping away.
Some people have upper molar teeth with an extra cusp on the palatal side (near the tongue). The cusp on the palatal side is called the cusp or tubercle of Carabelli; if they are present, the tubercles are usually found on the first molar, and less commonly in the second or third molar. The tubercle of Carabelli is most common among Europeans, less common among Asians, and least common among Pacific Islanders. This fact allows the forensic odontologist to narrow down the search for the ethnicity of the victims of disasters or unnatural deaths, and helps the paleontologist to determine the migration pattern of early human inhabitants.