Some studies have found a preference for animals is rare among people who engage in sexual contact with animals. Some researchers distinguish between zoophilia (as a persistent sexual interest in animals) and bestiality (as sexual acts with animals), because bestiality is often not driven by a sexual preference for animals. Three key terms commonly used in regards to the subject- zoophilia, bestiality, and zoosexuality-are often used somewhat interchangeably. In many parts of the world, bestiality is illegal under animal abuse laws or laws dealing with sodomy or crimes against nature. The historical perspective on zoophilia and bestiality varies greatly, from the prehistoric era, where depictions of bestiality appear in European rock art, to the Middle Ages, where bestiality was met with execution. Zoophilia on the other hand, was estimated that to be prevalent in 2% of the population in 2021. Because of the lack of research on the subject, it is difficult to conclude how prevalent bestiality is. Bestiality instead refers to cross-species sexual activity between humans and non-human animals. Zoophilia is a paraphilia in which a person experiences a sexual fixation on non-human animals. Roman oil lamp dating from 1st–3rd century A.D. A kylix depicting Silenus having sex with a fawn, dated after 500 BC.