Zoophilia is a paraphilia in which a person experiences a sexual fixation on non-human animals. Bestiality instead refers to cross-species sexual activity between humans and non-human animals. Because of the lack of research on the subject, it is difficult to conclude how prevalent bestiality is. Zoophilia on the other hand, was estimated that to be prevalent in 2% of the population in 2021. The historical perspective on zoophilia and bestiality varies greatly, from the prehistoric era, where depictions of bestiality appear in European rock art, to the Crow and Ojibwe tribes where bestiality was a historically accepted practice, to the Middle Ages, where bestiality was met with execution. In many parts of the world, bestiality is illegal under animal abuse laws or laws dealing with sodomy or crimes against nature. Terminology General Three key terms commonly used in regards to the subject—zoophilia, bestiality, and zoosexuality—are often used somewhat interchangeably. 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. Some studies have found a preference for animals is rare among people who engage in sexual contact with animals. Furthermore, some zoophiles report they have never had sexual contact with an animal. People with zoophilia are known as "zoophiles", though also sometimes as "zoosexuals", or even very simply "zoos". Zooerasty, sodomy, and zooerastia are other terms closely related to the subject but are less synonymous with the former terms, and are seldom used. "Bestiosexuality" was discussed briefly by Allen (1979), but never became widely established. Ernest Bornemann coined the separate term zoosadism for those who derive pleasure – sexual or otherwise – from inflicting pain on animals. Zoosadism specifically is one member of the Macdonald triad of precursors to sociopathic behavior. Zoophilia The term zoophilia was introduced into the field of research on sexuality in Psychopathia Sexualis (1886) by Krafft-Ebing, who described a number of cases of "violation of animals (bestiality)", as well as "zoophilia erotica", which he defined as a sexual attraction to animal skin or fur. The term zoophilia derives from the combination of two nouns in Greek: ζῷον (zṓion, meaning "animal") and φιλία (philia, meaning "(fraternal) love"). In general contemporary usage, the term zoophilia may refer to sexual activity between human and non-human animals, the desire to engage in such, or to the specific paraphilia (i.e., the