Species purity alarm: David Cameron and the pig's head

Bestiality, however, is still not a topic that is openly discussed or deemed appropriate for even mainstream erotic fiction. Much less a politician's dirty laundry.

The reaction on Twitter to the pig's head allegations reveals one overwhelming fact – people find the idea of sex acts with a pig hilarious. According to The Conversation, one reason why #piggate played so well on Twitter is that making jokes about David Cameron and pigs allows us to turn the tables on the privileged and powerful.

However, while this may be the case, the humor is revealing in that it mostly speaks to our use of the pig as a product of consumption, or one that is in someway 'unclean'. The Tweets may joke that we can no longer really trust where our bacon comes from, but none mention just how smart pigs are. A paper published in the latest issue of the International Journal of Comparative Psychology reveals that pigs have been found to be mentally and socially similar to dogs and chimpanzees.

In an age of biotechnology and genetic manipulation, the possibilities for the merging of the human and the animal can now occur at a molecular level. From pig cell insulin to transgenic animal organ transplants and chimerical eggs that are almost human, the boundary between the human and the animal is becoming increasingly blurred.

Historically, human society has evolved in close proximity with animals, and it is therefore not surprising that our myths, folklore and fiction have embraced the animal and our relationship with it. Fantastic beasts intertwining the human and animal are part of the history of the human imagination, in spite of the strongly enforced distinction between human and animal.

In the 21^st century, however, the primary socially acceptable literary outlet for this taboo is in "fantasy bestiality", featuring mythical beasts such as dragons and satyrs. Paranormal genres allow readers to indulge in bestial sexual fantasies that are unspeakable within the wider community. These manifestations of bestiality do not entail a wider acceptance of these practices. According to Susan Squier "xenogenic desire" between species in literature can give expression to desire while simultaneously deauthorising it as 'only fiction'.