In response to @Lcs 's recent comment: There's 5 different sources of ethical standards: utilitarian, rights, fairness/justice, common good, and virtue. So on the subject of comparing "bestiality = rape" when "killing =/= murder", it's worth mentioning that you're trying to compare the ethical conclusions for two different ethical justifications. Apples and oranges, basically. But let's clear things up. So for each of those five ethical standards considered, determining right from wrong, ethical vs unethical, depends on the answers to these 5 questions: 1) Which option will result in the most good, and do the least amount of harm? (Utilitarian) 2) Which option ensures that everyone's rights are considered and respected? (Rights) 3) Which option best serves the community, or as many as possible, as opposed to just one entity, or only a handful of people? (Common Good) 4) Which option will treat everyone with equality, equity, respect, and fairness? (Justice) 5) Which option will ensure I act as the ideal person I wish to be, or that my community/culture/religion wishes me to be? (Virtue) Killing animals for food and resources comes from a solely Utilitarian standpoint. Animals kill other animals, and we don't refer to a puma killing a deer as murder. However, we refer to chimpanzees killing other chimpanzees as murder; in this instance, murder is an act of aggression against one's own kind. It's an act of being traitor to the survival of one's own species. Additionally, most human cultures and laws also do not classify killing other humans in self-defense as murder, or classify chimpanzees murdering chimpanzees as a punishable criminal offense under human law, because it would not be useful to do so and the drawbacks would outweigh the benefits. If approached from the Rights standpoint, it is argued by many that while animals do not have the same legal rights as humans, they should still be respected as living creatures; but then the definition of "respect" becomes grey, as some people interpret that to mean "no killing sentient creatures whatsoever", and others will say that a swift and painless death preceded by a well-fed and well-groomed life on an open farm is respectful. Your mileage may vary. But murder of another human is taking away their right to live; animals are not granted with the inherent "right to life", which is an entirely human social construct (nature does not grant a "right to life" for anything), and that right is administered and withdrawn by human society as it sees fit. And so you can't take away rights that they don't already have. From the Common Good standpoint, many people love to eat animals, and people who own carnivorous pets such as cats and dogs that require a diet of meat to survive. So killing chickens, cows, pigs, and other domesticated livestock benefits millions of people, despite the loss of life. But if someone is hunting just for fun, that is for their own selfish benefit and enjoyment, at the cost of a suffering animal. When humans of an impoverished country want a selfish dictator overthrown, and they plot for his death, the common good and potential benefits outweighs the cost of killing the dictator, and as such is not classified as murder. From the Justice standpoint, some animal rights activists would argue that animals should be treated equally to humans, while others such as PETA believe that they should live independently of humans with no interaction whatsoever. Again, your mileage may vary depending on your definitions of "justice" and "equality", which are super subjective and vague terms when it comes to actually providing concrete results. And lastly is Virtue. It may be against your community rules, culture, or religion to kill anything whatsoever, or perhaps only a few animals such as cows, dogs, or cats are off-limits. This is just based entirely on upbringing and tradition. Or perhaps your culture requires you to go out and kill a lion to become a man. Virtue is probably the most subjective form of ethical decision making of them all. Most major cultures and religions tend to have this common agreement that killing your fellow humans is punishable, but killing animals is acceptable. So now that we covered killing vs. murder, go back and notice how in every instance there is a different result as to whether something is considered ethical or not, whether or not something is considered killing or murder, and why. Now apply the same logic to bestiality and why it might not be the exact same crime as rape, but might be classified as such under the Rights standpoints and Virtue standpoints, and still falls under the "unethical" categories on the other three potential justifications. And also look at the topic of human castration vs. animal neutering/spaying under that lens to see how they compare.