Evolution of an Idea

A timeline of thoughts on animals

Questions about our relationship with and responsibility toward other animals have always been troubling. The elaborate rituals of Judaism’s kosher rules and Islam’s halal, for example, may have started as a way of atoning for the act of murder. The development of a coherent animal rights philosophy has been unsteady, with setbacks and reversals accompanying each attempt at more enlightened thinking.

artwork depicting an animal in a courtroomWikimedia CommonsAn 1838 painting by P Matthews of the Trial of Bill Burns, the first prosecution under the 1822 Martin’s Act for cruelty to animals in England, after Burns was found beating his donkey. The case became memorable because the donkey was presented in court.

570 – 400 BCE

Hindu, Jain and Buddhist philosophies preach ahimsa, or nonviolence toward all animals, based on the thought that all living beings are part of one interconnected, divine soul. To this day, some Jain ascetics cover their mouths and sweep the ground in front of them while walking in order to avoid hurting crawling insects and flies.

The Greek philosopher and mathematician Pythagoras (570 BCE), who is said to have heard the cry of a dead friend in the bark of a dog, says animals, like humans, had souls. He is one of the earliest Western campaigners for ethical vegetarianism. In fact, vegetarians were referred to as “Pythagorean” as recently as the nineteenth century.

Aristotle (384–422 BCE) argues that animals are inferior to humans because they can’t reason, and that nature created them to serve our needs. He denies moral status to women and slaves as well.

600 ACE

Prophet Mohammed, founder of Islam, proclaims: “A good deed done to an animal is as meritorious as a good deed done to a human being, while an act of cruelty to an animal is as bad as an act of cruelty to a human being.”

12th Century

The Soto Zen school of Buddhism institutes the requirement of a vegan diet. The practice is still followed by many Zen practitioners.

13th Century

Catholic theologian Thomas Aquinas uses a mix of Aristotelian and Christian thought to place man at the center of all creation and says we should be considerate toward animals only because it teaches us to be charitable toward other humans. Prior to Aquinas, most Christian orders followed vegetarian or partially vegetarian diets in keeping with the dictates of St Benedict and included animals in church services.
In the Americas, many Indigenous cultures recognize only a thin line between the “two-leggeds” and the “four-leggeds” and consider animals as messengers from the spirit world. In California, the Miwok think of the coyote as their ancestor, while the Lakota of the Great Plains call themselves the “Buffalo People.”

17th Century

French philosopher René Descartes asserts that animals are like unconscious automatons that function in sophisticated ways but have no thoughts and can’t feel pain. To test his theory, Descartes nails his wife’s dog to a board and chops it open while still alive.

German philosopher Immanuel Kant, like Aristotle, posits that the only reason we should avoid being cruel to animals is that in doing so we might develop cruel habits that we would inflict on other people. This kind of thought underpins much of the animal protection legislation that exists today.

18th Century

English social reformer Jeremy Bentham is among the first to equate animal captivity to slavery. In 1789 he writes: “The question is not, ‘Can they reason?’ nor, ‘Can they talk?’ but ‘Can they suffer?’”

English naturalist Charles Darwin’s theory of evolution by natural selection upends thinking about man’s relationship with other species. He argues that not only do animals have a direct kinship with humans, but that they have social, mental and moral lives, too.


British psychologist Richard Ryder coins the term “speciesism” – which he defines as the false idea that being human is a reason enough for us to have greater moral rights than non-humans. He equates it to the same sort of bigotry as racism or sexism.

Peter Singer publishes Animal Liberation, the bible of the modern animal rights movement, which argues, echoing Bentham, that all animals who feel pain deserve moral consideration.

You Make Our Work Possible

You Make Our Work Possible

We don’t have a paywall because, as a nonprofit publication, our mission is to inform, educate and inspire action to protect our living world. Which is why we rely on readers like you for support. If you believe in the work we do, please consider making a tax-deductible year-end donation to our Green Journalism Fund.

Get the Journal in your inbox.
Sign up for our weekly newsletter.

Subscribe Now

Get four issues of the magazine at the discounted rate of $20.