Human societies can pride themselves on waging wars against several forms of prejudice - racism, sexism and the caste system to name a few. But this record is blemished - not just by bigotry repeatedly rearing its ugly head, reminding us of the work left to be done, but also by the refusal to recognise our attitudes to nonhumans as a form of prejudice no less objectionable than those aforementioned. While a few advances have admittedly been made - some countries have enacted legislation to prevent and penalize animal abuse - the vast majority of our species is yet to view our treatment of animals as intolerable.

If humans feel justified to exploit nonhumans simply because of differences in species, their stance is analogous to racists and sexists who think that whites and males have a superior status. Although most humans may possess higher reasoning and intellectual abilities, that does not justify the distinction we make between humans and animals. Some people - infants and severely intellectually disabled - have mental capabilities inferior to many animals. But no one would argue in favour of inflicting torture and death on them in order to test the safety of makeup products. Nor would anyone propose that we butcher them for a scrumptious dinner. The fact that we do not extend moral equality to nonhumans makes us guilty of a form of bigotry that philosophers call speciesism - the belief that members of a certain species have greater moral rights than others.

It is the breeding of animals for consumption that is at the heart of our speciesist attitudes towards them. Every year, several billion sentient creatures are slaughtered to satisfy our taste for their meat. An estimated 50 billion chickens are killed for food every year – a figure that excludes the hundreds of millions of male and imperfect female chicks that are asphyxiated in gas chambers dropped into automatic shredders or simply thrown into the rubbish in commercial hatcheries. Nearly 1.5 billion pigs are butchered to meet the growing appetite for pork, bacon, ham and sausages. Half a billion sheep are taken to the abattoir every year. Most of these animals are raised in factory farms, where they are crammed into tiny spaces, and given little to no fresh air, sunlight or access to the outdoors. Pregnant cows and sows are kept confined in gestation crates which barely allow them space to turn around or sleep on their side. Their offspring are forcibly weaned and separated from them at a very young age and shipped to be fattened and slaughtered. Turkeys and chickens have been selectively bred to become so large that they can hardly walk around. These table birds are often reared in crowded sheds, inside which all their natural activities are frustrated, and they develop aggressive behaviours such as pecking each other to death. To prevent this, their beaks are mutilated and sheds are kept dark.

Speciesism also becomes apparent in the practice of conducting experiments on animals. While some of the cruellest and most infamous experiments, like vivisection, LD50 and the Draize test have been outlawed by many countries, pharmaceuticals and cosmetics continue to be majorly tested on animals before they are approved and released in the market. Each year, more than 110 million animals are killed in US laboratories alone. But researchers are increasingly finding that an overwhelming number of animals, particularly mice, are being sacrificed for studies that are too small to be meaningful and are often poorly designed. The results of many other studies are trivial and obvious. Furthermore, several drugs tested in mice fail in human clinical trials because mice are poor substitutes for human physiology. Many of these trials, which subject thinking and feeling beings to excruciating pain and even death, are publicly funded.

Given that animals have the capacity to feel pain and distress, and conversely, to have self-awareness and enjoy life, the case for continuing to treat them as a means to our ends cannot be maintained. There is a pressing need to expand moral consideration to nonhuman beings, and to cease to view their exploitation as natural and inevitable. As English philosopher Patrick Corbett said, “...we require now to extend the great principles of liberty, equality and fraternity over the lives of animals. Let animal slavery join human slavery in the graveyard of the past.”