We’ve all heard them and used them – the common references to farmed animals that appeal to the worst part of human nature: ‘pearls before swine’, ‘what a pig’, ‘like lambs to the slaughter’, ‘bird brain’. These phrases represent our species’ view of farmed animals as not particularly bright, uncaring about their treatment or fate, and generally bland and monolithic in their identities. My team of researchers asked: ‘What is there to really know about them?’ Our answer: plenty.

I’ve had the privilege of being the lead scientist for the Someone Project, a joint venture of two US nonprofit organisations, the Kimmela Center for Animal Advocacy, and Farm Sanctuary. The Someone Project is an exploration of our scientific knowledge of the minds of farmed animals. My co-authors and I have explored the peer-reviewed literature on intelligence, personality, emotions and social complexity in pigs, chickens, cows and sheep, and the journey ‘inward’ into the minds of these animals has been nothing short of revelatory.

While most people accept that farmed animals possess simple emotions such as fear, they are less open to the idea that the animals’ emotions can be familiar and complex. One example is cognitive judgment bias, also known as optimism and pessimism. We all know the feeling of being able to take on the world when bolstered by good experiences and praise. And, unfortunately, we also know what it feels like to give up when we are pummelled by bad experiences. Cognitive bias is a deviation in judgment as a result of emotional experiences. How we interpret ambiguous stimuli or situations depends upon whether we are depressed or anxious, or feeling on top of the world. Pigs, chickens, sheep and cows feel it too. Just treat cows, sheep or chickens roughly through exposure to loud noise or the presence of a predator, or any other uncontrollable negative condition, and assess how they perform on a typical discrimination task differentiating between two stimuli to get a reward. Just like you, all that stress biases their brains and ability to do well.

In one study, sheep had to learn to discriminate between two buckets marked with different visual patterns (horizontal versus vertical stripes) and respond by walking over to either end of the room to the bucket associated with food. Sheep who experienced prior aversive events were compared with an unexposed group. When confronted with this simple task, the stressed-out sheep were more reluctant to approach the buckets and made more errors than their unexposed counterparts. After a tough life, they view the world through the opposite of rose-coloured glasses. Sound familiar?

If farmed animals are so vulnerable to bad treatment, how can we maintain the illusion that having one’s tails, ears and horns cut off makes no difference to them? The fact is that several scientific studies show sheep in despair, with physiological signs of stress and depression when subject to unpredictable and uncontrollable conditions such as the sudden appearance of a new object while they are eating. They are experiencing the well-known psychological phenomenon of learned helplessness, in which learning that one cannot control one’s environment or life leads to depression and lack of motivation to even try. Learned helplessness is seen in sheep, in other farmed animals, in many animals in zoos and marine parks, in lab animals, and, yes, in humans who experience continued hard knocks throughout life, especially as children.

One of the most insidious misconceptions about farmed animals (indeed almost all animals aside from human ones) is that they do not care about their young, who do not need a mother for normal development. This mythology of emotional detachment has become the lore for chickens, cows, turkeys and other farmed animals. But what is the evidence for this convenient fabrication? At first blush, it is irrational to think that any mammal or even vertebrate would be indifferent to their offspring. If that were the case, none of us would be here now.

Instead, there is ample evidence that farmed animals care very much about being able to raise their offspring. Several studies show that calves must be brought up by their mothers to be socially well-adjusted. Young calves allowed to stay with their mothers grow up more socially confident with other cows. Conversely, cows prevented from being raised by their mothers show more fearful responses to novel situations and unfamiliar cows. Dairy calves raised in more complex social groups in general tend to have increased coping abilities and higher capacities for dealing with change. The same effects are seen for piglets and lambs.

For starters, mothers need to be able to send out their offspring into the world well-prepared, and that means weaning them on a natural timescale. During weaning in sheep, lambs gradually become less dependent on mother’s milk and more involved in foraging for food on their own as mother stands watch. But no factory-farmed animals are afforded this basic necessity. Sheep naturally wean at six months, but on factory farms mother and offspring are separated at between one and two months. Cows naturally wean between six and nine months, but dairy cows are separated within 24 hours. Pigs naturally wean at about three months, but mother and piglets are typically separated within 17-20 days on factory farms. And the situation for chickens is just as severe. If left on her own, a hen will look after her chicks for between six and eight weeks. Under factory-farming conditions, layer hens never get to see their offspring, and chicks raised for meat are killed at six weeks of age, still peeping the sound of a baby chick even though their bodies have been genetically manipulated to balloon to the size of an adult.

What are the psychological consequences of these extreme practices? Just what you would expect – mother cows running after their abducted newborns, bellowing and restlessly searching when they are gone. When ewes (mother sheep) are separated from their lambs before weaning, they let out high-pitched vocalisations, pace, and even urinate. And studies suggest that early separation from the mother has negative psychological impacts on lambs throughout progressive phases of their social development. Lambs artificially weaned at a very early age show less vocalising and movement, are generally more socially withdrawn, and exhibit abnormal, repetitive oral behaviours.

She spent all her time trying to protect the chicks, literally taking them under her wings when humans were around

Maternal bonding and concern are not restricted to mammals. When mother hens receive a mildly aversive puff of blown air, they do not respond particularly strongly. But when they see someone ‘air puff’ their chicks, they show signs of distress, including clucking, increased heart rate and alert posture.

Meet uber-mother June. June came from a cockfighting operation in New York City (hens themselves are not made to fight but are kept in confined conditions as breeders) where she spent all her time trying to protect her chicks and the chicks of other hens from the abuses of the situation, literally taking them under her wings when humans were around. Fortunately for June, she was rescued and went to Farm Sanctuary where she need not fear humans. But she still kept her chicks close by – even when they were too big to hide under her wing – and fought off anyone who came near them. She never forgot the abuses she suffered, even after many years in the sanctuary.

The inner lives of farmed animals cannot be characterised entirely on a species level. Instead, they are unique individuals with personality to spare. Those personalities map familiarly onto the same characteristics that comprise human personalities. The five dimensions of human personality structure are extraversion, agreeableness, conscientiousness, neuroticism and openness to experience. Most of us fall somewhere along the spectrum for each category. For instance, in the first category, each of us is either extremely extraverted, extremely introverted or somewhere in between.

Research shows that, like humans, individual pigs fall along the dimensions of agreeableness, openness to new experiences, and extraversion. For instance, in a competitive feeding situation, the pig who is the most aggressive tends to keep that reputation throughout time. Cows similarly fall along a spectrum on dimensions of extraversion and also neuroticism. Sheep have personality traits characterised in the literature as ‘shyness/boldness’ and ‘gregariousness’, comparable to openness to experience and extraversion in humans. Finally, individual chickens (and turkeys) also vary along dimensions of personality, including boldness/shyness, activity/exploration (in humans, openness to experience), and vigilance (similar to neuroticism in us). Personality shapes maternal style in chickens and hens through the dimension of vigilance; the most extreme on one end tend to be the ‘helicopter moms’ of the barnyard.

As complex and familiar as these personality traits are, they have not been studied nearly as much as human personality, and are clearly only the tip of the iceberg when it comes to understanding who farmed animals are. Up until today, the scientific community has been slow to acknowledge personalities in other animals, even our closest feline and canine companions. The fact that, amid this juggernaut of denial and homogenisation on the factory farm, the personalities of cows, pigs and chickens still shine through is testament to the strength and resilience of their identities.

Not only are farmed animals individuals, they recognise the individuality of others. We humans are into faces. We like ones that are pleasant and convey positive emotions. We love smiles. As primates, we are especially attuned to facial expression. And we use faces for the recognition of individuals (including our nonhuman companions). It might be difficult to recognise a friend from a photo of a leg or a hand, or your dog from a photo of her tummy, but you would never fail to recognise their faces. We post pictures of the faces of celebrities and people in the news – not their elbows.

This focus on faces and the information they confer goes beyond the fact that faces contain mouths, and mouths vocalise. That’s because the facial expression and the identity of the person vocalising are often more important than what is actually being said, content-wise. Moreover, faces contain eyes, and the gaze direction tells me where you’re looking and, therefore, what you know or if you are paying attention to me. No child has escaped the question asked by teachers and parents: ‘Are you paying attention to me?’ So identity, emotion and attention are written all over our faces.

Faces are complex configurations of various components, and face recognition is, similarly, a complicated mental task. For all of these reasons, we are not particularly surprised by evidence for facial recognition in dogs or chimpanzees. But what about farmed animals? Are they just faceless entities in a crowd or herd? The answer is no.

Pigs, like primates, dolphins and dogs, understand pointing as a reference to an object

It turns out that many farmed animals are attuned to faces of members of their own species, as well as those of other species. Sheep are the ‘face experts’. Well-controlled studies requiring sheep to discriminate pairs of photos of other sheep show that they are capable of remembering the faces of 50 different individuals for more than two years. And, like us, they strongly prefer certain expressions over others. As highly social mammals, sheep are sensitive to emotional expressions and are able to distinguish between and prefer photographs of sheep with a calm facial expression over sheep with a startled expression. And sheep are celebrity-watchers as well. Studies show that they can discriminate among photos of four different human celebrities even when the faces are presented to them in different spatial orientations. Altogether, sheep have extremely sophisticated face-recognition abilities on a par with humans and other primates.

Cows can recognise the faces of different cows, and even discriminate photos of cows of several different breeds from other non-cow species (dogs, sheep, horses and goats). Chickens, too, show notable abilities to recognise individuals in their own social group as well as keep track of the social dominance hierarchy (known as the pecking order). Hens can gain useful information about their own status in the dominance hierarchy before actually taking on a challenger by observing how that hen interacts with another hen she is familiar with. If the challenger can be chased off by the familiar hens who are lower than her in the hierarchy, then she is more likely to engage in some sparring with her. They are, apparently, wise enough to challenge only those chickens they know they stand a good chance against. In science, this kind of logical reasoning is called transitive inference, the ability to derive a relation between items that have not been explicitly compared before. Whether or not chickens accomplish this feat in exactly the same way that we do, these findings show that they are not just mindlessly spending their days pecking away at tidbits but are actually processing social relationships in pretty complex terms.

And several studies show that pigs are quite skillful at using head cues to discriminate between different attention states in humans. Like all of us, they prefer interaction with us when we are looking at them than when we are turned away. And it’s the same for other pigs. And pigs, like primates, dolphins and dogs, understand pointing as a reference to an object. They learn these social-cognitive skills at a young age.

In the past few years, scientific advances in our understanding of animal minds have led to major shifts in how we think about and treat other animals in zoos and aquariums, at least in the West. The general public is starting to realise that animals such as apes, elephants, dolphins and whales have complex inner and social lives, and that we need to treat them accordingly. For instance, there is a growing viewpoint that whales and dolphins should not be in concrete tanks performing for our entertainment and, accordingly, there are major efforts underway to call attention to and end this practice.

But despite this growing realisation for many animals held captive for our entertainment, traversing the path toward recognising the mental lives of farmed animals such as pigs, cows, chickens, sheep, goats and turkeys has been far more daunting. Although vegan and vegetarian food options are becoming more plentiful and more common, meat consumption, on a global scale, has increased in recent years, and it continues to be high on the list of coveted recreational and dining experiences for most people in the developed world.

In 2012, The Economist reported that, based on 2007 data from the UN Food and Agriculture Organization, meat consumption since 1961 has risen from about 48 to 88 pounds per person per year worldwide. The numbers of individual farmed animals slaughtered for meat annually around the world also showed a staggering increase from 1961 to 2014: we’ve gone from 6.6 billion to 62 billion chickens; from 376 million to 1.5 billion pigs; from 331 million to 545 million sheep; from 173 million to 300 million cows; from 142 million to 649 million turkeys; and from 103 million to 444 million goats. These statistics do not take into account eggs, dairy and seafood.

Why, despite all of the information, is the problem of meat-eating so intractable?

The increase has occurred despite growing scientific evidence for severe health hazards for humans who eat certain kinds of factory-farmed meat on a regular basis. Regularly eating red meat is tied to increased risk of diabetes, cardiovascular disease and certain cancers. At the same time, the evidence for better health and wellbeing associated with eating less meat is well-established.

And, from the point of view of animal suffering, there is extensive information available on social media, in films and in writing about the poor quality of life and violent end endured by factory-farmed animals. But, again, the practice continues. One must ask: why, despite all of the information, the problem of meat-eating seems to be so intractable?

Perhaps the answer can be found in the inner lives of members of our own species. We are masters at erecting psychological defences and justifying behaviour that we know is not ethical but feels good, such as pleasuring the palate. The main form that these defences, these mental pushbacks, take is a cultural mythology that promotes a view of farmed animals as devoid of feeling, awareness, intelligence and concern about their own quality of life. In the face of unimpeachable evidence for their suffering and our health risks, the last bastion of defence for human carnivores is to convince oneself that farmed animals do not care whether they live or die or how they live. We tell ourselves that their suffering isn’t the same as ours and that they don’t really care about life the way we do, so why should we care?

The inner lives of farmed animals depend upon who the farmed animal is, but also overlap into familiar territory within our own minds. Each species has its own nature, and each individual his or her own life. But the scientific literature on everyone from pigs to chickens points to one conclusion: farmed animals are someone, not something. They share many of the same mental and emotional characteristics that we recognise in ourselves and acknowledge in the animals closest to us – dogs and cats. To continue our self-indulgence, we resist the evidence and reinforce the status of farmed animals as objects, as commodities, as food. Their inner lives have become ‘the forbidden territory’ we dare not enter lest we deprive our palate and shatter our sense of ourselves.