Animals

Scientists say we are not the only conscious animals

By WhyStopHarmingAnimals.com

In 2012, at the Francis Crick Memorial Conference in Cambridge, a group of neuroscientists declared that the weight of evidence shows humans are not unique in possessing the neurological substrates of consciousness[1]. All mammals and all birds, they wrote, possess them as well[1].

Twelve years later, scientists went further. The New York Declaration on Animal Consciousness, published at NYU in 2024, says there is strong scientific support for conscious experience in mammals and birds[2], and at least a realistic possibility of it in all vertebrates, including fishes[2], and in many invertebrates. It adds a practical rule: when there is a realistic possibility of conscious experience in an animal, it is irresponsible to ignore that possibility in decisions that affect them[2].

Every animal farmed for food on a large scale, from cows and pigs to chickens and farmed fish, falls inside those lines[2].

What the declarations do and do not say

Both documents are statements by scientists summing up existing research. They are not new experiments, and they make no claim to know exactly what it is like to be a hen or a trout. The New York Declaration chooses its words carefully: "strong support" for mammals and birds[2], "realistic possibility" for other vertebrates[2].

That caution is the point. The declaration does not ask anyone to be certain before acting[2]. It says the possibility alone is enough to count[2]. For the animals we farm, the evidence is well past that bar.

The evidence behind the words

Across the species we eat, research keeps turning up minds.

Cows recognize their own calves by voice[3]. In playback experiments published in Animal Behaviour in 2016, mothers were more likely to look, turn or walk toward a recording of their own calf than toward an unfamiliar one[3], and calves did the same for their mothers[3]. Heifers who learned to solve a task showed bigger heart-rate and behavioral reactions at the moment of success than cows who got the same rewards for nothing[4], a sign that they register their own learning[4].

Pigs given five hours with a mirror learned what the reflection shows[5]: in a 2009 study, seven of eight used it to find a hidden bowl of food[5], while pigs without that experience searched behind the mirror[5].

Hens tell individual flock-mates apart[6], around 100 of them by classic estimates, and they react when their chicks are in trouble[7]. In a 2011 study, mothers whose chicks were exposed to a mild puff of air became more alert, preened less and showed a drop in eye temperature[7], a physiological sign of stress, although the hens themselves were untouched[7].

Fish show it too. Bluestreak cleaner wrasse try to scrape off a mark they can see only in a mirror[8], a result reported in PLOS Biology in 2019 and strengthened by a 2022 follow-up[8]. Rainbow trout have pain receptors like ours[9], and morphine reduces their pain-related behavior[10].

Several of these studies are small. The mirror work in pigs and fish used a handful of animals, and the calf-call and heifer studies are observational. They are also consistent with each other, and with the conclusions of two separate groups of scientists who reviewed the field.

What follows

If there is a realistic possibility that a fish can suffer[2], and strong evidence that a cow or a hen can[1][2], then the way these animals are treated has to be judged as the treatment of someone. Treating them as objects is a choice made in spite of the science, and it is a choice we do not need to make. Nobody has to eat animals to live, so the harm done to them is harm we could stop.