Since the 1990s, evidence supporting animal sentience has increased tenfold, demonstrating that animals possess the capacity for subjective experiences like pleasure and pain—states previously believed beyond their reach. This surge in evidence has amplified the animal rights movement, spotlighting the injustices prevalent in animal agriculture, research, testing, and challenging normalized societal views of animals.
A pivotal moment in this revolution was the establishment of Animal Sentience in 2015. This academic journal became the first to exclusively study the capacity of nonhuman animals to feel and think. By integrating ethics, neuroscience, animal behavior, and welfare science, Animal Sentience has provided a centralized, peer-reviewed platform for interdisciplinary research, marking formal recognition of animal sentience as a legitimate scientific field.
This milestone followed the Cambridge Declaration on Consciousness (2012), which affirmed that many nonhuman animals possess neurological substrates for consciousness.
By legitimizing research on subjective experiences in animals, Animal Sentience challenged behaviorist paradigms that had dominated much of the 20th century.
The journal’s influence extends to policy, with its research supporting legal protections for species like cephalopods and decapods in the EU and UK. The incorporation of animal sentience into UK law through the Animal Welfare (Sentience) Act 2022 demonstrates growing societal acknowledgment of animals’ capacity for suffering, supporting calls to end practices like factory farming and animal testing.
While these legal protections have helped improve animal welfare and awareness of animal rights, there is still much work to be done to implement the findings of the animal sentience revolution into industry and society.
Moreover, Animal Sentience has strengthened ethical arguments against practices like factory farming and animal research by highlighting evidence of sentience across diverse taxa.
In essence, Animal Sentience has played a critical role in advancing scientific understanding, fostered interdisciplinary collaboration, influenced policy changes, and shifted societal attitudes toward recognizing animals as sentient beings deserving moral consideration.
Animal Sentience helped pave the way for future landmarks in the animal rights movement, such as the New York Declaration on Animal Consciousness (2024) and the Animal Sentient Precautionary Principle (ASENT) Project (2019-2024).
The New York Declaration challenges paradigms in ethics, neuroscience, and societal norms. It explicitly rejects the assumption that consciousness requires human-like brain structures and the idea of human exceptionalism in understanding animal consciousness.
As the Declaration states, “The architecture for consciousness in other animals may look completely different than in humans… It is irresponsible to ignore [this] in decisions affecting animals.”
By challenging anthropocentric biases and recognizing consciousness as a trait shared across diverse species with varying neural architectures, the New York Declaration provides a framework for integrating scientific findings into ethical decision-making, urging society to reevaluate its treatment of animals in agriculture, research, and other industries.
The declaration marks a pivotal moment in the science of animal minds by combining empirical evidence with moral responsibility, pushing for systemic changes in how humans interact with nonhuman animals.
It also emphasizes that absolute certainty about consciousness is not required to take ethical precautions, advocating instead for a precautionary principle in decision-making.
If there is even a realistic possibility that an animal can suffer or experience harm, policymakers should consider this when crafting laws and regulations. By assuming consciousness, we can create better animal welfare practices and ensure that no sentient beings are harmed.
If consciousness isn’t human-specific, speciesist hierarchies (e.g., prioritizing mammals over fish) become untenable. This realization highlights the fact that speciesism is a construct, and thus our understanding of speciesism is shaped by human perception and cultural systems, rather than being an objective, universally fixed reality.
Building on this foundation, the ASENT Project (2019-2024) has challenged binary classifications of sentience by proposing a multidimensional framework that considers valence (pleasure/pain), arousal (intensity), self-awareness, and social awareness across species.
By rejecting binary thinking, ASENT helps us understand that sentience isn’t one-size-fits-all. It’s not just about whether an animal can feel pain – it’s also about how deeply they experience the world around them. Are they self-aware? Can they form social bonds? And what’s the emotional intensity behind their experiences?
ASENT’s spectrum model widens our definition of sentience, allowing for what is classically considered partial evidence (e.g., chickens showing empathy) to warrant ethical safeguards.
The ASENT framework emphasizes taking preventative action when there is a threat of harm by stating that “Uncertainty about sentience does not justify inaction.”
These milestones highlight a critical point: sentience should not be a prerequisite for welfare.
Because our understanding of sentience is largely based on the human experience, there is a high likelihood that animal consciousness differs from our own in ways we may not fully comprehend, which is further complicated by humans’ incomplete understanding of our own species’ consciousness.
Animals that have not been proven sentient are labeled as non-sentient until proven otherwise, leading to the risk of inflicting harm on sentient beings.
As science evolves, more species are recognized as sentient, underscoring the need to assume sentience until proven otherwise and to grant welfare to all species based on their intrinsic value. The intrinsic value of animals refers to the idea that animals have inherent worth, independent of their usefulness or value to humans, meaning their lives are valuable in and of themselves.
The evolving landscape of animal sentience science is highlighted by groundbreaking research from 2023 which found that bees have emotions, can plan and imagine, and recognize themselves as unique entities, when it was once thought that all insects, including bees, were mere automatons.
Additionally, breakthroughs in neuroscience and ethology show that animals previously thought incapable of feeling pain—such as crustaceans and cephalopods—are indeed sentient. This evidence dismantles arguments justifying their use in food and research industries and further supports the argument to assume consciousness until proven otherwise.
The utilitarian classifications of living organisms used in the speciesist hierarchy lays the foundation for humans to justify inflicting harm on each other based on perceived traits of moral or performance superiority.
Speciesism places Homo sapiens at the top of a hierarchy that is used to justify sacrificing other animals. Harmful practices and ideas about animals that are deprioritized in the speciesist hierarchy are used to rationalize colonial practices and violence towards groups of people.
Speciesism allows certain animals to be exploited and treated as commodities to accommodate human needs and desires, while other animals with the same capacity to experience emotion can be considered family.
In 1999, the Treaty of Amsterdam went into force, granting animals official recognition as sentient beings in the EU, which demonstrates widespread acceptance of animal sentience. However, the practices used in animal agriculture and animal testing disregard the fact that animals such as cows, pigs, chickens, and rats are capable of experiencing a significant range of emotions, including fear, stress, pain, social bonds, joy, empathy and affection. This juxtaposition highlights a significant level of cognitive dissonance associated with the production and consumption of animal products as well as products tested on animals.
Despite our knowledge of their ability to experience subjective states, chickens, pigs, and cows are viewed as commodities in society, raised simply for consumption without deliberation on their wellbeing.
In industrialized agriculture, these animals are confined in cramped, unsanitary conditions to maximize production, leading to suffering and disease. Calves are separated from their mothers within a few hours of birth and male piglets are castrated without anesthesia. However, the normalization of speciesism in society enables people to turn a blind eye to the 10 billion animals that are killed on factory farms in the USA annually and their suffering.
Humans must challenge our idea of superiority in the animal kingdom, recognizing that we are animals too. It is unjust to engage with practices such as laboratory testing, animal agriculture, and the destruction of natural habitats due to the distress and pain these practices inflict on innocent, sentient beings in addition to the harm they inflict on the Earth.
The U.S. animal agriculture system inflicts unfathomable suffering on sentient beings while pushing Earth’s systems toward irreversible tipping points. As animal agriculture severely threatens several planetary boundaries, including climate change (release of CO2 and other greenhouse gasses), biogeochemical flows (nitrogen and phosphorus), land-system change, freshwater use, and biosphere integrity (the loss of biodiversity).
Vegan ethics align with the scientific consensus on animal consciousness and the urgency of staying within planetary boundaries.
The convergence of animal sentience science, climate urgency, and planetary boundary breaches creates a compelling ethical and ecological case for transitioning to veganism in the U.S. Here’s how these elements interconnect:
- Animal Sentience Demands Moral Consideration:
- The ASENT framework and New York Declaration dismantle human exceptionalism by proving sentience is widespread. Mammals, birds, and many invertebrates (e.g., octopuses, crabs) exhibit pain, fear, and pleasure. ASENT’s spectrum model rejects binary distinctions, meaning even partial evidence (e.g., chickens showing empathy) warrants ethical safeguards. Monthly in the U.S., 32.8 million cattle and 11.5 million pigs are slaughtered, despite 94% of Americans believing farmed animals deserve freedom from abuse, demonstrating moral consideration of animal wellbeing with a significant gap in action.
- The Myth of “Humane” Farming:
- Factory farm conditions are characterized by overcrowding, with chickens packed into sheds with <1 sq ft/bird and pigs confined to gestation crates too narrow to turn around. Routine cruelty is evident, with Foster Farms (certified “humane”) violating federal welfare laws 18 times (2021–2022), including drowning conscious chickens and suffocating live birds. Genetic manipulation and rapid growth induced by high nutrient intake causes chickens to grow faster than natural rates, resulting in skeletal collapse and severe lameness.
- “Humane Slaughter” is an oxymoron, as the Humane Slaughter Act excludes 9.7 billion chickens and turkeys slaughtered annually, allowing live-shackling and ineffective stunning. Even for covered species, 16% of cows are ineffectively stunned during slaughter due to rushed bolt-gun procedures resulting in repetitive stunning or slaughter while conscious. Additionally, there are countless allegations of abuse, violations, and deceptive practices against farms that hold humane farming certifications. For example, investigations into Plainville Farms, a Global Animal Partnership certified facility, revealed workers kicking, beating, and throwing turkeys, with sick and injured birds left untreated. Animal Welfare Certified Farms have been found guilty of animal abuse, including workers kicking birds and forcing screaming pigs into gas chambers.
- Animal Agriculture and Planetary Boundaries:
- Animal agriculture significantly contributes to climate change, accounting for 14.5% of global GHG emissions, with U.S. beef production emitting 20x more CO₂ per calorie than plants. It also strains freshwater resources, requiring 1,800 gallons of water for 1 lb of beef versus 39 gallons for 1 lb of vegetables. Furthermore, it drives ecological collapse through deforestation, as 80% of Amazon deforestation is linked to cattle ranching and soy (for feed), and biodiversity loss, with livestock occupying 77% of agricultural land but providing only 18% of calories.
- Ethical Imperatives and Solutions:
- The New York Declaration urges avoiding harm where consciousness is a “realistic possibility.” Given ASENT’s evidence, this includes all vertebrates and most invertebrates used in agriculture. The precautionary principle dictates that uncertainty about sentience does not justify inaction. Veganism offers a solution, reducing suffering by eliminating demand for animal products, which directly reduces slaughter rates, and mitigates climate change by shifting to plant-based diets, potentially cutting agricultural emissions by 49% and land use by 76%.
Rejecting speciesism is not only a moral choice but also crucial for the planet’s survival.
Developments in animal sentience science confirm that animals experience subjective states such as pain, fear, empathy, and pleasure, making their exploitation morally indefensible.
Sentience-based ethics challenge speciesism by dismantling the hierarchy that places human interests above those of non-human animals.
Evidence of animal cognition, such as playful behaviors in bees and problem-solving in octopuses, underscores the ability of science to evolve overtime and the need to assume consciousness in order to ensure that no sentient beings are harmed.
These scientific advancements strengthen the moral argument for veganism by revealing the inherent suffering and exploitation in animal agriculture, advocating for systemic change in research, societal norms, and practices. Moreover, they challenge anthropocentrism by showing that consciousness is not uniquely human nor reliant on familiar neural structures. We must recognize that sentience is a spectrum with diverse evolutionary origins, and revise animal welfare laws, research ethics, food systems, and our relationship with nonhuman life.
