Cambridge Declaration on Consciousness

On 7 July 2012, at the close of the Francis Crick Memorial Conference on Consciousness in Human and Non-Human Animals at Churchill College, Cambridge, a small group of neuroscientists signed a one-page public statement. The Cambridge Declaration on Consciousness, authored by Philip Low and signed by Jaak Panksepp, Diana Reiss, David Edelman, Bruno Van Swinderen, Christof Koch and others, asserted that the weight of neurological evidence no longer supported the claim that consciousness is peculiar to humans. It was read aloud in the presence of Stephen Hawking and witnessed by the conference participants (Low et al., 2012).

The Declaration is short — roughly 500 words. Its conclusion is terser still: “the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”

The Francis Crick Memorial Conference

The conference was convened in memory of Francis Crick, whose late-career turn to the neuroscience of consciousness — with Christof Koch — helped legitimise the topic inside mainstream biology. The 2012 meeting brought together researchers working on anaesthesia, avian cognition, cetacean mirror self-recognition, insect learning, and the neural correlates of consciousness (NCCs) in humans (fcmconference.org). The Declaration was the meeting’s summative gesture, drafted by Low with input from the other signatories during the conference itself.

It is important to be precise about what the Declaration is and is not. It is a consensus statement by a group of attending neuroscientists, not a peer-reviewed paper, not an act of a learned society, and not a formal vote by any scientific body. It carries weight because of who signed and because the underlying evidence it points to is strong — not because the document itself is a primary study.

What the Declaration actually claims

Three scientific claims are embedded in the text.

The neocortex is not required for affective experience. Much twentieth-century neuroscience assumed that the mammalian neocortex was the seat of conscious feeling. The Declaration points out that sub-cortical structures — the periaqueductal grey, limbic circuits, and homologous networks — generate emotional states in mammals, and that lesion and stimulation studies show affective behaviour persists when neocortex is removed. Panksepp’s decades of work on basic emotion systems in mammals was central to this line (Low et al., 2012).

Birds display neural and behavioural parallels to mammalian consciousness. Avian brains lack a layered neocortex but possess a pallium with dense, functionally analogous circuitry. Behavioural evidence — corvid tool use, magpie mirror self-recognition, parrot referential communication — combined with neurophysiological homology, warrants ascribing conscious states to at least some birds.

Consciousness-supporting substrates extend beyond vertebrates. The Declaration singles out octopuses, whose distributed nervous systems show learning, problem-solving, and arousal-state dynamics comparable to those used to infer consciousness in vertebrates. This was the Declaration’s most provocative move: it broke the vertebrate containment that had quietly bounded most earlier consensus statements.

Signatories and scope

The list of signatories is small by the standards of later declarations — roughly a dozen core names including Low, Panksepp, Reiss, Edelman, Van Swinderen and Koch. Critics noted at the time that the Declaration was not circulated for broad scientific endorsement before release, and that its signatories, while distinguished, did not constitute a representative sample of the neuroscience community. Supporters countered that the document was never intended as a referendum; it was an expert consensus at a specific meeting, held in public.

Reception

Contemporaneous coverage in Wired, The Atlantic, New Scientist, and Discover framed the Declaration as a watershed: a long-overdue public statement of what many researchers had privately accepted for years (Grimm, 2012). Animal-welfare organisations quoted it widely. Within academic neuroscience the reception was more mixed — some researchers welcomed the statement; others objected that “substrates that generate consciousness” is a vaguer criterion than the document’s rhetorical confidence implies, and that the hard problem of consciousness is not dispatched by pointing to neural homology (Boly et al., 2013).

The Declaration’s lasting effect was cultural more than methodological. It made it professionally respectable to publish and to teach the claim that non-human animals are conscious, without hedging each sentence. It did not resolve the scientific questions it pointed at; it legitimised them as questions worth resolving.

From 2012 to 2024: the New York Declaration

In the twelve years after Cambridge, the empirical picture broadened. A UK-commissioned review led by Jonathan Birch (Birch et al., 2021) catalogued evidence for sentience in cephalopod molluscs and decapod crustaceans, and directly informed the UK Animal Welfare (Sentience) Act 2022, which recognised both taxonomic groups as sentient. Work on fish nociception, insect learning, and the dimensions of consciousness (intensity, integration, self-modelling) matured into a recognisable sub-field.

On 19 April 2024, a second consensus statement — the New York Declaration on Animal Consciousness — was issued at an NYU symposium and signed by nearly 40 researchers including Birch, Kristin Andrews, Jeff Sebo, Anil Seth, Nicola Clayton, and Lars Chittka, with the signatory list growing rapidly online (Andrews et al., 2024). The New York text extends the Cambridge claim in two ways. First, it asserts there is “strong scientific support” for attributing conscious experience to all vertebrates — explicitly including reptiles, amphibians and fishes — and “at least a realistic possibility” of conscious experience in many invertebrates, naming cephalopods, decapod crustaceans and insects. Second, and more consequentially, it treats that realistic possibility as an action-guiding fact: “it is irresponsible to ignore that possibility in decisions affecting those animals. We should consider welfare risks and use the evidence to inform our responses to these risks” (Andrews et al., 2024).

The two declarations sit in clear lineage. Cambridge told the scientific community what it had come to believe; New York told policymakers and funders what to do about it.

Implications for animal ethics and policy

The Declaration does not by itself answer an ethical question. That sentient beings have the neural substrates of consciousness does not entail that it is wrong to harm them — one still needs a moral premise linking sentience to consideration. But the empirical premise is what twentieth-century defences of animal use most often contested. Once the premise is conceded by mainstream neuroscience, the ethical argument simplifies (see ethics).

Three concrete downstream effects are visible.

Law. The UK Animal Welfare (Sentience) Act 2022, EU Directive 2010/63 on research animals, New Zealand’s 2015 amendment to the Animal Welfare Act, and several Australian state laws now recognise sentience explicitly. Cambridge and its successor are routinely cited in explanatory memoranda.

Research ethics. Institutional Animal Care and Use Committees have progressively extended protocols to cephalopods and decapods. Fish-welfare research funding has expanded in parallel.

Industrial practice. Large retailers and fast-food chains now commit, at least rhetorically, to cage-free and slower-growth standards for hens and broilers — reforms that presuppose the animals have welfare interests worth protecting. The reforms do not end the underlying use, but they accept the premise the Declaration stated plainly.

How to cite it honestly

The Declaration should be cited as Low et al., 2012, with the full context — a conference statement at the Francis Crick Memorial Conference, not a peer-reviewed consensus paper. The 2024 New York Declaration is its successor, not its replacement; both documents remain active touchstones for the claim that the sentience premise of animal ethics now rests on mainstream science, not on philosophical argument alone.