Emotion

Scientists define animal emotions as ‘short-lived responses to stimuli, designed to guide animals towards rewards and away from danger’. In this sense, emotions serve as adaptive survival mechanisms with an array of neural, physiological and behavioural components in order to respond effectively to stimuli and situations. This theory is supported by Darwin’s evolutionary approach.

Mood

Where emotions are short-lived responses to stimuli, like a startle response to a predator, moods are instead considered longer-term ‘affective states’ unrelated to stimuli, like depression or excitement. Affective states can be negative like chronic fear, or positive like contentment, and are not caused by a single stimulus but are the result of an accumulation of experiences.

Cognitive bias testing measures how an individual’s emotional state has affected how they process information. Attention bias testing is an effective method, and sheep have been widely used to demonstrate this, especially for depression and anxiety. With humans, anxious people tend to spend more time worrying about threatening information than non-anxious people – the same is true for animals, who can also possess this frame of mind. Unfortunately, animals can’t tell us how they’re feeling – but we can confirm whether these animals are experiencing anxious states through attention bias testing. Accuracy of these tests have been evidenced by using environmental and pharmaceutical manipulations to induce anxiety, then measuring attention response rates towards threatening stimuli. For example: the time it takes for sheep to approach a food reward after a threatening stimulus (like a dog seen through a glass window) has been removed, and the time spent attentive to the potential threat. In this example, anxious sheep will spend more time being vigilant than the non-anxious Control sheep. This 2016 research is a good example; and this 2018 study shows how depression can also be identified.

Judgement bias testing is one of the most effective ways to assesses an animal’s state of mind. The underlying hypothesis is that an animal with a negative state will make negative judgements about ambiguous stimuli, or view the world in a negative light to be more general. The first published study on cognitive bias illustrated this in 2004; rats in unpredictable housing conditions were hypothesised to have negative affective states, contrary to other rats in stable control conditions. The experiment involved training rats to associate sounds with events. When presented with two cues in the form of a tone of particular frequency, both sets of rats were trained to perform a response which would either A) avoid a negative event, or B) illicit a positive event respectively. What about when the rats then heard an unenforced ambiguous tone, which was not associated with either event? Will the ‘sad’ rats categorise it as negative, while the ‘happy’ rats don’t? Yes, that’s exactly what happened: confirming the researchers’ hypothesis that rats with a negative cognitive bias will categorise the ambiguous tone as negative, and perform the response to avoid a negative event. This approach to measuring states has been widely used in lab and farm settings, using monkeys, rats, dogs, sheep, birds and humans – and results support the validity of the cognitive bias testing hypothesis.

Historically, brain size was viewed as a proxy for cognitive abilities, but today scientists dismiss this simplistic view and the topic remains in debate. Many animals have much bigger brains than humans – our brain weighs roughly 1350g, whereas an elephant brain is about 5kg, and a blue whale weighs in around 7kg: simple comparisons of brain size across species does not equate intelligence. Brain size relative to body mass is another avenue science has probed, but again with contradicting results. The human brain occupies 2% of our body mass, whereas the blue whale’s brain only occupies about 0.01% – this would be a good theory aligning with our expectations, except for the fact that the shrew and harvest mouse come up tops with a brain occupying between 4% – 10% of their total body mass. Back to the drawing board. The importance of certain parts of the brain in intelligence is still hotly debated – for example, the cerebral cortex especially the neocortex is considered responsible for higher cognition and so dubbed the ‘seat of consciousness’. Some believe it is necessary for animals to possess this structure to experience pain or emotion, whilst others consider lack of a neocortex to be rather flimsy grounds for denying pain in non-mammals, as evidence has pointed that emotions can derive from parts of the brain outside this. This is something supported by the 2012 Cambridge Declaration on Consciousness (a prominent international group of cognitive neuroscientists, neuropharmacologists, neurophysiologists, neuroanatomists and computational neuroscientists), which stated

‘the neural substrates for emotions do not appear to be confined to cortical structures’. The latest theory compares brain size – body mass again, but this time using ‘allometry’: in simple terms, evaluating characteristics across species and identifying species whose brains are larger or smaller than expected for their body size. Results for the main vertebrate groups largely align with the behavioural complexity observed in each species, so this is the theory most scientists are running with today, but of course it is a theory and not yet a fact. However, brain complexity and brain size can change independently of one another, and a brain can become more intelligent relative to its ancestral species whilst decreasing in size. Neural complexity in insects is among the most noteworthy displays in the animal kingdom, and the underlying component of the nervous system which deals with cognitive and social behaviour has changed in complexity for several insects including butterflies and bees, and according to some the latter can be compared to the folding of the mammalian cortical surface. The role brain size plays in determining intelligence is still under much investigation and there are many contradicting studies – E.G. this research on guppies in 2018 suggests brain size influences behavioural plasticity. Biological complexity and intelligence is evidenced across species, and the exact selection pressures remain in debate today.

Behavioural plasticity (adjusting behaviour in response to complex environmental conditions) has long been thought to indicate superior cognitive ability, mainly in terms of learning and adaptability – thus an inference for consciousness. Complex behaviours certainly require a greater degree of awareness, but in the words of Balcombe, ‘intelligence’ should be recognised as a suite of abilities specific to each species’ ecological challenges, not one single property. Fish are a good example. Because fish do not scream when impaled with a hook, and have no discernible facial expressions, we assume they do not feel pain – that they are simple stupid creatures, only capable of basic cognitive processes. Research has shown us we are wrong – that fish have the cognitive capacity to plan, learn, use tools, hold long-term memories; there is evidence of perspective taking, social cohesion, complex relationships, and individual recognition. Goldfish, viewed by many as the pinnacle of fish stupidity, are actually viewed very differently by scientists; contrary to popular belief, the urban myth that goldfish have 3 second memories has been disproved time and time again by research which has instead shown them to possess not only an impressive memory, but also problem-solving skills: E.G. in this 2003 research where goldfish learned to operate a lever for food and,

even more impressively, independently discriminate which 1hr time slot out of 24hrs was the correct time to do so! In 2012 a now famous experiment showed adult cleaner wrasses outperform chimpanzees, orangutans and capuchin monkeys! Two plates were presented to the animals – one was blue and one red. When the animals took the food from the blue plate, the red was taken away (so halving their meal), but when animals took food from the red plate first, the blue plate remained. It took the fish about 45 trials to figure this out – some of the primates never did, even after 100 trials. The experiment was based on decision making, which is important for the wrasses who are ‘cleaner fish’ and must choose to service visiting reef fish before resident reef fish in order to get both meals. This shows again intelligent behaviour depends on what challenges a species faces in the wild. If complex behaviours indicate sentience, then we should regard fish as we do our furry companions – a striking claim, hard to believe for most of us, yet a logical conclusion nonetheless. This reminds us that we often underestimate that which we do not understand and we, the human race, are but one of the millions of species on this planet – a mere pin-drop in an ocean of life.

Research results are consistent, and although it may never be possible to prove beyond a doubt that animals experience sentient emotions, many scientists believe we should err on the side of caution. Translating this science into real life changes however is a failing endeavour – E.G. the everyday act of boiling crustaceans like crabs and lobsters for dinner. From my own personal experience, every summer a trip to our holiday home in the West coast of Ireland would be accompanied by throwing in the lobster pots, hopefully catching one or two for tea. As a child I was distressed to see the lobsters boiled alive, and the high pitched whines and whistles that bubbled up relentlessly from under the lid ensured however yummy the tea was, it came sprinkled with a side of guilt. I was reassured calmly by my father that they didn’t feel anything, because placing them in the freezer for a few hours beforehand induces a state of hibernation – then when placed in the boiling water, it’s over before they know it. Reluctantly I accepted – as do millions of people across the globe today casting in their own lobster pots or ordering in restaurants. Now I know there is no clear evidence that freezing crustaceans to torpor induces anaesthesia rather than just paralysis, and freezing could be harmful in itself. The technique originates not from welfare scientists but chefs, in order to immobilise the lobsters who otherwise thrash wildly and scrape the sides of the pot in desperate attempts to escape. I’ve reflected greatly on why lobsters and crabs earn no sympathy; perhaps the misconception lies with size, and people deem these animals too small to feel pain or fear? This seems unlikely though as many other furrier animals are of similar size,

and closing the lid on either a budgie or a rat is likely to be met with outcries of animal cruelty. Perhaps it’s the way they look, then; does the scaly exterior remove it in our minds as an animal, replacing it instead as some strange, hard creature from an alien world? If they had fur, would that change anything? What if they communicated vocally; if lobsters sang like birds, or huffed like bears would we still boil them alive? Maybe our understanding is too limited, and as a rule only extends so far into the underwater world so opposite to our own, despite being two sides of the same coin. If growing evidence suggests lobsters can feel pain, should they not be slaughtered in a more humane way? Recent research has also shown crustaceans display the hallmarks of stress and anxiety like those we accept in sheep. Boiling lobsters alive has been illegal in New Zealand since 1999, and as of 2018 Switzerland too – but remains the norm in many other countries. The science is there, but change it seems is dependent upon social attitudes and norms. Perhaps lobsters are just too removed from us as humans, and too different from the other forms of life whose validity we are comfortable accepting. This need for a wiser compassion extends well beyond how we put food on our plates, but also to what we do for fun; the pets we keep, the places we visit, the clothes we wear and even the beauty treatments we buy: if you could see where those mink eyelashes came from, would you still want them on your face? Nobody’s perfect, but being kinder to animals is easy, it just requires asking the right questions: is this coat real fur? Are these lashes synthetic or mink? Where did my pet shop source my ________ from, and where did the breeder get the parents / grandparents?