There has been much debate over the years about whether animals experience emotions or not. Those who doubt the validity of animal emotions use the argument that emotions are not clearly defined even when considering humans. They also suggest there is a lack of scientific evidence and that much of the supportive evidence is anecdotal. On the other hand, those who support the notion of animal emotion have countered that since humans share universal emotive expressions, it is conceivable that animals do too. Furthermore, animals do not have to have particularly advanced cognitive abilities to experience emotions.
In addition, there would seem to be a growing body of evidence to suggest that animals can experience emotions. For instance, some animals do appear to express emotions through specific methods of communication (e.g. facial expressions, body posture, or sexuality). It may simply be that animals don't experience emotions on the same level as humans. For instance, they could conceivably feel anger, sadness, happiness - but they are unlikely to experience emotions associated with more complex human constructs.
The physiological feeling of emotions involves an increase in blood supply to different organs in the body such as the brain, muscles, heart and lungs, and the decreasing effect of blood supply to the intestines and outer parts of the body such as the skin. Emotions can therefore be revealed by the effects created from these variations of blood supply in our body.
Humans, for example, may experience the sense of sweating when nervous, blushing when embarrassed, increasing heartbeat when frightened, the face becoming pale when fatigued, and so forth. Animals, such as cats, may show emotional signs through hissing or spitting when they are unhappy, angry, frightened or defensive. Dogs seem to have some similar brain structures and hormones to those that produce emotions in humans. For instance, like humans, dogs produce oxytocin, which is associated with sexual behaviour, bonding, and maternal behaviour. For these reasons, in humans, oxytocin is sometimes referred to as the 'love hormone'.
Actions can also be a way of expressing emotions. For example, a horse may stop eating if it is feeling anxious, or a dog might not want to play if it is feeling weak or ill.
Primates such as the great apes seem to have developed a sense of “empathy” for others of their kind. For example, mothers appear to create strong bonds with their young and if their infant has died, these mothers have been seen to carrying the dead body for a few days, expressing sadness for their dead offspring.
Great apes may also manifest happiness or sadness in their facial expressions, displaying bared teeth if they have experienced frustration or loss, and a playful face if they are content.
Other displays of emotion have been observed when primates make contact with other members of their group, leading to actions such as grooming or embracing. These behaviours appear to be representations of consolation.
Cats have are known to demonstrate signs of anger by movements of their tail. They have been seen to thump their tails harder and stronger when annoyed or angry, compared to how they wriggle the tail when in a more content and satisfied state. Large cats such as lions growl loudly if annoyed or scared.
Moreover, the social behaviour of some fish has been observed to alter when they have been shifted from their natural environment to another. Those affected by this change might change their feeding patterns or prefer to be alone.
Seligman et al studied depression in dogs at the University of Pennsylvania. He used a model of 'learned helplessness' that has been related to humans. Learned helplessness is the term used to describe a mental condition in animals and humans where they have learned to give up trying, and instead behave in a “helpless” way. This state of helplessness may be arrived at in several ways. For example, in the past, no matter what their action, it did not change their situation - they kept failing, or they perceive that they do not have control over their situation.
A dog may whine and cry for food, but not be fed. If the dog is then given food randomly and the whining is ignored, it will learn that no matter what it does it will only be fed when its owner decides to feed it. As such, it becomes helpless to change the situation, and will stop whining when it is hungry even after being presented with food following whining. Similarly, if a child finds that no matter what they do, they cannot please their parents, they may learn that they cannot change their situation and they stop trying to please their parents. Again, learned helplessness can develop and they may stop trying to please their parents even by repeating behaviours which do actually please them.
Seligman et al separated dogs into three groups - a control group which would receive no intervention, and two experimental groups, A and B.
In a “shock condition” part of the experiment, the dogs in groups A and B were administered electric shocks. Group A had control over when they received an electric shock. Group B had no control. The control group were not shocked at all. The dogs were given curare, a paralysing drug, which interfered with their normal escape behaviour.
After the shock condition, the dogs were placed into a box where they could escape the shock by jumping over a partition. It was found that the dogs in the control group and those in group A would jump over the partition to escape the shock, whilst dogs in Group B would just passively take the shock. These dogs appeared to have learned that they would get the shock no matter what they did - they could not avoid it. This learned helplessness can then generalise to other situations. For instance, if the dog is placed in a tank of water it would most likely drown rather than attempt to swim to safety. Similar research has also been carried out on other species from fish to cats and rhesus macaques.
So, do animals get depressed? In humans, depression is diagnosed by looking at symptoms such as: loss of pleasure, suicidal thoughts, anxiety, negative affect, hopelessness, sleeplessness, and excessive sleeping. With animals, they are not able to communicate these thoughts and feelings, so we cannot really say whether they are depressed or not. But we can measure some aspects of depression in animals. Anhedonia, for example, is a loss of interest or reduced interest in pleasurable activities. Researchers can measure how much animals interact with other animals in their group, and if there are changes in their daytime activities and sleep patterns. We can also examine how quickly an animal gives up when exposed to a stressful situation. For example, in a home with two dogs, let's say one dog goes to the food bowl and the other dog growls at it, and this is followed by a fight over the food. In this instance, the researcher can measure how quickly the dog gives up the fight for the food.
In studies of non-human primates, trained observers have been able to ascertain whether a monkey looks depressed since they have emotional behaviours and facial expressions that are similar to humans. Careful observations of their facial expression and their gaze can indicate if an animal is experiencing sadness. One difficulty when studying animals in this way where they are in an artificial laboratory setting is that they are being raised in fairly impoverished conditions compared to their natural habitat. This can cause changes in their behaviour which mimic depressive symptoms. There is not much research which has reviewed depression in animals in the wild compared to laboratory settings. An animal that is depressed in the wild is possibly impairing its chances of survival. If we go back to the dog and the food fight, in the wild, if an animal quickly gives in, this behaviour may reduce its access to food or it could be more easily preyed on, reducing its chances of survival.
In captivity, some animals may appear to show depression. Veterinarians do give anti-depressants to animals, in particular dogs. Dogs may suffer from being separated from their owner with whom they have forged a strong bond, and so can develop abnormal behaviours such as scratching themselves until they bleed, or constant barking. It is thought that these forms of behaviour are canine versions of mental illness. Human anti-depressants and treatments do appear to work on dogs, but more research is also required on this. Medication should only ever be given to dogs under the instruction of a veterinarian.
Stress occurs as the result of our 'fight-or-flight' response. Stress can be very useful. If you were about to be attacked by a predator, your stress response prepares your body to fight or run (take flight). Problems can occur in humans when we become stressed inappropriately and do not know what to do with that stress. For example, a business executive may have a hard and demanding job. They may become angry and annoyed frequently. Their body prepares to respond to that stress by becoming physiologically aroused, but in the business environment having a fight with someone who annoys you is not beneficial, nor is running away, and so the person is not necessarily able to reduce their body’s arousal response to the stress.
The body responds to stress with an increased heart rate, increased blood pressure, increased blood flow to major muscles, and so on. When this happens, if a person is unable to release their stress, it can cause damage to the person’s body in the long term. Chronic stress can cause increased risk of heart disease, reduced immune function, ulcers and decreased sex drive, among many other problems. It can affect our sleep patterns and increase our blood pressure. It can also affect our motivation.
Cortisol is the stress hormone in our bodies. It has been found to be increased in people who are suffering from depression. It also increases as we age, making it harder for us to control our own stress.
Stress can also occur in animals. If an animal is moderately stressed, it is usually more alert than when it is not stressed - which is obviously a good thing from a survival perspective if they are at risk from predators or other life threatening events, or they are exploring a novel and unfamiliar environment.
An example of stress is highlighted in yabbies, a type of freshwater crayfish, which are under great amount of stress during their moulting period. Moulting contributes to an increase in susceptibility to injury, disease and predation before its new exoskeleton hardens. Although yabbies are able to tolerate a broad range of temperatures, being a cold-blooded species they are unable to control their body heat. The hormone responsible for inducing moult is activated at higher temperatures which helps to reduce the stress on the organism after it has shed is tough outer shell.
Yerkes and Dodson developed a model of stress to illustrate the relationship between arousal and performance. Performance increases as cognitive arousal increases, BUT only to a certain point. If stress increases too much, efficiency and performance will decline, so the animal's response to a new situation may be reduced which again could affect their survival chances.
Sapolsky has studied baboons in their natural environment in the Serengeti, Africa. He collected blood samples from male baboons and looked at their rank, social affiliations and personality. He found that three factors affected the cortisol levels of the baboons – rank, perspective and friendships. Only males were studied, as often the females were pregnant during the studies. He found that those baboons that cultivated friendships and played with infants were more able to determine whether a situation was a real threat and whether they were able to win or lose, and that these baboons also had lower levels of cortisol.
Sapolsky also studied rats and found that the early experiences of the rats had strong and lasting effects on their behaviour. He found that when rats were placed in stressful situations at a young age, such as through humans handling them, they adapted to the stress and were able to cope better to stress and that their ability to cope improved in accordance with the amount of stressful situations they experienced. So, basically, an animal will cope better with stressful situations if they learn to cope with stress well, and frequently, from an early age.
Eating Disorders in Animals
Animals in the wild seem to be free from eating disorders. Their bodies respond to seasonal and reproductive cycles. However, domestic animals and animals in captivity can be prone to eating disorders.
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