Where do emotions come from, and why do we have them?

How do you know when you're in a particular mood or emotional state? Do you look to your thoughts and reasons, or to your physiology?

For hundreds of years, people have known that physiology affects how we feel. In medieval times, people had a theory of the "Four Humours". Depending on how much of certain fluids you had in your body, people thought you could predict or explain certain moods. Blood was thought to cause changeable moods, black bile was thought to be responsible for melancholia, phlegm for sluggishness, and yellow bile was present in those with anxiety.

Whilst medieval theory didn't hold true, another biological theory emerged a few hundred years later - the idea of embodied emotion.

Charles Darwin, in his study of different species, noted that despite many animals lacking the high cognitive capacities of humans, animals experience the same six basic emotions as we do: happiness, sadness, fear, anger, surprise, and disgust. He argued that emotions are innate and distinct from cognition, and that they emerged due to their fitness value, because they enabled quick communication and sent clear messages to others without the need for explanation.

The first theory surrounding embodied emotion was the James-Lange theory, and to a certain extent it seems to have dominated thoughts on what emotions really are. The theory states, simply, that emotions are the result of physiological changes in the body, and that different emotions are the result of different changes. So, when you feel angry, there may be cognitive reasons behind it, but the actual emotion is derived from a quickened heart rate, a furrowed brow, and tight lips.

But, this theory hasn't gone undisputed. Cannon and Bard didn't agree with the reductionist view of excluding the brain's role in emotions, and argued that the James-Lange theory was flawed. But, it was their logic that was more flawed. They argued that the brain must be involved, because separating the brain and viscera didn't stop self-reported emotions. But, it did reduce them. Their second criticism was that bodily changes are slow, but emotions are quick. Neurons send messages in milliseconds, and some hormones act in seconds or minutes. Not their best avenue for criticism, but to be fair, it was before we knew much about neuronal firing and endocrinology. They then argued that bodily changes aren't emotion-specific. Whilst this is probably their strongest argument, emotions are pretty specific. We know when we're feeling angry compared to sad or fearful or happy. Our bodies do very different things, even if some things overlap, like heart rate quickening.

Though, Cannon and Bard did have a point. There does appear to be some role of cognition in emotions, and they are consistently linked in many ways.

Russell (1980) argued that emotions can be whittled down to two dimensions: valence, and arousal. Whilst physiological changes are necessary for the arousal bit, it's the context, our thoughts and experiences, which decide if something is negative or positive. Without context, it's pretty difficult to argue that the symptoms of an emotion itself are enough to call it an emotion; they are partially evaluative, after all. What one person finds exciting, one person might find it terrifying - just like a good old horror film.

So, where does that leave us? Next time someone asks how you're feeling, do you check in with your body, or your mind?

My advice? Both. The middle ground is definitely the better option.