I’m listening to The Happiness Hypothesis by Jonathan Haidt and it is interesting to see how the Self is derived from a cacophony of minor selves. Every one has felt a will that overrides another within themselves, to consciously wake up early when you’re tired (or not), to take that last bite of a chocolate (or not), and so on.

First there are metaphors, like the Chariot Allegory. In this the soul is a charioteer driving two horses: one, rational and calm; the other, irrational and out-of-control. And of course, Pixar’s Inside Out where emotions are represented as little homunculi inside each person.

Then in a literal sense, there is actually a second brain in our gut. Called the Enteric Nervous System (wiki), it is a massive lining of neurons in our gut that is made of the same neural network as our brains. It can run independently and does not need need instructions from the main brain. More interestingly it has some ties to our emotions as well. For example it can apparently trigger anxiety when there’s a stomach infection. So emotions have chemical and neurological causes outside of just the metaphorical ‘heart’.

Another book, We are our brains, also drove that last point home quite level. That author leans heavily on the nurture side of things, and showed how a large part of a person’s personality is shaped by the brain and hormones. How hormones like oxytocin, prolactin and vasopressin tune how you bond, how you behave with strangers and children. How an underdeveloped pre-frontal cortex leads to greater risk taking behaviour. And so on.

While I’m not an expert in any of these areas, it is fascinating to see how far we’ve come in understanding the interplay of physical, chemical and neurological phenomena in creating the I in all of us.