What sets the human brain apart?
We need to take a whistle-stop tour of the brain’s evolution to answer that. In simple terms, the brain has three layers. The first is the reptilian brain. Reptiles have been on the planet for 300 million years and they’re hardwired to survive. The second layer, the mammalian brain, emerged 200 million years ago. What does the brain of a mammal have that a reptile doesn’t? Answer: social connections, emotions. The final brain layer, the neocortex, is what differentiates us from most animals. It’s the biggest, most flexible part of the brain and has almost infinite learning abilities. It’s responsible for the development of human culture, language and what we call “executive function”.
How does the brain’s evolution affect the way we think?
Trying to find lunch rather than be lunch is one of the brain’s key drivers. The first brain truth, therefore, is that even though we like to think human beings are rational, we are mostly negative and paranoid. Danger is our default setting. The average person spends 95% of their day going through repeat thoughts. Worse, an average 75% are repeat negative things, just 20% on positive repeat thoughts and only a tiny 5% on new ideas.
Enter another brain truth: when the brain is left idle, its go-to state is social thoughts. Relying on others is what helped us survive when we were born. Think how easy gossiping or moaning seems. It is much easier to do and consumes far less energy than, say, solving a problem. What do we do when we’re bored or tired? We aimlessly swipe our phones checking Facebook posts or watching YouTube videos.
Is it possible to change the way our brains are wired?
We absolutely can change. The brain continuously reorganises itself by forming new neural connections, a process called neuroplasticity, which allows the neurons to respond to new situations or environmental changes. These new connections create fresh neural pathways.
On average, we each have around 86 billion neurons. What’s interesting is that this number doesn’t change: we have roughly the same number of neurons when we die as we did when we were born. What changes is the number of connections between them. We are born with billions of neurons, but few connections. More connections develop along our neural pathways as we start to grow. Then, as we mature, the brain starts specialising and says, “You know what? I think this particular pathway is more helpful” and starts reducing the number of connections. Much of this judgement happens when we are small and haven’t developed the capacity to judge – we just differentiate between things that give us pleasure or pain – and that becomes our model of the world.
Neuroscientist David Eagleman puts it: “We become who we are not because of what grows but what is removed in our brain.” Meaning that in the first two years of our lives the neuron branches grow and the cells become increasingly connected. In adulthood, we lose the connections that we don’t use: the connections we have become fewer and therefore stronger. We have to work hard and get our brains to believe a different story and create new neural pathways.
Imagine you had a huge Scrabble board with millions of letters. Your brain acts as a filter. You can choose which letters you allow in and you can play with how you put them together, creating a completely different version of your life. But that takes energy.
Is preserving energy the name of the game?
The brain contributes to just 2% of our body weight yet consumes 20% of our energy. Preserving energy, therefore, is the name of the game.