When a male vole repeatedly mates with a female, a hormone called vasopressin is released in his brain. The vasopressin binds to receptors in a part of the brain called the nucleus accumbens, and the binding mediates a pleasurable feeling that becomes associated with that female. This locks in the monogamy, which is known as pair-bonding. If you block this hormone, the pair-bonding goes away.

If an epileptic seizure is focused in a particular sweet spot in the temporal lobe, a person won´t have motor seizures, but instead something more subtle. The effect is something like a cognitive seizure, marked by changes of personality, hyperreligiosity (an obsession with religion and feelings of religious certainity), hypergraphia (extensive writing on a subject, usually about religion), the false sense of an external presence, and, often, the hearing voices that are attributed to a god. Some fraction of history´s prophets, martyrs, and leaders appear to have had temporal lobe epilepsy.

If our brains were simple enough to be understood, we wouldn't be smart enough to understand them.

Who you are depends on the sum total of your neurobiology.

You are more likely to believe that a statement is true if you have heard it before - whether or not it is actually true.

We are made up of an entire parliament of pieces and parts and subsystems. Beyond a collection of local expert systems, we are collections of overlapping, ceaselessly reinvented mechanism, a group of competing factions. The conscious mind fabricates stories to explain the sometimes inexplicable dynamics of the subsystem inside brain. It can be disquieting to consider the extent to which all of our actions are driven by hardwired systems doing what they do best while we overlay stories about choices.

You are part of a complex social network that changes your biology with every interaction, and which your actions can change.