As humans, we share the brain of snakes and lizards, but have evolved to a higher state, capable of cognitive thought, choices and decisions. In the 1960s, neurologist Paul MacLean proposed that our skull holds not one brain, but three, each representing a distinct phase of evolutionary development. He called his theory the "triune brain." MacLean says that three brains operate like "three interconnected biological computers, each with its own special intelligence, its own subjectivity, its own sense of time and space and its own memory. He refers to these three brains as the neocortex or neo-mammalian brain, the limbic or mammalian system, and the reptilian brain, the brainstem and cerebellum. Each of the three brains is connected by nerves to the other two, but each seems to operate as its own brain system with distinct capacities. Innermost in our brain is the reptilian brain, its oldest and most primitive part. The reptilian brain appears to be largely unchanged by evolution and we share it with all other animals which have a backbone. This reptilian brain controls body functions required for sustaining life such as breathing and body temperature. At this level of evolution, behaviour relating to survival of the species, such as sexual behaviour and catching prey is instinctive and responses are automatic. Territory is acquired by force and defended. Might is right. The python is wired to survive and will attack if threatened or seeking prey. In the wild, reptiles are independent immediately from birth fully adapted to their environment from the offset. I am not a snake breeder, but from a brain perspective, I am pretty sure the python wasn’t sulking as there was no effort at a relationship. I am also convinced that a tank in the corner of a boy’s bedroom in west London isn’t the most natural environment. I am however very interested in human survival instincts and use of our reptilian brain so would appreciate any thoughts.