V.S. Ramachandran, in his book The Tell-Tale Brain, describes the sudden increase in human intelligence that occurred a hundred and fifty thousand years or so ago as a phase transition.
A phase transition is a sudden change of something from one state to another state, rather than a gradual alteration.
Ramachandran gives the change of ice into liquid water as an example of a phase change. At -5 degrees Celsius, for instance, water exists in the form of ice. If the ice is warmed up to -4 degrees it is still ice. The only difference is that it is ice that is one degree warmer. Warm it up to -3 degrees, -2 degrees or -1 degree Celsius and the same applies. The ice stays as ice. Warm it up to 0 degrees Celcius however and the ice suddenly changes. It changes into liquid water. A fraction of a degree below zero it’s ice: a fraction of a degree above zero it’s water. As the substance’s temperature crosses that boundary it experiences a phase transition.
Ramachandran’s contention is that hundred and fifty thousand years or so ago the human brain was evolving away in the normal manner of evolution, along with the brains of the other apes (and for that matter the brains of everything else that had brains), with a minor change here, an incremental variation there – a little like ice getting gradually warmer – when it experienced a phase transition brought about by an alignment of circumstances and conditions.
I’ve devised a graphic to illustrate the concept. The graphic involves metaphor, which is one of the concepts we acquired as a result of the phase transition, so you’ll be able to understand this graphic but your pet dog won’t.
Imagine the brain is a balloon, of the helium-filled or hot air variety.
In our pre-human ancestors the balloon floated above its basket, but it was too small to leave the ground, with the basket staying firmly earthbound. Very very slowly the balloon increased in size. But the basket stayed on the ground.
Eventually a point was reached where the balloon was just big enough for the upward force of the balloon to overcome the downward force of gravity and the balloon rose into the air. The balloon had entered a new way of being. It was airborne.
If the balloon was a fraction smaller it could never become airborne, but at its new slightly larger size it had no option but to become airborne and to float off into the sky. It had experienced a phase transition. It had acquired a new form of intelligence.
About V. S. Ramachandran