Humans have two decision-making parts in their brains, the cortex and the sub-cortical system. The cortex is a slow machine. It's that part of the brain that likes to take it slow, and gather information before making a decision.

The sub-cortical system is what we're interested in right now though. This other decision-making system is the older part of the brain in our evolutionary history. This part of the brain processes information quickly, but very inaccurately.

The sub-cortical system's primary use is to make us react in dangerous situations, a throwback from those times before the can opener was invented, and we had to hunt for food on the Savannah rather than the supermarket aisle.

Now chances are, if you're reading this, you are not part of the human population that has to use a spear to search for food. A major part of the human populace faces less and less "dangerous" situations, like fighting a hyena for food. Well, we still have to watch out for speeding cars and such, but what if that danger is also eliminated?

What I'm getting at is, if dangers to humans (the kind that demand split-second decision making) are eliminated one by one, and we use the sub-cortical system less and less, will evolution cause us to lose it, and thus end up with smaller brains?

Maybe we'll even end up as a race of Krangs or something, creatures of pure brain matter fighting over-sized turtles. (Hopefully, there won't be any Hannibal Lecters in that future).

Pete Trimmer, author of a new study from the University of Bristol, explored this question and came up with this answer: no. "If humans continue to live in a world of dangers such as wild animals or fast-moving cars, there will still be an evolutionary benefit to maintaining the sub-cortical system."

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