Humans are vain creatures and we like to think we are very clever, and concentrate on what we can do. However to understand how our intelligence evolved we actual need to look at our in-built mental weaknesses.
The reason for this is that the Blind Watchmaker of evolution does not plan ahead and often the results seem to be far from optimum. For instance the nerves in the human eye are at the front of the retina and mean that there is a blind spot in our vision. Our vagus nerve takes a roundabout route rather that taking the shortest path – and this becomes ridiculously long in an animal such as the giraffe.
Similar defects apply to our minds. The short term memory is surprisingly small while our long term memory is unreliable. We think more slowly when processing negative ideas, and suffer from confirmation bias. Unless taught our logical skills have limitations, common sense is not always the most appropriate answer, and we are bad at handling numbers and even worse with more abstract mathematical concepts. We are also too keen to follow charismatic leaders without stopping to check whether their rhetoric makes sense.
The important thing to realize is that these limitations are caused because we are using our “animal brains” in novel ways and defects which were minor at the animal level have started to become significant.
The following draft notes suggest the main steps involved in the evolution of human intelligence starting with the simplest possible animal brain, and how what happened millions of years ago has put restraints on what our brains can do.