Researchers wonder why the human race is so clever. Some believe that cooking food (in the last few hundred thousand years) improved nutrition so much that a big leap forward was taken. A cooked potato is much more nutritious than a raw one. Maybe it was the discovery of agriculture that nourished our intelligence. Or, maybe it was that thanks to agriculture cities sprung up (without agriculture it would have been impossible to feed many people all living in a small area). Cities offer opportunities and require organizational solutions that set loose intelligence. When we say that someone is intelligent, we usually mean that he/she is good at solving problems, or taking decisions or has a high IQ. However, from the biological point of view we know very little and we don’t even know the difference between the brain of a very intelligent person and that of a normally intelligent person. We know that the brain is modular which means that the different areas each have areas of competence and that these areas must communicate through neurological circuits. We don’t know how the different areas establish priorities. For example, the occipital area deals with visual info that comes from the eyes and this info has to be classified and integrated with info we have in our memory or maybe comes from other areas. So, even if we don’t have memories of encounters with lions, we know we should not pull their tail. We know that guns are dangerous only if loaded. What coordinates all this info that comes from the various brain regions so that we give adequate responses to the visual, auditory, tactile and olfactory stimuli we receive? The reply is in the type of connection. There are fixed or crystallized strong connections that have been tried out over the years and there are weak connections that form when we face new situations. The more we form new circuits in response to new circumstances such as learning to make the new dishwasher work, or study a language, or sing a new song or make risotto for the first time, the more intelligent we are. Kids easily form new weak connections and the ability can be promoted through practice. Repetitive experiences penalize the formation of new weak connections whereas always new situations penalize that of strong connections. A balance is the best advice. Therefore, go and ski every Sunday but not always in the same place with the same people on the same runs.