P E T S sedentary mates. These factors exist in all species and are called ’miracle-growth factors for the brain’ by some scientists because they stimulate the formation of new connective bridges between nervous cells from scratch, potentiating the brain activity at any age. Even gentle physical activities increase the connectivity and boost memory. This body-mind connection is rooted in the evolutionary memory of all creatures. Probably the brain boost mediated by growth factors emerged to improved orientation during foraging activities. When animals forage there is an automatic cerebral production of growth factors that accompany their wandering, which in origin was probably an accidental by-product of the evolution lately turning an important survival strategy. In fact growth factors stimulate the neural and synaptic growth of cerebral cells, helping animals to remember the paths and the best pastures, so they can revisit the locations in the near and remote future. A study which followed 1500 people for 20 years came to the conclusion that these effects are long lasting because those who exercised at least twice a week during their middle age were less prone to develop dementia in their 70s. Human mysteries Physical agility, rapidity of reaction and performance are strictly linked to the activity of trained brains in humans, but with some differences compared to animals. Younger people and athletes react more quickly than older and sedentary potato coaches. Mysterious turning points in our prehistory proved determinant in the creation of a brain- body link. Our ancestors accidentally trained as long-distance runners because of their need to forage and hunt big prey: gazelles, antelopes, deer and buffalo, even horses. Trekking faraway to catch their food, they would have experienced that increased surge of neurotransmitters, serotonin, noradrenaline, dopamine, and growth factors, BDNF, IGF1, that ultimately led to the appearance of intelligence. It is not only a matter of muscles, resistance and strength. Mental activity is fundamental in boosting performances and vice versa is also true, because exercise is an enhancer of normal cognition. Decline in fitness explains why some people are more prone to dementia, but this was not so obvious in the recent past. A link between physical fitness and mental brightness was first suggested during the 1960s but it was only in the 1990s that the California- born geneticist Fred Gage realised that exercise helps the growth of neurons. Exercise Research The authors of an article published in Nature at about the same time observed that sedentary people given a boost of exercise for 6 months had better cognitive skills compared to controls who did not exercise, thus they became more intelligent. Regular training can influence performances in mature and even elderly people and animals reducing reaction times and increasing resistance. Marathon brains An active brain requires a lot of nutrients, oxygen and at least 20% of daily calories. Exercise helps to build the neuronal capillary network and its maintenance. By reducing blood pressure, regular physical activity protects the brain arteries and provides a steady supply of nutrients. Exercise regulates the signalling activity of neurotransmitters and cuts the risk of Alzheimer’s, a disease associated with the formation of fatty plaques, nicknamed ‘diabetes of the brain’, that causes brain damage by altering the brain insulin system. Alongside these dreadful effects due to lack of exercise, for reasons that are still debatable, we hold far better athletic endurance than most animals and certainly more than our primate cousins. A chimpanzee or a gorilla would never run a marathon. Some would argue that healthy animals including humans, generally 47