The evolutionary history of humans explains why movement and physical activity have been important for function and health brain. In the few more than half a million years that we were hunter-gatherers, moving well and fast increased our chances for survive. In that period the motor cortex in the brain grew upwards, which led to an improvement in our movements and also in our cognitive abilities. It is very likely that without this movement we would not be the thinking beings we are today.
Our ancestors lived in trees, moved little, ate mainly vegetables and used their arms and legs to get around. Probably due to some drastic climate change that cooled the environment considerably, some hominids went from a more sedentary life to having to descend into the savannah and move long distances searching food. They became hunter-gatherers. As they were forced to come down to the ground and found that the savannah vegetation prevented them from seeing for long distances, they began the slow process of standing upright and walking on their hind legs.
According to a Royal Society of London study based on prehistoric Laetoli footprints found in Tanzania, hominins developed the ability to walk upright some 3.7 million years ago (Australopitecus afarensis). Analysis of these remains suggests that Australopithecus walked more like a modern human than any bipedal primate. More than 2 million years may have passed from the time when walking on both hind limbs was initiated to the time when an upright gait was achieved. And for many anthropologists what made us human was to start walking upright.
In this evolution from four-limbed movement to bipedal posture, they had to face moments of imbalance and precarious balance on only one support instead of 2 or 3 supports like the other apes. Constant adjustments had to be made to movements and postures until a large amount of information had to be coordinated in order to maintain balance and to master movement in an irregular, changing and increasingly large environment. Life incorporated higher levels of aerobic activity. This information processing and adjustment must have been a major cognitive challenge that pushed his brain development far beyond that of our ape ancestors.
Part of human brain development has come from the feet. These motor actions had their effect on the brains of different species. There were changes in brain volume, probably due to their increased level of stimulation, and in the level of blood flow due to an increase in brain metabolism. Brain volume is the main element that allows us to analyse the evolution of the brain and our cognitive capacity. Although it is a partial measure because it is a quantitative figure and the capacity of our brain is established more on qualitative parameters, it is a measure that gives us a reliable correlation on the increase of brain functionality.
Australopithecus was the first bipedal hominid and reached skulls of 500 cm3 similar to those of the great apes. Then came the first of the Genus Homo, Homo habilis, who were opportunistic omnivores like Australopithecus but in addition to walking he also built lithic tools. It reached a cranial capacity of more than 700 cm3, so its intelligence should be similar.
Homo Habilis evolved into new species of the Genus Homo. The Homo Erectus that mastered fire and created complex tools already reached a cranial capacity of 1000 cm3, twice that of the great apes and Australopithecus.
About 195,000 years ago, our species, Homo sapiens, appeared, reaching a staggering cranial capacity of 1,400 cm3 and with a sixfold increase in blood supply compared to the 1st hominids.
The humanisation process of the brain of Homo sapiens turned it into a unique and different organ, due to its structural and functional complexity and its relative size. Standing and walking profoundly influenced our organism and especially our brain. It was certainly not the only factor. But the fact that the development of this posture and movement went hand in hand with the increase in cranial capacity and irrigation gives us an idea how movement and human brain evolution are strongly related.
The evolution of the human brain over millions of years has allowed us to develop much higher levels of intelligence than any other species, including that of other primates that at one time had the same brain capacity as humans. Movement made us smarter. After all, movement was the first great cognitive challenge that the genus homo had to face in order to differentiate itself from other living beings, producing very high levels of intelligence.
It is through movement that we can exert some influence on the environment. By influencing the environment we are in turn influencing the brain because its functions depend on the stimuli it perceives from the environment. Therefore, we have the option of being able to stimulate the brain through movement.
“In my opinion, the greatest mistake I have made has been not to attach sufficient value to the direct influence of environment independently of the process of natural selection. When I wrote “The Origin”, and for several years afterwards, I could not find the slightest evidence for the direct action of environment; now there is an enormous amount of evidence”
(Letter from Charles Darwin to Moritz Wagner, 1876