What is it that separates the intelligence of humans from that of the animals? We humans are, in so many ways, completely different from the rest of the natural world – and IQ tests prove we are capable of incredible feats of cognition and intelligence – and yet the question of how we are so different has puzzled scientists for centuries.
According to the latest research coming out of MIT, the secret of human intelligence comes down to the number of neurons in our brains. What’s more, it’s not just that we have more neurons than animals (which we do, by a considerable distance), it’s how those neurons actually work to our benefit.
Neurons, Dendrites, and Advanced Human Intelligence
Human neurons feature more electrical compartmentalisation than that found in animal brains. According to scientists, this allows these units to behave in a more independent manner, thus increasing computational capabilities, and allowing single neurons to perform at a higher, more efficient level.
What’s more, structures known as dendrites (which branch out from the neuron and conduct information in the form of electric signals) allow the neurons to constantly communicate with one another, thus controlling thoughts, memories, and behaviours. As electrical signals move through the dendrites and away from the body of the cells, however, they become weaker.
Scientists have spent years studying dendrite length and how their length influences electrical properties. In comparative studies featuring both rats and humans, key differences were found which begin to shed light on the nature of human intelligence. Within human brains, the dendrites were found to be considerably longer. This is due to the fact that the human cortex is much thicker than that found in most animals – the human cortex takes up 75% of brain volume, while in rates, it’s only 30%.
Beside this structural difference, however, the organisation of human and rat brains is actually quite similar; both have six layers of neutrons, and the fifth layers contain dendrites which actually extend through the cortex to the first.
Testing the Nature of Intelligence
In groundbreaking research, a process known as patch-clamp electrophysiology allowed scientists to observe how signals would travel along the dendrites of their test subjects. Because dendrites in the human brain have to be longer in length to reach from the first to the fifth layer, they were found to transmit a weaker signal than those in rat brains. The scientists believe that this difference in electrical activity is the key to unlock the secret of human intelligence in comparison to animal cognitive function… although quite where the connection lies is still something of a mystery.
During the same research, it was discovered that the density of ion channels controlling the flow of electrical current was also considerably different in rats and humans. Human samples proved to have lower density channels, again pointing to a massive difference regarding how human and animal brains function.
Time will tell what these studies will reveal about the nature of human intelligence – and what secrets lie in the way our brains function in every aspect of our lives.