Did you know that our DNA only differs from chimpanzees by two percent? That’s right. We share 98 percent of our DNA with our furry cousins that swing from trees. So, what is it exactly that makes us human and keeps them being primates?
As part of the human genome project, scientists have identified which genes set us apart. Turns out that one of them is the regulatory gene that determines how many neurons humans make and when the neuron producing process stops.
The Total Number of Neurons Matters
Human neurons are fundamentally identical to those of chimpanzees and even those of marine snails. The big difference is in the total number of neurons each organism ends up making. Humans produce about 100 billion neurons. Stopping earlier, chimpanzees have brains about one-third the number.
Each neuron makes thousands of connections. This leads to the possibility of a staggering amount of neural circuits in the human brain. The most recent studies put the number around 86 billion neurons. This huge number of connections allows the human brain to be so complex and capable of performing an impressively vast array of mental functions and behaviors.
The astronomical number of connections also explains how the brain is capable of massive change through neuroplasticity, which is the ability of the brain to physically change form and function based on experiences, behaviors, and thoughts. Before the discovery and acceptance of neuroplasticity, it was widely believed that the only way for the brain to change was through the slow process of evolution. Now, we know that your brain changes from birth until death.
Neuroplasticity Allows the Human Brain to Evolve
Plasticity confirms a way for the brain to change and evolve other than genetic mutation. For example, when a person learns to read, the biological structure of their brain is altered. Reading is taught to the next generation and, subsequently, impacts their brains and so on.
However, the process of learning to read not only modifies the brain circuits in one area of the brain but also many areas connected to the ones employed to read. Because of this, plastic change tends to “flow” through the brain. When areas of the brain are linked together in a new way by a new activity, the brain modules involved are altered by the interaction. Synergistically, a new brain with greater capabilities is formed.
Plasticity Yields a Civilized Brain
This neuroplastic process may explain how our hunter-gatherer brain and more cognitive-cerebral brain work together to make us “civilized.” Becoming civilized is fundamentally a process of learning to restrain or channel brute predatory and dominance instincts into acceptable expressions such as contact sports, board and computer games, art, and literature.
The basic instincts still exist — as demonstrated by a fan yelling “Kill him!” at a football game. Yet, when the instinct to stalk prey is linked to activity with rules and acceptable behaviors, the neuronal networks are also linked and alter and temper each other. Accepted culture is a series of processes where the hunter-gatherer’s brain teaches itself to rewire itself. Our plastic brains can always allow functions that have come together to separate. Because of this, regression is always possible and civilization is always only one generation deep.
image source: https://www.flickr.com/photos/thebusybrain/