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Our Amazing Brains: It’s All About Connections
By Shlomo Maital
Synapses: human brain
Some truly amazing facts emerged from a Horizon documentary featuring British anatomist Professor Alice Roberts.
- We humans share 99% of our genes with chimpanzees. In fact, we are more closely related to chimpanzees, genetically, than chimpanzees are related to, say, gorillas.
- Our brains are very large, relatively. The brain weighs about 3 pounds (1.4 kilo), and has a volume of about 1,200 cm3. But it is not just the size that matters. What makes us smarter than chimps is the connections! A human brain has 100 billion neurons, or nerve cells. These neurons are connected by synapses. There are at least 100 trillion synapses, and maybe as many as 1,000 trillion. That means each neuron is connected to at least 1,000 other neurons, and maybe 10,000.
- It is these connections that are crucial. The internal network of the brain is what makes us creative, able to think and reason, to link ideas together, and to imagine things that do not yet exist.
- According to Prof. Walker, geneticists have discovered a key gene, that differentiates between our brains and that of the chimpanzees. This gene controls the size and number of the synapses, or network connections. Chimps have one such gene. Humans have four of them. When the researchers genetically inserted the gene into mice, the synapses of the mice became thicker and more numerous. So — humans have evolved to be smarter than chimps, because we have these four powerful genes that build our brainy networks.
- Brains are ‘neuroplastic’. If part of the brain is damaged, by stroke for instance, other parts can compensate. To some extent, the brain can reinvent itself, to do tasks normally assigned to brain parts that have been damaged.
- Walker, an anatomist, dispels the “obstetric paradox” — women’s pelvis must be wide enough to permit birth, but not so wide as to hinder mobility, walking and running. Researchers have shown that in fact, the female pelvis, though angled wider than that of the male, is highly efficient in walking and running. So why then are babies born at 9 months? There is another reason.
- Babies consume large amounts of energy. Mothers’ ability to supply that energy continually grows, to meet the embryo’s needs – but the rate of growth slows. At 9 months, the ability of the mother to supply energy to the fetus exactly equals the needs of the fetus for energy. If birth were delayed, the fetus would be starved. So nature conspires to initiate birth, right when the supply and demand of fetal energy match.
Humans have one more advantage over chimps, according to the Horizon documentary. Humans cooperate altruistically. Chimps cooperate too, but only to get an individual reward. Human children, even very young ones, cooperate, and then share rewards, if the rewards are given unequally (more to one child than to another).
This innate sense of fairness exists in children – but, in modern capitalism, seems to disappear. The very wealthy seem to believe they somehow deserve vast wealth. How then do we restore the innate sense of fairness that exists among young children?
BBC: Origins of US (Horizon).