cerebrum, which makes up 85 per cent of the brain’s weight. The right cerebral hemisphere is more the creative and emotional; the left deals with logic. The occipital lobe at the back of the cerebrum is devoted to vision; the parietal lobe above deals with movement, position, orientation and calculation. Behind the ears and temples lie the temporal lobes. These deal with sound and speech comprehension. The temporal lobes also include the hippocampus and amygdala, which play pivotal roles in emotion and memory. Further towards the front of the brain are the prefrontal lobes, which deal with the most complex processes of thought: decision-making, planning, working memory, conceptualising, and attention control. They also deal with emotions such as regret, morality and empathy. The prefrontal lobes are part of what makes humans the most intelligent species in the world because they are considered the seat of complex thought. They are also much larger in humans than in other species. But what are the other differences? Eric Holland, a neurosurgeon and cancer biologist at the University of Washington, says that the size and surface area of a brain is the main difference. Humans have more neurons per unit of volume than any other animal, and the only way to do that with the brain’s layered structure is to make folds in the outer layer or cortex. Animals considered to have high intelligence, such as monkeys and dolphins, have these folds; mice and goldfish don’t – their brains are rather smooth. But no animal matches our frontal lobes – those loci of higher- level thinking. The human brain is a fiendishly complex and endlessly interesting organ. It helps us to organise, retrieve and make sense out of the information we process every day. Without our brains, where – or what – would we be?
The human brain is a fiendishly complex and endlessly interesting organ. It helps us to organise, retrieve and make sense of the information we process every day
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