▶ Your Answer :
According to the reading, there are several plausible explanations for shrinking brain. However, the lecturer argues that these are unsatisfactory.
First, the reading says that this is because human society has changed. In the past, human beings lived in small groups, they had to deal with everything that related to themselves. However, a big brain became less needed as the communities get bigger. On the other hand, the lecturer contends that this theory cannot explain this phenomenon. Since our society has developed, new intelligence is required, such as social intelligence. Also, high technology and relationships between people made our brain to process more tasks.
Next, the reading claims that reduced size of the brain was resulted from decrease in body size. People in the early days had larger body than today. A big brain was wanted for a big body. In addition, due to greater amount of skin surface, brain had to handle more information. In contrast, the lecturer maintains that this is not true. A study with human fossils showed that brain size decreased much faster that body size did. If the body size was the causation of diminishing brain, they should have reduced in the same rate.
Finally, shrinking visual cortex may be the reason for this occurrence. When human beings survived themselves by hunting, they needed more visual accuracy. But in sedentary lifestyles, it was not required. While the lecturer asserts that this is not a main reason, suggesting that visual cortex only takes up the smallest part of the brain cortex, so it cannot have significant impact on the entire brain. What's more, other parts of the brain is declining as well. Thus, it cannot be said that visual cortex influenced the brain size. |