In the given set of information, both the reading and the lecture deal with brain size in human evolution. The lecturer casts doubt on the reading passage's claim on the reasons why human brain size decreased over time, by presenting three counterarguments.
First, the reading passage claims that living in larger communities with specialised division of labor made large mental capacity unnecessary. However, the lecturer claims that the point made in the reading passage is disputable. This is because in the present society, larger mental capacity is required for new inteligence such as social interaction and communication.
Next, according to the reading passage, human brain shrunk with decreasing in body size. However, the lecturer contends that this claim is controversial. To be specific, recent studies proved that brain size shrinks faster than the body size. Thus, the decline in brain size is not correspondent to the decrease in body size.
Lastly, the lecturer disagrees on the reading passage's claim that shrinking visual cortex, the part responsible for processing visual information, accounts for the reduction in brain size. He claims that other parts of the brain must have decreased as the visual cortex is only a small region in the overall size of the body.
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