Question

Which explanation is most likely the reason for the evolution of a larger brain in humans?
The size of the human brain increases the more it is used.
A larger brain allows humans to solve complex problems.
The size of the human brain has changed randomly over time due to mutations.
A large brain increases humans’ ability to fight and survive disease.

Answer 1

the second sentence.

Answer 2

There is strong evidence that an increased brain size was only able to occur due to a muscle deficiency disorder. In other primates the skull hardens and fuses rapidly because of a very large muscle group that give primates a strong jaw, but attaches to the skull. This means the skull is under extreme stress and must harden quickly, but in humans that muscle does not develop as much and the skull does not need to harden as quickly.