LIFE SCIENCE

Detailed explanation-1: -Over the last million years of evolution, our brain underwent a considerable increase in size and complexity, resulting in the exceptional cognitive abilities of the human species. This brain enlargement is largely due to an increase in the number of neurons in the cerebral cortex, the outer part of the brain.

Detailed explanation-2: -Relative brain size of Homo did not change from 1.8 to 0.6 mya. After about 600 kya it increased until about 35, 000 years ago, when it began to decrease. Worldwide, average body size also decreased in H.

Detailed explanation-3: -Brain size increased rapidly during human evolution due to the expansion of many brain regions, resulting in human brains being exceptionally larger than those of our closest relatives.

Detailed explanation-4: -Human brain size nearly quadrupled in the six million years since Homo last shared a common ancestor with chimpanzees, but human brains are thought to have decreased in volume since the end of the last Ice Age. The timing and reason for this decrease is enigmatic.