Evolution of intelligence

The growth in the size of the brain and the increased intelligence of man, is believed by some to be caused by the preferential reproductive selection of groups with the ability to use tools and use language. Using tools and language increased the survival rate of those groups with larger or more efficient brains. Groups with greater ability to use tools and language may have had an evolutionary reproductive advantage, thus leading to natural selection of those groups. There is a possibility that present complex societies that protect the less endowed and eliminate individuals irrationally by war and other seemingly irrational actions will prevent intelligence from evolving further.