Evolution of intelligence

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The growth in the size of the brain (although not strictly proportional to intelligence) and the increased intelligence of mankind, are believed by some to be caused by the preferential reproductive selection of groups with the ability to use tools and language. Groups with a 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 debate over the possibility that present complex societies that protect the less intellectually endowed will retard the further evolution of intelligence.

[edit] Further development of eye and vision

Mammals developed an outstanding sight, especially the primate species because they lived in trees and had to develop accurate 3D vision for seeing and grasping branches and colour vision for finding colourful fruits between tree leaves.

[edit] Origin of mirror neurons

Mirror neurons are brain cells that fire or are active by seeing or making a movement. They enable animals to learn from each other. Thanks to mirror neurons culture can be made possible, because culture can be defined as learning social actions and conduct from other group members. Learning language is also possible due to mirror neurons, because these neurons fire by hearing, seeing and doing the same movement. It is clear that mirror neurons are very useful in already extremely social groups (e.g. primates, humans or wolves).

[edit] Opposable thumb hypothesis

One possible chain of events leading to human intelligence is as follows:

1) Tree dwelling mammals had a need to better hang onto tree branches. This led to the development of opposable thumbs in primates. Opposable thumbs were useful for other purposes, such as holding a tree branch to be used as a club. However, the utility of the opposable thumb was limited by the need to walk on all four hands/feet.

2) At his time, our ancestors moved to a savanna environment with fewer trees and more open space. These factors drove the development of an upright walking ability in certain primates to facilitate crossing open spaces and more fully utilize opposable thumbs for tool use. (While most developed in humans, many other primates also have the ability to walk upright for short times.)

3) The availability of opposable thumbs, now freed from the task of walking, made them usable for a wide range of tools. However, the limiting factor was now primate intelligence, which was insufficient to fully utilize this ability.

The use of tools in foraging and hunting was one of the factors that led to the development of vastly increased intelligence in hominids, which utilized this new tool making ability to far greater extents to than previously achieved. One effect was to make other primates less able to compete with hominids. Thus, other primates generally only survived when they occupied a different ecological niche from hominids, such as the tree canopy.

4) Hominids couldn't typically outrun either prey or predators, due to their upright stance. Thus, intelligence became necessary for survival, by allowing for the setting of traps, use of weapons, communication of location and number of prey or predators in the area, etc.

5) Eventually the most intelligent of the hominids, homo sapiens sapiens (modern humans), outcompeted the other hominids and forced their extinction.