Evolution of human intelligence

Chimpanzees can make tools and use them to acquire foods and for social displays; they have mildly complex hunting strategies requiring cooperation, influence and rank; they are status conscious, manipulative and capable of deception; they can learn to use symbols and understand aspects of human language including some relational syntax, concepts of number and numerical sequence.

[2] One common characteristic that is present in species of "high degree intelligence" (i.e. dolphins, great apes, and humans - Homo sapiens) is a brain of enlarged size.

One consequence of this was that the north African tropical forest began to retreat, being replaced first by open grasslands and eventually by desert (the modern Sahara).

At some point the bipedal primates developed handedness, giving them the ability to pick up sticks, bones and stones and use them as weapons, or as tools for tasks such as killing smaller animals, cracking nuts, or cutting up carcasses.

History of humans In the Late Pliocene, hominins were set apart from modern great apes and other closely related organisms by the anatomical evolutionary changes resulting in bipedalism, or the ability to walk upright.

Paleo-anthropologists from the past half-century have had the tendency of reducing stone tool artifacts to physical products of the metaphysical activity taking place in the brains of hominins.

The development of stone tool technology suggests that our ancestors had the ability to hit cores with precision, taking into account the force and angle of the strike, and the cognitive planning and capacity to envision a desired outcome.

[11] Acheulean culture, associated with Homo erectus, is composed of bifacial, or double-sided, hand-axes, that "requires more planning and skill on the part of the toolmaker; he or she would need to be aware of principles of symmetry".

In combination with other data, the formation of this tool culture for hunting large mammals in groups evidences the development of speech for communication and complex planning capabilities.

There are several styles associated with this category of the Upper Paleolithic, such as blades, boomerangs, atlatls (spear throwers), and archery made from varying materials of stone, bone, teeth, and shell.

The cerebral cortex is significantly larger in humans than in any other animal and is responsible for higher thought processes such as reasoning, abstract thinking, and decision making.

These group dynamics relate to Theory of Mind or the ability to understand the thoughts and emotions of others, though Dunbar himself admits in the same book that it is not the flocking itself that causes intelligence to evolve (as shown by ruminants).

[28] Insects provide an opportunity to explore this since they exhibit an unparalleled diversity of social forms to permanent colonies containing many individuals working together as a collective organism and have evolved an impressive range of cognitive skills despite their small nervous systems.

This was one of the first studies to show evidence for the cultural intelligence hypothesis in a non human species- frequency of learning opportunities had gradually produced differences in cognitive abilities between the two species.

This change separated us from other species of monkeys and primates, where this aggressivity is still in plain sight, and eventually lead to the development of quintessential human traits such as empathy, social cognition, and culture.

[49][50] This theory has received strong support from studies of animal domestication where selective breeding for tameness has, in only a few generations, led to the emergence of impressive "humanlike" abilities.

[69] In response to Kanazawa's 2010 article, psychologists Scott Barry Kaufman, Colin G. DeYoung, Deirdre Reis, and Jeremy R. Gray gave 112 subjects a 70-item computerized version of the Wason selection task (a logic puzzle) in a social relations context as proposed by Leda Cosmides and John Tooby in The Adapted Mind,[70] and found instead that "performance on non-arbitrary, evolutionarily familiar problems is more strongly related to general intelligence than performance on arbitrary, evolutionarily novel problems".

[70] Despite other experimenters finding that some contexts elicited more correct subject responses than others, no theoretical explanation for differentiating between them was identified until Tooby and Cosmides proposed that disparities in subjects performance on contextualized versus non-contextualized variations of the task was a by-product of a specialized cheater-detection module, and Tooby and Cosmides later noted that whether there are evolved cognitive mechanisms for the content-blind rules of logical inference is disputed.

Hunt noted in 2011 that no genes related to differences in cognitive skills across various racial and ethnic groups had ever been discovered,[80] and in 2012, American Psychologist published a review of new findings by psychologists Richard E. Nisbett, Joshua Aronson, Clancy Blair, Diane F. Halpern, and Eric Turkheimer, economist William Dickens, and philosopher James R. Flynn that concluded that almost no single-nucleotide genetic polymorphisms that have been discovered are consistently associated with variation in IQ in the normal range.

[91] Additionally, Nesse and theoretical biologist Mary Jane West-Eberhard view sexual selection as a subcategory of social selection,[list 2] with Nesse and anthropologist Christopher Boehm arguing further that altruism in humans held fitness advantages that enabled evolutionarily extraordinary cooperativeness and the human capability of creating culture, as well as capital punishment by band societies against bullies, thieves, free-riders, and psychopaths.

[82] Sexual selection is often thought to be a likely explanation for other female-specific human traits, for example breasts and buttocks far larger in proportion to total body size than those found in related species of ape.

[82] The sexual selection by the disability principle/fitness display model of the evolution of human intelligence is criticized by certain researchers for issues of timing of the costs relative to reproductive age.

[106][107] The number of people with severe cognitive impairment caused by childhood viral infections like meningitis, protists like Toxoplasma and Plasmodium, and animal parasites like intestinal worms and schistosomes is estimated to be in the hundreds of millions.

[108] Even more people with moderate mental damages, such as an inability to complete difficult tasks, that are not classified as 'diseases' by medical standards, may still be considered as inferior mates by potential sexual partners.

[citation needed] Another model describing the evolution of human intelligence is ecological dominance-social competition (EDSC),[109] explained by Mark V. Flinn, David C. Geary and Carol V. Ward based mainly on work by Richard D. Alexander.

As a result, the primary selective pressure for increasing human intelligence shifted from learning to master the natural world to competition for dominance among members or groups of its own species.

[22] Early hominins dating back to pre 3.5 Ma in Africa ate primarily plant foods supplemented by insects and scavenged meat.

[10] Their diets are evidenced by their 'robust' dento-facial features of small canines, large molars, and enlarged masticatory muscles that allowed them to chew through tough plant fibers.

[10] There is no direct evidence of the role of nutrition in the evolution of intelligence dating back to Homo erectus, contrary to dominant narratives in paleontology that link meat-eating to the appearance of modern human features such as a larger brain.

[126] Diets deficient in iron, zinc, protein, iodine, B vitamins, omega 3 fatty acids, magnesium and other nutrients can result in lower intelligence[127] either in the mother during pregnancy or in the child during development.