Bipedal tool-using primates from the subtribe Hominina date back to as far as about 5 to 7 million years ago, such as one of the earliest species, Sahelanthropus tchadensis. Being unprepared for the sudden change in climate, the survivors were those intelligent enough to invent new tools and ways of keeping warm and finding new sources of food (for example, adapting to ocean fishing based on prior fishing skills used in lakes and streams that became frozen). Peacemaking among primates. , Meerkats have far more social relationships than their small brain capacity would suggest. Here they were exposed to predators, such as the big cats, from whom they had previously been safe. It is unclear to what extent these early modern humans had developed language, music, religion, etc.  Thus the direct adaptive benefit of human intelligence is questionable at least in modern societies, while it is difficult to study in prehistoric societies.  Though this becomes a superficial argument after considering the balancing positive selection for the ability to successfully 'make ones case'. On a mechanistic level these changes are believed to be the result of a systemic downregulation of the sympathetic nervous system (the fight-or-flight reflex). The final third of our evolution saw nearly all the action in brain size. According to proponents of the Toba catastrophe theory, the climate in non-tropical regions of the earth experienced a sudden freezing about 70,000 years ago, because of a huge explosion of the Toba volcano that filled the atmosphere with volcanic ash for several years. By Stephen Jay Gould.  Other explanations for the positive correlation between brain size and frugivory highlight how the high-energy, frugivore diet facilitates fetal brain growth and requires spatial mapping to locate the embedded foods. This reduced the human population to less than 10,000 breeding pairs in equatorial Africa, from which all modern humans are descended. Intelligence has evolved many times independently among vertebrates. Since 2005, scientists have been evaluating genomic data on gene variants thought to influence head size, and have found no evidence that those genes are under strong selective pressure in current human populations. If you were to put a mouse brain, a chimp brain and a human brain next to each other and compare them it might seem obvious … This probably happened in the Oligocene period, 35 million years ago. Not only do humans need to determine that the contract was violated, but also if the violation was intentionally done. Here, we use ecologically relevant measures of cognitive ability, the reported incidence of behavioral innovation, social learning, and tool use, to show that brain size and cognitive capacity are indeed correlated. It is crucial to keep in mind that evolution operates within a limited framework at a given point in time. According to the model, human intelligence was able to evolve to significant levels because of the combination of increasing domination over habitat and increasing importance of social interactions. From about 5 million years ago, the hominin brain began to develop rapidly in both size and differentiation of function. Another hypothesis is that it is actually intelligence that causes social relationships to become more complex, because intelligent individuals are more difficult to learn to know. ", "Origins of human intelligence: The chain of tool-making and brain evolution", "Tooth wear and dexterity in Homo erectus", "Earliest evidence of modern human life history in North African early Homo sapiens", "Musical behaviours and the archaeological record: a preliminary study", "The neuroscience of primate intellectual evolution: natural selection and passive and intentional niche construction", "Dolphins and African apes: comparisons of sympatric socio-ecology", "Broca's area homologue in chimpanzees (Pan troglodytes): probabilistic mapping, asymmetry, and comparison to humans", 10.1002/(SICI)1520-6505(1998)6:5<178::AID-EVAN5>3.0.CO;2-8, "Processing power limits social group size: computational evidence for the cognitive costs of sociality", "Comparing Two Methods for Estimating Network Size", "How Much of a Network does the GSS and RSW Dredge Up? A more social and communicative person would be more easily selected. Academic Press, New York and London. The great apes (hominidae) show some cognitive and empathic abilities. Page 51. Allen, Elizabeth, et al.  The human variant of the gene SRGAP2, SRGAP2C, enables greater dendritic spine density which fosters greater neural connections.  It is often assumed that if breasts and buttocks of such large size were necessary for functions such as suckling infants, they would be found in other species. ", "Animal evolution during domestication: the domesticated fox as a model", "Theory of Mind: Towards an Evolutionary Theory", "Colloquium paper: adaptive specializations, social exchange, and the evolution of human intelligence". Since its origins in 1890 as one of the three main divisions of the University of Chicago, The University of Chicago Press has embraced as its mission the obligation to disseminate scholarship of the highest standard and to publish serious works that promote education, foster public understanding, and enrich cultural life. The majority of said changes occur either in terms of size or in terms of developmental timeframes. [letter] New York Review of Books 22 (Nov. 13). Since the disability principle is about selection from disabilities in sexually immature individuals, which increases the offspring's chance of survival to reproductive age, disabilities would be selected against and not for by the above mechanism.  Even more people live with moderate mental damages, such as 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. , Dunbar argues that when the size of a social group increases, the number of different relationships in the group may increase by orders of magnitude. 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). 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. As their environment changed from continuous forest to patches of forest separated by expanses of grassland, some primates adapted to a partly or fully ground-dwelling life. With sexual selection, an unattractive individual is more likely to have access only to an inferior mate who is likely to pass on many deleterious mutations to their joint offspring, who are then less likely to survive.. For some 2 million years, our minds continued to expand.  Researchers have attributed hominin evolution to mosaic evolution. "Ecological dominance, social competition, and coalitionary arms races: Why humans evolved extraordinary intelligence", "Metabolic costs of brain size evolution", "Chapter 9: Myth and Mystification: The Science of Race and IQ", "Human evolution expanded brains to increase expertise capacity, not IQ", "Mosaic evolution and the pattern of transitions in the hominin lineage", "The Wernicke area: Modern evidence and a reinterpretation", "The Roots of Alzheimer's Disease: Are High-Expanding Cortical Areas Preferentially Targeted?†", "Inhibition of SRGAP2 function by its human-specific paralogs induces neoteny during spine maturation", "The von Economo neurons in the frontoinsular and anterior cingulate cortex", "The role of the striatum in social behavior", Max Planck Institute for Evolutionary Anthropology, Max Planck Institute for Human Cognitive and Brain Sciences, Evolutionary psychology research groups and centers, Bibliography of evolution and human behavior, https://en.wikipedia.org/w/index.php?title=Evolution_of_human_intelligence&oldid=989247392, CS1 maint: BOT: original-url status unknown, Short description is different from Wikidata, Articles with unsourced statements from June 2009, Articles with unsourced statements from May 2017, Articles with unsourced statements from February 2015, Articles with unsourced statements from June 2011, Articles with unsourced statements from November 2019, Articles which contain graphical timelines, Creative Commons Attribution-ShareAlike License, This page was last edited on 17 November 2020, at 21:59. For example, if only individuals capable of remembering what they had agreed to were punished for breaking agreements, evolution would have selected against the ability to remember what one had agreed to. The human brain is a highly complex and central organ that is capable of performing a number of important functions like memory, intelligence, arousal, motivation, and hemostasis. , While decreased brain size has strong correlation with lower intelligence in humans, some modern humans have brain sizes as small as Homo Erectus but normal intelligence (based on IQ tests) for modern humans. But it turns out that cultural changes may be able to foster genetic changes that affect intelligence, while technological advances are ushering in a new era of brain evolution. 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. , Human brain evolution involves cellular, genetic, and circuitry changes. The group benefits of intelligence (including language, the ability to communicate between individuals, the ability to teach others, and other cooperative aspects) have apparent utility in increasing the survival potential of a group.  The cerebral cortex is divided into four lobes (frontal, parietal, occipital, and temporal) each with specific functions. Evolution of the Brain and Intelligence covers the general principles of behavior and brain function. Evolution of the Brain and Intelligence. These environmental pressures caused selection to favor bipedalism: walking on hind legs. is evident by 30,000 years ago. The eldest findings of Homo sapiens in Jebel Irhoud, Morocco date back ca. In In L. N. Trut and L. V. Osadschuk eds., Friedrich Nietzsche Beyond Good and Evil: Prelude to a Philosophy of the Future 1886. In fact, the size of a species' brain can be much better predicted by diet instead of measures of sociality as noted by the study conducted by DeCasien et al.  However, this hypothesis has been under academic scrutiny in recent years and has been largely disproven.  Studies show that the striatum plays a role in understanding reward and pair-bond formation. There are two main areas of the brain commonly associated with language, namely: Wernicke's area and Broca's area. The continuous process of creating, interacting, and adjusting to other individuals is a key component of many species' ecology. Brain and body size increase Intelligence: What Is It? 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).
2020 evolution of the brain and intelligence