evolution of the brain and intelligence
Download it once and read it on your Kindle device, PC, phones or tablets. Tamed foxes, for example, exhibit advanced forms of social communication (following pointing gestures), pedomorphic physical features (childlike faces, floppy ears) and even rudimentary forms of theory of mind (eye contact seeking, gaze following). While sexually selected ornaments such as peacock feathers and moose antlers develop either during or after puberty, timing their costs to a sexually mature age, human brains expend large amounts of nutrients building myelin and other brain mechanisms for efficient communication between the neurons early in life.  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 … A predominant model describing the evolution of human intelligence is ecological dominance-social competition (EDSC), explained by Mark V. Flinn, David C. Geary and Carol V. Ward based mainly on work by Richard D. Alexander.  Researchers attribute this result to the constraints on the evolutionary process of increasing brain size. 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. Thus, humans use social contracts to lay the benefits and losses each party will be receiving (if you accept benefit B from me, then you must satisfy my requirement R). "Foxes" pp. Given this situation, preference for smarter child-bearing/rearing partners increases the chance that their descendants will inherit the best resistance alleles, not only for immune system resistance to disease, but also smarter brains for learning skills in avoiding disease and selecting nutritious food. , Phylogenetic studies of brain sizes in primates show that while diet predicts primate brain size, sociality does not predict brain size when corrections are made for cases in which diet affects both brain size and sociality.  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. , Human brain evolution involves cellular, genetic, and circuitry changes. The response used by scientists to explain the evolution of the human brain involves a "fast evolution" scheme. Read reviews from world’s largest community for readers.  The human variant of the gene SRGAP2, SRGAP2C, enables greater dendritic spine density which fosters greater neural connections. As brain size expanded over the course of primate evolution, the number of neurons in the primate brain increased quickly, leading to big improvements in cognition. People infected with parasites may have brain damage and obvious maladaptive behavior in addition to visible signs of disease. Brain properties assumed to be relevant for intelligence are the (absolute or relative) size of the brain, cortex, prefrontal cortex and degree of encephalization. Article; Info & Metrics; eLetters; PDF; This is a PDF-only article. A big portion of the scholarly literature focus on the evolution, and subsequent influence, of culture. With their three times smaller brain the Flores hominids apparently used fire and made tools as sophisticated as those of their ancestor H.erectus. In rodents, however, the expansion of brain size led to only small increases in the number of neurons, with little or no improvement in cognitive ability. Use features like bookmarks, note taking and highlighting while reading Evolution of The Brain and Intelligence. 300,000 years  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. , Simian primate brain evolution studies show that specific cortical regions associated with high-level cognition have demonstrated the greatest expansion over primate brain evolution. The social brain hypothesis was proposed by British anthropologist Robin Dunbar, who argues that human intelligence did not evolve primarily as a means to solve ecological problems, but rather as a means of surviving and reproducing in large and complex social groups. . The brain is a very fascinating organ that weighs almost 2% of the total body mass of an individual. The introductory chapter covers the studies of animal behavior and their implications about the nature of the animal’s world. 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. One common characteristic that is present in species of "high degree intelligence" (i.e. Science 02 Aug 1974: Vol. An intelligence that, today, is highly variant from individual to individual. Evolution of the Brain and Intelligence by Harry J. Jerison With the agreement of author and publisher, Evolution of the Brain and Intelligence, by Harry J. Jerison (New York: Academic Press, 1973), was sent for review, along with a copy of the precis printed below, to a … 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. brain indices to address questions about the evolution of the brain and in telligence. 185, Issue 4149, pp. Some of the behaviors associated with living in large gr… American Psychological Association . Critical researchers argue the above shows that the cost of intelligence is a signal which reduces the chance of surviving to reproductive age, and does not signal fitness of sexually mature individuals. There has been a gradual increase in brain volume as humans progressed along the timeline of evolution (see Homininae), starting from about 600 cm3 in Homo habilis up to 1500 cm3 in Homo neanderthalensis. 211-214. Communicating across the subfields, the journal features papers in a wide variety of areas, including social, cultural, and physical anthropology as well as ethnology and ethnohistory, archaeology and prehistory, folklore, and linguistics. The evolution of human intelligence is closely tied to the evolution of the human brain and to the origin of language. Thus, widespread, virulent, and archaic infections are greatly involved in natural selection for cognitive abilities.  On a circuitry level, humans exhibit a more complex mirror neuron system, greater connection between the two major language processing areas (Wernicke's area and Broca's area), and a vocal control circuit that connects the motor cortex and brain stem. Both intelligence (in the IQ test sense) and creativity appear to be the products of widely distributed functional networks in the brain, which are at least partly independent of one another. These concepts can be tied to the social brain hypothesis, mentioned above. This is because it paid to be a highly variable male, as average males would have consistently low opportunity, but variable males had a chance of falling on the preferred side of the trait distribution. An icon used to represent a menu that can be toggled by interacting with this icon. Here they were exposed to predators, such as the big cats, from whom they had previously been safe. 185, Issue 4149, pp. Theref… Useful brain indices have been proposed [e.g., Jerison, 1973, 1977; Passingham, 1975; Riddell and Corl, 1977], but behavioral meas ures currently in use are too limited or have questionable validity as in dices of intelligence. Chimpanzees live in groups of about 50 individuals whereas humans typically have a social circle of about 150 people, which is also the typical size of social communities in small societies and personal social networks; this number is now referred to as Dunbar's number. Hence, tamed foxes show a reduced adrenal gland size and have an up to fivefold reduction in both basal and stress-induced blood cortisol levels. By Stephen Jay Gould. , Another theory that tries to explain the growth of human intelligence is the reduced aggression theory (aka self-domestication theory). 200,000 year old fossils of Homo sapiens were found in East Africa. Scholars suggest that this could have, in part, been caused by convergent evolution. Brain size increases slowly. 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. This is in part because the leaps human intelligence has taken are far greater than those that would have resulted if our ancestors had simply responded to their environments, inhabiting them as hunter-gatherers. (1990).  As a result, humans became even more dependent on tool-making to compete with other animals and other humans, and relied less on body size and strength. 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). 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