Without sexual selection, an unattractive individual might find a superior mate with few deleterious mutations, and have healthy children that are likely to survive. 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).  Studies have demonstrated the presence of the mirror neuron system in both macaques in humans; However, the mirror neuron system is only activated in macaques when observing transitive movements.. Evolution of the Brain and Intelligence covers the general principles of behavior and brain function. Gould, E. (2007). In addition, there is evidence to suggest that the success of groups is dependent on their size at foundation, with groupings of around 150 being particularly successful, potentially reflecting the fact that communities of this size strike a balance between the minimum size of effective functionality and the maximum size for creating a sense of commitment to the community. , In many species, only males have impressive secondary sexual characteristics such as ornaments and show-off behavior, but sexual selection is also thought to be able to act on females as well in at least partially monogamous species. "Against 'Sociobiology'". Allen, Elizabeth, et al. This adaptation enabled the human brain to continue to grow, but it imposed a new discipline. Download it once and read it on your Kindle device, PC, phones or tablets. A big portion of the scholarly literature focus on the evolution, and subsequent influence, of culture. The final third of our evolution saw nearly all the action in brain size. An intelligence that, today, is highly variant from individual to individual. "Effects of domestication on the adrenal cortisol production of silver foxes during embryonic development ". Not only do humans need to determine that the contract was violated, but also if the violation was intentionally done. Around 10 million years ago, the Earth's climate entered a cooler and drier phase, which led eventually to the Quaternary glaciation beginning some 2.6 million years ago. Thus, widespread, virulent, and archaic infections are greatly involved in natural selection for cognitive abilities. JSTOR is part of ITHAKA, a not-for-profit organization helping the academic community use digital technologies to preserve the scholarly record and to advance research and teaching in sustainable ways. A larger brain requires a larger skull, and thus requires the female to have a wider birth canal for the newborn's larger skull to pass through.  Researchers attribute this result to the constraints on the evolutionary process of increasing brain size. These critics argue that human intelligence evolved by natural selection citing that unlike sexual selection, natural selection have produced many traits that cost the most nutrients before puberty including immune systems and accumulation and modification for increased toxicity of poisons in the body as a protective measure against predators..  Thus the direct adaptive benefit of human intelligence is questionable at least in modern societies, while it is difficult to study in prehistoric societies. 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. Smarter people can more skillfully learn to distinguish safe non-polluted water and food from unsafe kinds and learn to distinguish mosquito infested areas from safe areas. Access supplemental materials and multimedia. An icon used to represent a menu that can be toggled by interacting with this icon. "Foxes" pp. The first 3 million years of this timeline concern Sahelanthropus, the following 2 million concern Australopithecus and the final 2 million span the history of the genus Homo in the Paleolithic era. The reality of encephalization--the relatively large human brain--with its correspondingly high intelligence, is readily apparent.The object of current research and debate, however, is the examination of what evolutionary factors have driven the development of increased human encephalization.  Researchers have attributed hominin evolution to mosaic evolution. How widespread is adult neurogenesis in mammals? de Waal, Frans B. M. (1989). This means that less attractive individuals will find other less attractive individuals to mate with. All Rights Reserved. Homologous regions have been found in other species (i.e. CS1 maint: multiple names: authors list (, How the body shapes the way we think: A new view of intelligence, Rolf Pfeifer, Josh Bongard, Eccles, John C. (1989).  It seems as though the neoteny of domesticated animals significantly prolongs the immaturity of their hypothalamic-pituitary-adrenal system (which is otherwise only immature for a short period when they are pups/kittens) and this opens up a larger "socialization window" during which they can learn to interact with their caretakers in a more relaxed way. 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. 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.. It is unclear to what extent these early modern humans had developed language, music, religion, etc. Human intelligence is developed to an extreme level that is not necessarily adaptive in an evolutionary sense. The brain is a very fascinating organ that weighs almost 2% of the total body mass of an individual. The human brain is an important structure that has the largest size when compared to other vertebrates relative to the size of the organism.
2020 evolution of the brain and intelligence