Research Paper

Research Paper - Evidence that natural selection is still...

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In establishing that positive selection is still operating on human intelligence, the nature and measurability of intelligence must first be examined. A primary characteristic of human intelligence is flexibility. While most animals are specialists (i.e. bees are proficient at communicating through their Waggle dances, beavers are adept at building dams), humans have the ability to imitate many different kinds of skills (1). Studies have shown that chimpanzees are also capable of simulating motor acts, which demonstrates a preexisting capacity for the final development that appears solely in humans. While chimpanzees can represent what they perceive, humans can represent what they imagine: humans’ ability to recombine mental elements led to developments such as science and art. For example, Galileo’s world without friction, where objects set in motion remain in motion, is not a perceived world, but an imagined one (1). In addition, magnetic resonance imaging (MRI) and external head size measures show that brain size is related to IQ (2); thus, the evolutionary expansion of the human brain is believed to be important to advances in human intelligence such the emergence of language. Microcephalin and ASPM are two genes that regulate brain size and experienced strong positive selection in the ape lineage leading to humans . Their impact on brain size has been demonstrated by the fact that people carrying a non-functioning mutant copy of these genes suffer from microcephaly, a Evidence that natural selection is still operating on human intelligence Melissa Harintho BIOS 10162- Belovsky The defining process in the evolution of primates and especially humans is the expansion of the brain. While many types of genes could potentially contribute to this process, genes that specifically regulate brain size during development are particularly relevant. The ongoing evolution of such genes, as well as the dissimilar evolutionary patterns of intelligence across different racial and cultural groups indicates that natural selection is still operating on human intelligence.
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congenital defect characterized by mental retardation and a normally structured brain that is approximately 70% smaller than usual. In 2003, geneticist Andrew P. Jackson examined the role of Microcephalin in primary microcephaly. In the developing cerebral cortex of the fetal brain, Microcephalin is specifically expressed in the control of the proliferation and/ or differentiation of neuroblasts during neurogenesis. As a result, primary microcephaly is the autosomal recessive neurodevelopmental condition in which there is an overall reduction in cerebral cortex volume comparable to that of early hominids. This correlation leads to the compelling implication that Microcephalin evolved under strong positive selection in the primate lineage leading to Homo sapiens (3) .
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Research Paper - Evidence that natural selection is still...

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