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Chapter 2

Chapter 2.docx

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PSYC 271
Monica Valsangkar- Smyth

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Chapter 2 Evolution, Genetics, and Experience- Thinking about the Biology of Behaviour - Zeitgeist- the general intellectual climate of our culture - Cartesian dualism- the philosophical position of Rene Descartes, who argued that the universe if composed of two elements: physical matter and the human mind o The idea that the human brain and the mind are separate entities became even more widely accepted - Nature-nurture issue is a very dichotomic way of thinking - John B. Watson believed that nurture made had the biggest effect- father of behaviourism - Zeitgeist- general intellectual climate of our culture - Ethology- the study of animal behaviour in the wild - Instinctive behaviours- Behaviours that occur in all like members of a species even when there seems to have been no opportunity for them to have been learned - Two lines of evidence against physiological-or-psychological thinking: o First line is composed of the many demonstrations that even the most complex psychological changes (e.g changes in self-awareness, memory or emotion) can be produced by damage to or stimulation of parts of the brain o Second line of evidence is composed of demonstrations that some nonhuman species, particularly primate species, posses abilities that were once assumed to be purely psychological and thus purely human - Self-awareness is widely regarded as one of the hallmarks of the human mind - Asomatognosia- a deficiency in the awareness of parts of one’s own body o Usually results from damage to the right parietal lobe; involves the left side of the body - Neurons become active long before they are fully developed, (2) the subsequent course of their development (e.g. the number of connections they form or whether or not they survive) depends greatly on their activity, much of which is triggered by external experience, (3) experience continuously modifies genetic expression - Model of biology of behaviour premise is that all behaviour is the product of interactions among three factors: o 1. The organisms genetic endowment, which is the product of its evolution o 2. Its experience o 3. Its perception of the current situation - Darwin and evolutions: evidence to support evolution o 1. Evolution of fossil records through progressively more recent geological layers o 2. Striking structural similarities among living species—suggested they evolved from common ancestors o 3. Major changes that had been brought about in domestic plans and animals by programs of selective breeding o 4. Observations of rapid evolution in progress - Darwin argued that evolution occurs through natural selection o Natural selection leads to evolution - Fitness is the ability to survive and contribute its genes to the next generation - Males of many species establish a stable hierarchy of social dominance through combative encounters with other males - Males lower in the hierarchy tend to fight less - Social dominance is an important way to pass genes on - High ranking females produce better offspring - Intricate series of courtship displays precedes copulation in many species - Copulation is unlikely to occur if one of the pair fails to react appropriately to the signals of the other - Species- a group of organisms that is reproductively isolated from other organisms - New species begins to branch off from an existing species when a barrier discourages breeding between a subpopulation of the existing species and the remaining species - Reproductive barrier may be geographic or behavioural (display a different kind of behaviour that separates them) - Conspecifics- members of the same species - Chordates- animals with dorsal nerve cords (large nerves that run along the center of the back or dorsum) - Vertebrates- Chordates that posses spinal bones called vertebrae - First vertebrates were primitive bony fish - Seven classes of vertebrates: three classes of fishes, amphibians, reptiles, birds and mammals - The first amphibians evolved about 400 million years ago from bony fish - Only adult amphibians can survive on land - Reptiles were first vertebrates to lay shell-covered eggs and be covered by dry scales - Mammals are named after the mammary glands through which they feed their young - Mammals nurture their young in the watery environment of their bodies until they are ready to be born o Platypus is the only mammal that lays eggs - Most classification systems recognize about 20 different orders of mammals - Humans belong to the order primates; there are about a dozen primates - Apes are thought to have evolved from a line of old-world monkeys - Chimpanzees are the closest living relatives of humans; almost 99% of genes are identical in the two species - Hominins- primates of the family that include humans - Family is composed of two genera: Australopithecus and homo - Homo is thought to be composed of two species: Homo erectus (extinct) and Homo Sapiens (humans) - First homo species are thought to have evolved from one species of Australopithecus about 2 million years ago - Distinctive feature of the early homo species was the large size of their brain cavity; larger than that of Australopithecus but smaller than that of modern humans - Spandrels- the incidental non-adaptive evolutionary bi-products; ex. The belly button - Exaptations- evolved to perform one function and were later co-opted to perform another; ex. Wings - Homologous- structures that are similar because they have a common evolutionary origin - Analogous- structures that are similar but do not have a common evolutionary origin - Convergent evolution- the evolution in unrelated species of similar solutions to the same environmental demands - There is no clear relationship between brain size and intelligence o Whales and elephants have bigger brains than humans o Also acclaimed intellectuals have average sized brains - Larger bodies require more brain tissue to control and regulate them - More reasonable approach to the study of the brains evolution has been to compare the evolution of different brain regions - Brain stem evolution- regulates reflex activities that are critical for survival (heart rate, respiration, and blood glucose level) - Cerebrum (cerebral hemisphere) is involved in more complex adaptive processes such as learning, perception, and motivation - Three important points about the evolution of the human brain: o It has increased in size during evolution o Most of the increase in size has occurred in the cerebrum o An increase in the number of convolutions—folds on the cerebral surface- has greatly increased the volume of the cerebral cortex - All brains are constructed of neurons, and the neural structures in the brain of one species can usually be found in the brains of related species - Similar structures tend to perform similar functions - Human abilities appear to result from the modification of abilities found in our closest evolutionary relatives - In most species mating is promiscuous - Most mammals tend to form mating bonds o This may be due to the fact that mammals give birth to small numbers of offspring that need care and nurture. Adaptive
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