Understanding Brain Development & Adaptation: Evolutionary & Genetic Basis of Behavior, Lecture notes of Neurological Basis of Behavior

Download Understanding Brain Development & Adaptation: Evolutionary & Genetic Basis of Behavior and more Lecture notes Neurological Basis of Behavior in PDF only on Docsity! Neurological Basis of Behavior (PSY610) VU Lesson 06 EVOLUTIONARY AND GENETIC BASIS OF BEHAVIOUR Objective: To understand • The Brain behavior relationships from the perspectives of biological systems. • The concepts of theory of evolution and its developmental process. • Evolution of the homosapien and to understand brain development and behavior changes. Evolution: As we have seen in the last lesson, the concepts of evolution were also evolving, Darwin has built on what was already being thought about, but what makes his theory unique is what we are going to talk about today Theory of Evolution: Darwin was the first one who actually gave the mechanism of how or why the process of evolution takes place. The first premise being that there are limited resources and all living organisms compete for the limited resources available. Therefore a struggle for existence is essentially a struggle for resources and a struggle for survival. Who wins the battle? Clearly the species which has even slightest advantage, (long neck for giraffes if food higher up in the trees), will have the best chances for survival, and can continue to propagate under hostile and competitive conditions. The best adapters are therefore the best reproducers and the best reproducers are the ones best fit for survival. Decent With Modification: Variation in genetic population provides a rough template for natural selection to work on (the variation can also occur via mutation: change in chromosomal order or genetic code). Modification of genetic variation takes place through natural selection. What is Natural selection? Natural selection affects all living organisms, in keeping a species strong and fit for existence under the conditions in which it is living. NATURE SELECTS! Natural selection pressure s can work only in the presence of genetic variability Adaptations made in one generation, if beneficial would be carried on to the next generation there is constant process of adaptation. If species do not adapt they do not survive (dogs which do not learn to watch for cars on the road, die–which means the end of their genes). Primates developed extensions to help in survival/hunting (young chimps use hollow sticks for ants), as they could not compete with the stronger hunters and predators. Genetic Variation: ©Copyright Virtual University of Pakistan 21 docsity.com Neurological Basis of Behavior (PSY610) VU What is Genetic variation or phylogenetic inertia, these can be defined as basic inherited properties in which there is a variation and can be changed and the extent they can. All organisms have combinations of characteristics; however each has a unique combination. These combinations can change. Changes in the genetic combination can occur through a) combinations of different gene pools i.e. interracial marriage or marriage of completely unrelated individuals b) mutations; these are changes in the gene material through radiation or a genetic accident (or now genetic manipulation). These changes would lead to a new and unusual combination of genes. Survival of the fittest: qualities which enable survival and further propagation in a hostile environment. We are not talking of being healthy or physically strong but having qualities with which animals can propagate successfully and offspring survive to continue to contribute to gene pool. The gene pool for the next generation is better as weaker genes do not survive to contribute to gene pool. The fittest genes live on, propagate and make up the upcoming successive generations. What if we have a species doing very well, this would increase the number of surviving animals. This would again lead to competition for food thereby struggle for existence would continue Evolutionary adaptation and speciation: these are also evolutionary processes/ changes which a species goes through to enhance its survival. Evolutionary adaptation: there are two kinds of adaptations which can take place during the process of evolution, 1) Centripetal: which means the organism would remain in the same state, for millions of years as there are no environmental pressures to change. There is stability, and no change is beneficial for survival. The animal does not change e.g. silver fish is the same for millions of years. 2) Centrifugal: when there is a non stable environment with very rapid changes taking places, therefore rapid change in the species occurs to survive. It is during centrifugal change that mutations occur in large numbers and very rapidly as the selection pressures are intense. Speciation: when the same species spread to different geographical locations, they evolve differently into different species. The same birds in the sea would develop qualities of sea- birds, those which go up into the hills would develop characteristics needed for survival in the hills. Isolation: whenever a species was geographically isolated and there was no competition, theses would evolve into different species depending on the locations (divide territory for mutual benefit).The animals in Australia, and Galapagos are good examples. Adaptive radiation: adaptive process where the same species develops different characteristics. In Australia the marsupials radiated into different species such as tasmanian cat, koala (trees), duckbill (water), kangaroo (land) spreading and foraging across grass, tree, water, hill, land), Evolution: Mammalian, Primate To Homosapien: The first major phase in evolution is speculated to be when fishes move on to land, they evolved into amphibians dinosaurs. The dinosaurs ruled earth in various forms they were huge, physically but had very small brains. At about the end of reptilian era a very small mammalian species evolved: a) it had a fur coating for thermoregulation b) had strong olfaction (brain grew-due to olfaction?) c) better hearing (had to compete with large animals so had to forage in the dark)-bones in jaws moved to side to form ear bones, d) Vision gradually highly evolved for higher primates. ©Copyright Virtual University of Pakistan 22 docsity.com