290 Textbook chapter 2

17 Pages
Unlock Document

University of Toronto Mississauga
Amanda( Mandy) Wintink

290 Textbook Notes [Lecture 2] Chapter 2: Evolution 1 T HINKING A BOUT THE B IOLOGY OF B EHAVIOUR 1.1 IS ITP HYSIOLOGICAL OR PSYCHOLOGICAL ? I. Modern science born out of Renaissance scholars who were not content to follow the dictates of the church – started to study things by directly observing them II. Rene Descartes a. 17 century French philosopher b. Argued that the universe is composed of 2 elements i. Physical matter: behaves according to the law of nature and therefore is a suitable object of scientific investigation ii. The mind/soul: lacks physical substance, controls human behaviour, obeys no natural laws, therefore is the appropriate purview of the Church c. Cartesian dualism i. Term for Descarte’s philosophy ii. Sanctioned by the Roman Church – idea that mind and body are separate became even more widespread 1.2 IS ITINHERITED OR S ITL EARNED ? I. Nature-nurture issue II. Most psychologists supported the nurture side a. Ex. behaviourist John B. Watson III. Experimental psychology in North America a. Root in ethology (study of animal behaviour in the wild) b. Became the dominant approach to study of behav in Europe c. Focused on instinctive behaviours (behav that occurs in all members of a species) d. Emphasized role of nature 1.3 P ROBLEMS WITH T HINKING ABOUT THE BIOLOGY OF B EHAVIOUR IN TERMS OF TRADITIONAL D ICHOTOMIES 1.3.1 Physiological-or-Psychological Thinking Runs Into Difficulty I. Descarte’s philosophy came under attack after being sanctioned II. physio-or-psych thinking a. assumption that some aspects of human psychological functioning are so complex that they could not possibly be the product of the human brain b. 2 lines of evidence against it: i. Demonstrations that even the most complex psychological changes (ex. changes in memory, emotion) can be produced by damage to, or stimulation of, parts of the brain ii. Demonstrations that some nonhuman species (particularly primates) possess abilities that were once assumed to be purely psychological and therefore purely human 1.3.2 Nature-or-Nurture Thinking Runs Into Difficulty I. ‘how much of this is genetic and how much is experience’ a. Fundamentally flawed thinking b. Based on the premise that genetic factors and experiential factors combine in an additive fashion c. Ex. that intelligence is a result of the mixture of so many parts of genetics and so many parts of experience, rather than through the interaction of them II. Experience continuously modifies genetic expression 1.3.3 A Model of the Biology of Behaviour I. All behaviour is the product of interaction between three factors a. Organism’s genetic environment (a product of its evolution) b. Its experience c. Its perception of the current situation 2 H UMAN E VOLUTION I. Modern biology began in 1859 with the publication of Darwin’s On the Origin of Species a. Darwin wasn’t the first to suggest that species evolve (undergo gradual orderly change) from pre-existing species, but was the first to amass a large body of supporting evidence II. Presented 3 kinds of evidence to support his theory a. Documented the evolution of fossil records through progressively more recent geological layers b. Described striking structural similarities among living species (ex. a human’s hand and bird’s wing) which suggested they evolved from common ancestors c. Pointed to major changes that had been brought about in domestic plants and animals by programs of selective breeding III. directly observed rapid evolution in progress, ex. finches of the Galapagos Islands IV. argued that evolution occurs through natural selection a. heritable traits associated with high rates of survival and reproduction are the most likely to be passed onto future generations b. when natsel is repeated for generations, it leads to the evolution of species better adapted to surviving and reproducing in their particular environments V. fitness: ability of an organism to survive and contribute its genes to the next generation 2.1 E VOLUTION AND B EHAVIOUR 2.1.1 Social Dominance I. Males of many species establish a stable hierarchy of social dominance through combative encounters with other males a. In some species, there is physical damage b. In other species, there is mainly posturing and threatening until one combatant breaks down II. Once a hierarchy is established, hostilities diminish a. Lower ranking males learn to avoid or submit to the dominant males III. Why is it important in evolution? a. Dominant males copulate more than non-dominant males – more effective at passing on genes b. In some species, dominant females are more likely to produce more, and healthier, offspring 2.2 C OURSE OF H UMAN E VOLUTION 2.2.1 Evolution of Vertebrates I. 600 MYA a. Complex, multi-cellular, water-dwelling organisms first appeared on earth II. 450 MYA a. First chordates evolved i. Animals with dorsal nerve cords b. First chordates w/ spinal bones to protect their cords evolved 25 million years later c. Chordates that possess them are called vertebrates d. First vertebrates were primitive bony fishes 2.2.2 Evolution of Amphibians I. 410 MYA a. First bony fishes ventured out onto land b. Those that could survive briefly had 2 advantages: i. Could escape from stagnant pools to nearby fresh water ii. Could take advantage of terrestrial food sources II. Natsel transformed the fins and gills of fishes to legs and lungs a. First amphibians evolved 400 MYA b. Ex. frogs, salamanders 2.2.3 Evolution of Reptiles I. 300 MYA II. Reptiles evolved from a branch of amphibians III. First vertebrates to lay shell covered eggs and be covered in dry scales a. These adaptations reduced reliance of replies on watery habitats IV. Ex. lizards, snakes, turtles 2.2.4 Evolution of Mammals I. 180 MYA during the height of the age of dinosaurs a. New class of vertebrates evolved from a line of small reptiles b. Females fed young with secretions from special glands called mammary glands c. Eventually, stopped laying eggs and females nurtured young in their bodies until the young were mature enough to be born i. Duck billed platypus – remaining mammalian species that still lays eggs II. Spending first year inside mother’s body – survival advantages a. Long-term security b. Environmental stability for development to unfold III. We belong to the order primates a. Particularly dif to categorize b/c there’s no single characteristic that is possessed by all primates but no other animals b. Apes i. thought to have evolved from a line of Old-World monkeys ii. long arms and grasping hind feet specialized for arboreal (treetop) travel iii. opposable thumbs not long enough to be of precise use iv. no tails, can walk upright for short distances v. chimpanzees – closest living relatives of humans (99% genes identical) 2.2.5 Emergence of Humankind I. Primates of the family that includes humans are the hominins a. Family composed of 2 genera (plural of genus) i. Australopithecus ii. Homo 1. Thought to be composed of 2 species: a. Homo erectus (extinct) b. Homo sapiens (humans) II. Little information exists III. Most believe that the australopithecines evolved about 6 million years ago in Africa from a line of apes IV. First Homo species are thought to have evolved from one species of Australopithecus about 2 MYA a. Had large brain cavity, early Homo used fire and tools V. About 50,000 years ago, modern humans began migrating out of Africa VI. 3 human attributes: a. Large brain b. Upright posture c. Free hands with opposable thumbs 2.2.6 Thinking about Human Evolution I. Evolution does not proceed down a single line a. More of a dense bunch II. Evolution does not always proceed slowly and gradually a. Rapid evolutionary changes can be triggered by sudden changes in the environment or by adaptive genetic mutations III. Not all existing behaviours or structures are adaptive a. Evolution often occurs through changes in developmental programs that lead to several related characteristics, only one of which might be adaptive b. Incidental, non-adaptive evolutionary by-products are called spandrels c. Ex. human belly button – serves no adaptive function, merely a by-product of the umbilical cord IV. Not all existing adaptive characteristics evolved to perform their current function a. Some, called exaptations, evolved to perform one function and were later co-opted to perform another b. Ex. bird wings are limbs that first evolved for the purpose of walking V. Similarities among species don’t necessarily mean that the species have common evolutionary origins a. Similar structures due to common evolutionary origin = homologous b. Similar structures with no common origin = analogous c. Similarities b/w analogous structures result from convergent evolution i. Evolution of unrelated species of similar solutions to the same environmental demands 2.3 E VOLUTION OF THE H UMAN B RAIN I. Early research focused on size a. Stimulated by belief that brain size and intellectual capacity are closely related b. Problems: i. Modern humans, believed to be most intelligent, don’t have the biggest brains (whales and elephants do) ii. Sizes of brains of acclaimed intellectuals (ex. Einstein) were found to be unremarkable c. There is no clear relationship b/w overall human brain size and intelligence II. Bigger animals require more tissue to control and regulate them a. Therefore large men tend to have bigger brains, and men tend to have bigger brains than women b. Brain weight expressed as percentage of total body might be a better measure but the shrew would surpass humans in that case III. More reasonable approach – compare the evolution of dif brain regions a. Consider evolution of brain stem separate from cerebrum (cerebral hemispheres) i. Brain stem regulates reflex activities critical for survival (heart rate, respiration) ii. Cerebrum is involved in more complex adaptive processes (learning, perception) IV. 3 important points about the evolution of the human brain: a. It has increased in size during evolution b. Most of the increase has occurred in the cerebrum c. An increase in number of convulsions (folds on cerebral surface) has greatly increased the volume of the cerebral cortex (outermost layer of cerebral tissue) 2.4 T HINKING A BOUT E VOLUTIONARY P SYCHOLOGY I. Good theories about evolution have predictions about current behavs built into them so the they can be tested II. Theory of mate bonding has led to several predictions about current aspects of human male selection III. Confirmed predictions: a. Men in most cultures value youth and attractiveness (indicators of fertility) more than women do, women value power and earning capacity b. Physical attractiveness best predicts which women will bond with men of high occupational status c. Men are more likely to commit adultery 3 F UNDAMENTAL G ENETICS 3.1 M ENDELIAN G ENETICS I. Mendel, an Austrian monk, studied inheritance in pea plants II. Studied dichotomous traits a. Traits that occur in one form or the other, never in combination (ex. either brown or white seeds) III. Began experiments by crossing the offspring of true-breeding lines a. Breeding lines in which interbred members always produce offspring with the same trait (ex. brown seeds) generation after generation IV. Studied the inheritance of seed color (brown or white) a. Began by cross breeding offspring of a line of pea plants that bred true for brown seeds with the offspring of a pea plant that bred true for white seeds b. Bred first generation offspring with one another nd i. Found that ¾ of resulting 2 generation plants had brown seeds and ¼ had white seeds ii. Repeated experiment and result was the same each time c. One trait was dominant and appeared in all first generation offspring d. The other trait was recessive and appeared in about ¼ of the 2 generation plants V. Results of his experiments challenged central premise on which all previous ideas about inheritance had rested (that offspring inherit the traits of their parents) a. Somehow, recessive white seed trait was passed down to ¼ of 2 generation pea plants by first generation plants that didn’t possess it VI. Phenotype: organism’s observable traits VII. Genotype: genetic material VIII. Mendel devised a theory to explain his results that comprised 4 ideals a. There are two kinds of inherited factors for each dichotomous trait i. Ex. a brown seed factor and a white seed factor control for seed color ii. Now call each inherited factor a gene b. Each organism possesses two genes for each of its dichotomous traits i. Ex. each pea plant possesses either two brain seed genes, two white seed genes, or one of each ii. The two genes that control the same trait are called alleles iii. Homozygous – possess two identical genes for a trait iv. Heterozygous – possess two different genes for a trait c. One of the two kinds of genes for each dichotomous trait dominates the other in heterozygous organisms d. For each dichotomous trait, each organism randomly inherits one of its ‘father’s two factors and one of its ‘mother’s’ two factors 3.2 C HROMOSOMES : R EPRODUCTION AND R ECOMBINATION I. It was not until the 20 century that genes were found to be located on chromosomes (threadlike structures in the nucleus of each cell) a. Occur in matched pairs and each species has a characteristic number of pairs in each of its body cells (humans have 23) b. The two genes (alleles) that control each trait are situated at the same location, one on each chromosome of a particular pair II. Process of cell division that produces gametes (egg cells and sperm cells) is called meiosis a. Chromosomes divide and one chromosome of each pair goes to each of the two gametes that results from the cell division b. As a result, each gamete has only half of the usual number of chromosomes (23 in humans) c. When a sperm cell and an egg cell combine during fertilization, a zygote (a fertilized egg cell) with the full complement of chromosomes is produced III. The random division of the pairs of chromosomes into two gametes is not the only way meiosis contributes to genetic diversity a. During the first stage of meiosis, the chromosomes line up in their pairs b. The members of each pair cross over one another at random points, break apart at the points of contact, and exchange sections of themselves c. As a result of this genetic recombination, each of the gametes that formed the zygote contained chromosomes that were unique IV. In contrast, all other cell division in the body occurs by mitosis a. Just prior to division, the number of chromosomes doubles so that when the cell divides, both daughter cells end up with the full complement of chromosomes 3.3 C HROMOSOMES : S TRUCTURE AND R EPLICATION I. Each chromosome is a double-stranded molecule of deoxyribonucleic acid (DNA) II. Each strand is a sequence of nucleotide bases attached to a chain of phosphate and deoxyribose a. There are 4 nucleotide bases: i. Adenine ii. Thymine iii. Guanine iv. Cytosine b. It’s the sequence of these bases on each chromosome that constitutes the genetic code III. The two strands that compose each chromosome are coiled around each other and bonded together by the attraction of adenine for th
More Less

Related notes for PSY290H5

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.