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Lecture 1 Lecture 1 Document Transcript

  • PSYC 3102: Introduction to Behavioral Genetics Lecture 1 History of Genetics —Provides framework of where we are and where we’re going Mankind has had implicit knowledge of genetics for a long time, but had no “hard science” or explicit knowledge - the first genetic engineering began 10-20,000 years ago in the form of breeding plants and animals for desired traits - wild onions, lentils, and ginger were engineered by humans, and replaced the original progenitor plants First known attempt to explain heredity—Hippocrates Hippocrates’ theories:  Bricks & mortar approach—thought sperm contained tiny body parts and transferred them to ‘fertile ground’ of womb where the parts assembled and grew  Believed in the inheritance of acquired characteristics—characteristics which parents acquire prior to conception are past on to offspring  Example: strong Olympic body builders pass on big biceps so their offspring are born strong Olympic body builders  Example: giraffes that stretched their necks to reach leaves had offspring with longer necks Aristotle:  Generation or two after Hippocrates  Criticized Hippocrates’ theories:  On ‘bricks and mortar’ approach  Mutilated parents can have normal children  Example: father loses arm in war, but offspring has two arms  On inheritance of acquired characteristics  Parents can transmit traits they do not show at the time of conception  Example: gray hair – offspring can go gray even though parents had dark hair when offspring were conceived  Aristotles’ Theory:  What is inherited is information  Building a house analogy—one inherits the blueprint of how to make the house, not the actual bricks and mortar  But was ignored, most people went with the bricks and mortar theory
  • Foundation of Modern Genetics -- Science doesn’t develop in a vacuum, background and context is important The 3 L’s: -- Science tends to fit into a certain world view (bias, theoretical framework), and the views of the 3 L’s created the world view/theoretical framework in which modern genetics began to develop 1. Linnaeus (~1700) Developed classification system Classification was:  Heirarchical – implies species are related, genus - species concept  Based on external morphology – similar looking = closely related  Based on belief that species are fixed and immutable – creationist view/no evolution 2. Lamark (~1800) First modern evolutionist  Challenged belief of species being fixed and immutable  Believed that species change over time in response to environmental demand  But, believed (falsely) in the inheritance of acquired characteristics theory 3. Lyell (~1830) founder of modern geology  Challenged Creationism theory—the earth is far older than the bible says (millions of years rather than thousands of years old)  Earth as we know it is the result of physical changes occurring over long periods of time, features have changed due to ice ages, erosion, etc.  Darwin took Lyell’s book with him on the Beagle
  • Birth of Modern Genetics -- Darwin, Mendel, Modern Cell Biology Darwinian Trend  Started out to become a physician, but couldn’t handle the sight of blood  So, Darwin became naturalist on the Beagle (sailed for 5 years) in 1830’s  Keep in mind the context of the time—Linnaeus (species are related); Lamark (species evolve); and Lyell (earth is millions of years old and has changed throughout time)  Darwin’s theory:  Those animals best adapted to their environment are more likely to reproduce than those less adapted to the environment  Studied finches, similar but different from island to island  Type of beak vs. food available (insects vs. seeds/nuts)  Returned to England and obsessively, compulsively wrote for many years (want all information and details to be perfect)  Social circle included many top scientists at the time  Push to publish…  Alfred Wallace independently came up with the same theory  Wallace went to Royal Society, but got pushed into background so Darwin could publish first  1859 – published “Origin of Species”  Was a bestseller, sold out first edition before printed  The theory enflamed the discord between physical geologists and biblical creationists  Genesis has two accounts of creation  Creationists criticize—“Humans have evolved? No way”  Side note: We are NOT descended from apes and chimpanzees, we share common ancestors (cousins of sorts)  Problems—Darwin’s book is internally inconsistent, he provides no theory of inheritance!  There MUST be variability  He believed in “blending” inheritance (offspring is blended of both parents)  But with this theory, all variability would be lost after several generations (mixing watercolors analogy)  So, fudged theory, and supported theory of acquired characteristics, claimed that this provided the necessary variability  An unopened reprint from Mendel was found in his desk after his death, this was the theory of inheritance that he need to incorporate
  •  Darwin also wrote the 1st evolutionary Psychology book  Dealt with human and animal behavior  Expression of emotion  Facial expressions (blind children smile, not merely mimicking behavior) Darwinian follower (and cousin) Francis Galton  1st to establish psych lab that measured individual differences  1st to propose the twin method  1st to come up with regression theory (and draw a regression line)  Coined term “Eugenics” (started movement in England)  1st to do empirical work on behavioral genetics  published book “Hereditary Genius” (1960s)  Looked at “eminent” people in society (top in politics, arts, science)  Then traced their family histories  1st degree relatives (fathers, brothers, & sons); 20% are also eminent in society  2nd degree relatives (grandfathers, uncles & ½ brothers); 8% are eminent  3rd degree relatives (male cousins); 2-3% eminent in society  percent of relatives that are eminent in society increases with the degree of relatedness  “Genius must be inherited”  Main criticism: (VERY IMPORTANT – WILL SEE ON TEST) ∗ Shared family resemblence can not distinguish the role of genes from that of the environment ∗ Familial resemblance is a function of shared genes, shared environment, and some combination of shared genes and shared environment ∗ Family studies cannot elucidate the influence of genes from that of the environment • Twin and adoption studies are needed to distinguish the effects of shared genes and the effects of shared environment Examples of essay questions Beware of statements such as “it runs in families, therefore…” Remember this cannot be determined with family studies!!! Ex: Fears and Phobias Environmental: Watson, social Ex: Abuse learning Environmental: social learning, Genetic: inherited traits of Genetic: inherited traits such as anxiety, fear aggression, etc.
  • Social Darwinism and Eugenics  Eugenics—“well” “genetics”; better people through better breeding  Positive push: provide benefits to and encourage ‘desirable’ people to breed  Negative push: discourage ‘undesirable’ people to breed  Social Darwinism—application of Darwin’s principles to society at large  The seeds of this were established before Darwin ever published  Victorian Era England used this to justify colonialism by their politicians  Herbert Spencer (NOT DARWIN) coined the phrase “Survival of the Fittest”