Chapter 3

• Charles Darwin


  1809, England, tried medicine and theology but stopped, then pursued natural history
• HMS Beagle voyage


  1. Purpose: map shorelines of land areas around the world

  2. Opportunity to explore different species of plants and animals to understand the origin of the species

  3. Brought the book "Principles of Geology" by Charles Lyell
• Charles Lyell


  Considered the "Father of Geology", argued the Earth had been around for million years and changed slowly, so there was no reason to think that vast variety of life forms appeared overnight in their current form
• Animal breeding


  Deliberate model of changes "intervention by breeder"
• Thomas Malthus


  Argued population =/= utopia, but population = ruins, because of limited resources < increase of population, "nature is the breeder"
• Darwin: 'Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, will tend to the preservation of that individual, and will generally be inherited by its offspring. The offspring, also, will thus have a better chance of surviving.'
• Natural Selection


  Helps species adapt to change over generations, changes not just physical change but also certain kinds of behaviour as well, helps organisms adapt to change, not the individual
• The laws of governing inheritance are quite unknown
• Gregor Mendel


  Father of Genetics, characteristics are passed through genes
• If all members of species were genetically identical, natural selection is impossible because it depends on profitable variations
• Natural selection


  Does not demand perfection but survival
• Adaptations that served a species for thousands of years or even millions can become useless almost overnight
• Diseases of natural selection

  Humans evolved in a world which salt and sugar weren't readily available but because of industrialization, salt and sugar became abundant and thus, heart disease, stroke, and diabetes happened
• Even with variations, natural selection cannot possibly account for sudden appearance of complex organs such as the "human eye"
• Darwin's response


  Complex organs do not normally appear suddenly
• Reflex


  A relationship between a specific event and a simple response to that event, a relationship between certain kinds of events, usually events in intermediate surroundings and relatively simple forms of behaviour, mainly serve as protection to individual from injury
• Reflex examples


  • Tendency to blink when there's a dirt on your eye
  • When Amoebas encounter a noxious substance, it withdraws from it
  • Pupillary reflex (iris contracts or relaxes in response to change of light)
  • Sneezing
  • Vomit
  • Consummatory reflex
• Reflex failure


  People who consume large amounts of alcohol or drugs that depress the central nervous system, life-threatening allergies, epileptic seizures that can be triggered through lights and loud noise
• Reflexes are subject to natural selection. Those that contribute to survival will appear frequently in generations, those that are not will die out.
• Modal Actions Patterns (MAPs)

  A series of related acts found in all or nearly all members of species, also called "fixed action pattern" or "species-specific behaviour", have strong genetic basis, elicited by a "releaser" (very specific experiences), are very stereotypical, are selected because of gradual changes in the environment, serve to protect an individual from environment threats, for seasonal changes and reproduction
• Examples of MAPs


  • Salmon migration to upstream to breed
  • Pine bark beetles burrow into pine trees to find a meal
  • Spiders spin web to capture a pray, while some pounce unsuspecting prey
  • Cat hisses to threatening dog
  • Rattle snake rattles its tail when approached by an animal
  • Opossum plays dead in response to their predators
  • Hibernation of bears
• General Behaviour Traits (GBTs)


  Role of genes in determining the tendency to engage in certain kind of behaviours
• Examples of GBTs


  • Tendency to be shy or outgoing
  • Aggressive or mild-mannered
  • Adventurous or cautious
  • Anxious or relaxed
  • Obsessive-compulsive or impulsive
• Mutation


  Abrupt changes in "genes", can and cannot help as advantage (esp for significant advantage)
• Hybridization


  Crossbreeding of closely related-species, can also aid species
• Examples of hybridization


  • Grizzly bear x polar bear, hominids x ancestors
• Learning


  A "change" of behaviour due to experience, learning = change, but learning is not equal to acquisition, changes when learning occurs is behaviour
• Thinking is a form of behaviour since it is something people and animal do and it can be measured, unconscious thoughts aren't a behavour nor thoughts, feelings and emotions are behaviour as they tend to "spill out" from the body in the form of readily observed behavior
• We are just beginning to understand the biological mechanism in learning
• Defining learning as neurological change since it denies the importance of behaviour
• Behaviour is literally where it's at, changes in behaviour are not the result of learning, it is learning, learning is a result of experience
• Experience


  Changes in environment, capable of affecting behaviour, a change in behaviour due to the changes in the environment, these changes are events, and these events are called "stimuli", a stimulus is an environmental event that is capable of affecting behaviour, stimuli are physical changes in an organism's environment
• Behaviour


  • Natural Selection (modifies characteristics)
  • Learning (modifies behavior of individual)
• Habituation


  Reduction in the intensity of probability of a reflex response as a result of repeatedly evoking response, survival value of learning
• Nature vs. Nurture (Heredity vs. Learning) are interwoven "Guardian Knot" two strands cannot be separated
• BF Skinner


  "Extreme environmentalist", "Behavior requires a behaving organism which is the product in the behaviour of different species show that genetic constitution is important"
• Experiments on nature vs nurture

  • Douglas Mock's experiment of heron vs. egrets, Kuo's experiment on cats killing mice