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Lecture 2

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Western University
Psychology 3720F/G
Doug Hazlewood

Are We Helpful By Nature? The Genetic Basis of Helping • Part 1: The origin of species: evolutionary biology o Old testament:Adam and Eve  Up until the 1700s, most scientists accented the Doctrine of Spontaneous Generation (species spontaneously appear in fully developed form from non-living matter). eg. Maggots spontaneously developed from rotting meat eg., Frankenstein o Lamark (1809)  Proposed that species developed from pre-existing species, not from dead matter. • There’s a historical continuity with development, with later species replacing earlier generation. • This was called the doctrine of evolution. o How does evolution occur?  Lamark’s two proposed ideas: • 1. He observed that an unused body part would degenerate and waste away, but if used extensively, would develop larger. He would call tehse acquired characteristics, which would stem from the use/lack of use of body size (eg. Muscles). • 2. These acquired characteristics are inherited and passed on to offspring. He said evolution would work this way: a short-necked animal would stretch out it’s nek to eat leaves on higher branches. Over it’s lifetime, the neck stretches slightly. This increase in length in inherited to its offspring, and built up upon. This may eventually become a giraffe.  Problem: characteristics are definitely acquired, btu they are NOT passed on to future generations (eg. One ex[rimet cut off the tails of mice over a lot of generations. No decrease in tail size was observed over the course of these successive generations).  We still have this question about how evolution works.  Interestingly, the year that Lamark published his theory, Charles Darwin was born. • He went on a 5 year journey, and spent 20 years after that sifting trhough the data. With this he developed the theory of evolution. Interestingly, at around the same time, Wallace in 1858 thought up the same theory. o According to them, evolution works via natural selection o Darwin published On the Origin of Species in 1859. o The theory was based on 3 observations and 2 conclusions:  Observations: • 1. Without enviro pressures, every species is capable of multiplying geometrically (eg. 2^n, where n is the number of generations). • 2. Under natural conditions ( with pressures), the size of a population remains ~constant over long periods of time. • 3. Not all members pf a species are the same (variation exists within even the same species).  Conclusions drawn from the observations • 1. From first two observations (1 & 2): Not all individuals will survive and reproduce. There must be a struggle for existence/life. • 2. From observation (3): Individuals who have varourable variations/characteristics are more likely to survive and produce offspring who also have these favorable characteristics. This process was called Natural Selection, which results from the “survival of the fittest”. NOTE: fitness in this context means reproductive success. It refers entirely to the number of offspring that are produced.  This theory was challenged almost immediately by other scientists. It generated quite a bit of criticism. Three main criticisms of Darwin’s Theory: • What’s the source of this important variation between indivdiuals? Why do people differ between each other? The theory cannot work without this variation, and Darwin’s original theory couldn’t answer this question. • How do “new” variations come about? If it just selects for what is alrady there, what is the source of these variations? Eventually we would be without variation due to the selection, which only decreases variance. • How do these new characteristics get passed on to future generations? What is the mechanism? Darwin knew nothing about genes, so he didn’t have an answer.  Despite the criticisms, he gave a foundation for what is now called the Modern Synthesis: • Modern Synthesis: Combine Darwin’s ideas about natural selection with modern ideas about genes and genetic transmission. • Modern Synthesis answers each of these criticisms. Genes provide the source of this variation (genes for brown vs. blue eyes). They also explain how the variations come about; mutations, which may produce new genes.Avery small amount of these mutations are helpful, and are selected for.And genes, of course, are also a form of hereditary transmission to future generations. Could helping behavioural evolve through the process of Natural Selection? • YES, if helping increases the fitness of the helper (eg., if it’s “selfish”, and benefits the helper), then Darwin’s theory could account for this. • BUT what about altruism? “Behaviour that increases the fitness of the recipient and decreases the fitness of the helper.” When defined this way, altruism poses some problems for Darwin’s theory. They still help, but it decreases their odds of surviving and producing offspring. Hard ti imagine this behaviour evolving through the process of natural selection, since they are less likely to have offspring. o According to his original theory, no species should be altruistic by nature. o Yet there are quite a few who practice altruism.  Eg., alarm calls (robins chirp, so signal surrounding birds of a predator nearby. Deer snort for the same reason. Gazelle jump into the air. Vervet monkeys have four different alarms; enemies that fly, climb trees, on the ground, and one just for snakes). These alarm calls are good for other members of the group, but not so good for the individual caller, who calls attention to him or herself, and increases the odds of them getting caught. • Actually, it’s selfish. It does benefit the helper. Eg., a robin who raises the alarm signals the other robins to take flight.All these flying robins make the alarm caller less conspicuous, and it’s capable of escaping in the crowd. The predator may lose focus on the alarm caller when it’s distracted by the giant flock that just took flight. It’s momentary attention. Eg., when a gazelle hops, it gets a better view of the surrounding territory, so it can see over the tall grasses and know which ways to run. It also allows the gazelle to see if there are other predators nearby. It also tells the predator “I’m strong, I’m healthy, and I know that you’re there. Don’t mess with me.” • Another example, cooperation (eg., wolves), is also selfish, because while helping others, the helper is also helping itself. • Reciprocity is a special form of cooperation. It’s basically “I’ll help you now, so you will help me in the future”. Both individuals benefit. o Eg., Grouper (a big fish that likes to eat small fish) and Wrasse (a small fish, but the grouper never eats it) the grouper will even open it’s mouth and let the wrasse go into it’s mouth to scavenge for food.  While scavenging for food, the wrasse eats parasites that live in the grouper’s mouth and gills. This is reciprocal. The grouper gets rid of it’s parasites, and the wrasse gets a free meal. o NOTE: for reciprocity to be evolutionarily successful, special conditions are necessary (see pp. 50-51 of the readings for this week). o BUT some behaviours appear to be truly altruistic. For example, let’s take a look at the social insects: ants, termites and bees (some call them paragons of altruism).  Eg., soldier ants never retreat in the face of the enemy. They will always fight to the death in order to protect the colony. But at least the ants can survive. Soldiers in the termite colony have a literally suicidal battle technique. When confronted with an enemy (usually an ant), the termite spits out sticky yellow stuff that now only traps the enemy, but also itself. Both die. But at least now one less enemy is a threat. What about bees? They protect the hive, but also are likely to die doing so. They have barbed stingers, which get stuck in the enemy. To leave the prey after stinging, the stinger is pulled off and is stuck in the enemy (can’t be easily removed), but the bee is disemboweled. The abdomen actually falls off the bee, and it continues to pump venom into the enemy. The bee dies.  Even Darwin admitted that the behaviour of these insects is a huge challenge for his
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