Chapter 2 Part 1 - Biological Roots of Behavior (part 1)...

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Today’s topics Evolution Genes Homeostasis Eating Biological Roots of Behavior (part 1)
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Evolution Evolution : The process by which characteristics of a species change from one generation to the next Charles Darwin Published Origin of Species (1859) – theory of evolution Naturalist on HMS Beagle , collecting animal and plant specimens (1831) – Observed differences in finches on Galapagos Islands Chapter 2: The Evolutionary Roots of Motivated Behavior
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Adaptation to Environment Darwin noticed that finches on different islands had different types of beaks – Type of beak seemed to match island’s food supply Strong, thick beaks (where food supply rich in nuts and seeds) Smaller beaks (where food supply had abundance of insects) – Beaks suited to feeding on plants and flowers (where food supply had abundance of vegetation) Darwin: Each subspecies had become adapted to its particular environment! Chapter 2: The Evolutionary Roots of Motivated Behavior
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Competition for Resources Thomas Malthus – British economist Organisms produce offspring at a pace that outgrows food supplies, living space, other crucial resources – Competition for resources – some survive, others don’t Darwin: Which individuals would survive and which ones wouldn’t? – Finches with certain type of beak more likely to survive and reproduce Chapter 2: The Evolutionary Roots of Motivated Behavior
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Natural Selection Darwin: Offspring resemble parents in many ways – Finches with certain type of beak more likely to survive AND more likely to have offspring with same beak type – CONCLUSION: each successive generation has more finches with adaptive beak type and fewer with maladaptive beak type Natural Selection – tendency for individual organisms with particular traits that contribute to that organism’s survival and reproduction, to produce more offspring, causing that trait to be more prevalent in the next generation Natural selection results in evolutionary change! Survival is important, but the key is reproduction ! Chapter 2: The Evolutionary Roots of Motivated Behavior
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Genes Genes Basic building blocks of heredity Blueprints for cells to reproduce themselves and direct organism’s development Consist of molecules of deoxyribonucleic acid (DNA) Each gene is a section of a chromosome Chromosomes Larger strand of DNA molecules Each chromosome consists of over 1,000 genes Exist in nucleus of cells Every cell (except sex cells) has 23 pairs (46 total) Chapter 2: The Evolutionary Roots of Motivated Behavior
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Dominant & Recessive Genes Genes come in pairs Each gene has a specific position on its chromosome “partner” gene is on corresponding location on “partner” chromosome Pairs of genes may be the same or different Homozygous – both genes the same Heterozygous – two genes are different dominant gene Causes dominant trait to be expressed e.g. brown-eye gene is dominant over blue-eye gene
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Chapter 2 Part 1 - Biological Roots of Behavior (part 1)...

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