Today’s Topics
•
This Part of Course will Address the Questions:
–
Where Did We
Come From?
–
How Does Our
Biology Influence Our Behavior & Culture?
–
What Can We
Learn About Ourselves from Our Closest Relatives?
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Evolutionary Biology
–
Darwin—Natural
Selection
–
Mendel—Genetics
–
Biology
& Behavior
•
Our Closest Relatives—The Primates
Pre-Darwinian Beliefs: Biblical &
Classical Interpretations
•
Created by God (The Grand Design)
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No Change
•
Very Young Earth
•
Great Chain of Being
•
Aristotle
•
Linear
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Simple to Complex
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Static / Non-Evolutionary
Carolus Linneaus (1707-1778)
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Swedish Naturalist
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Systema Naturae (1735)
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Classification System of Plants & Animals
• Taxonomy
• Binomial Nomenclature
•
Static
Jean Baptiste Lamarck
(1744-1829)
•
Tried to Explain Evolution
•
Interaction with Environment
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Inheritance of Acquired Characteristics
–
Acquire
characters during life
–
Pass on to
offspring
Lamarck’s View of Evolution
Charles Lyell (1797-1875)
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Scottish Geologist
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Founder of modern geology
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Principles of Geology
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Uniformitarianism, not Catastrophism
•
Old Earth
Charles Darwin (1809-1882)
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Studied Medicine & Theology
•
Edinburgh University
•
Cambridge
•
Voyage on HMS Beagle (1831-1836)
Voyage of the HMS Beagle
•
5-year voyage around world
•
Biological
& Environmental Variation
Galapagos Island Fauna
•
Fauna similar to that on mainland (South America)
•
But…
•
No land mammals
•
Those birds & reptiles present have more variation within
groups
•
Finches & tortoises
Darwin’s Post-Voyage Years
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Species not fixed
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Island species showed origin with local adaptation
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Fossils as remnants of extinct life forms
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All living organisms came from a common ancestor
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Processes of today same as occurred in past
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These processes take lots of time
Natural Selection
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First used in 1842
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Borrowed from “Selection” from Animal Breeding
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Evidence from Animal Breeding
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Influenced by Lyell & Thomas Malthus
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“Struggle for Existence”—Competition for Limited Resources
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“Survival of the Fittest”—More Offspring Born Than Can Survive
•
Uniformitarianism
•
“Pushed” Forward by Wallace
Darwin’s Evidence
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Domesticated Animals (Artificial Selection)
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Selective Breeding Experiments
Darwin’s Evidence (Comparative Anatomy)
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Homology
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Similarities based on descent (e.g., limb bones)
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Analogy
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Similarities in unrelated organisms based on similar adaptations
(e.g., eyes or wings)
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Vestigial Structures
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Retentions with no function (e.g., pelvic bones in whales)
Homologous Traits
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Similar structures, often different functions
Analogous Traits
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Similar functions, different structures
Vestigial Structures
On the Origin of Species (1859)
• “Much light
will be thrown on the origin of man and his history”
Darwin’s Problems
•
Darwin Could Not Explain:
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How Traits Were Inherited
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How Variation Originated and Was Maintained
Mendel & Genetics
Gregor Mendel (1822-1884)
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Austrian Monk
•
Pea Plant Experiments
•
Mechanism of Inheritance over Generations
Mendel’s Question
•
How Are Traits Inherited From One Generation to Next?
-Blending or
Discrete?
Mendel’s Experiments
Inheritance
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Not Blending, Instead Particulate
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Principle of Dominance
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Dominance
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Recessive
Genes & Alleles
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Mendel Called These “Factors”
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Genes: Section of DNA with Identifiable Structure or Function
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Alleles: Different Forms of a Gene
Principle of Dominance
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Gene for Seed Color
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Two Possible Alleles
• C = Yellow
• c = Green
• Yellow Dominant
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Two Alleles for Each Gene
• 1 from Mother
• 1 from Father
Genotypes & Phenotypes
•
Phenotypes: What You See (Expression of Genes)
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Yellow or Green Seeds
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Genotypes: Genetic Makeup; What Alleles are Present
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CC or Cc or cc
•
CC = Yellow
•
Cc = Yellow
•
cc = Green
Law of Independent Assortment
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Traits are Inherited Independently of One Another
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Seed Color Won’t Influence Plant Height
DNA & Chromosomes
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DNA (Deoxyribonucleic Acid) Makes Up Genes
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Genes Located on Chromosomes
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23 Pairs of Chromosomes (1 of each pair from mother and 1 from father;
46 Total) in Each Body Cell
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Sex Cells Have only Half (23)
Schematic showing DNA & Chromosomes
Evolution in Humans
Forces of Evolution
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Natural Selection
•
Mutation: Change in DNA (An Error)
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Genetic Drift: Random Change in Gene (Allele) Frequencies in Small
Populations
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Gene Flow: Exchange of Genes Between Populations