Lec 8

Page 2: Evolutionary Theory Overview

• Key Theorists: Alfred Russel Wallace and Charles Darwin

• Focus: Consequences of evolutionary theory

• Assignments: Homework-4-9

• Study Materials: Required readings and video to align with lecture topics

• Reference: Chapters 1, 22, 14

Page 3: Observations Impacting Wallace's Theory

• Biogeography: Study of species distributions over time and geography

• Specific Case: Malay Archipelago; the proximity of Bali and Lombok (15 miles apart, tropical environment)

• Significance: Challenges Wallace's assumption of similarity due to geographical closeness

Page 4: Questions on Species Similarity

• Discrepancies in species despite geographical proximity raised critical questions for Wallace

Page 5: Geological Insights from Wallace

• Hypothesis: Species differences on nearby islands resulted from geological shifts

• Support: Influenced by Charles Lyell's work

Page 6: Wallace's Line Evidence

• Findings: Underwater fault line separating Australian and Asian species

• Implications: Reproductive isolation due to tectonic plate movements

Page 7: Charles Darwin and Alfred Russel Wallace's Journey

• Darwin's Voyage: 5-year journey on the Beagle (1831-1836)

• Idea Development: 22 years contemplating a major evolutionary work

• Career Struggles: Collection of specimens to financially support his research

• Publications: Key works published between 1855-1858 focusing on variation, adaptation, geographical isolation, and evolution mechanisms

Page 8: Essential Observations on Evolution

• Darwin and Wallace's Main Observations:

  1. Variation exists within populations

  2. Variation is heritable

  3. Not all offspring survive to reproduce

  4. Species align closely with their environments

  5. Geographic distance correlates with trait differences

Page 9: Key Publications by Darwin and Wallace

• Darwin's Key Works:

  • On the Origin of Species (1859)

  • Descent of Man (1871)

• Wallace's Contributions:

  • On the Tendency of Species to Form Varieties (1858)

• Joint Presentation:

  • Presented to the Linnaean Society, July 1, 1858, with Darwin's and Wallace's ideas

Page 10: Differences in Focus

• Darwin vs. Wallace:

  • Darwin emphasized competition among individuals

  • Wallace focused on environmental and ecological pressures leading to adaptation

• Historical Perspective:

  • Noted differences in their approaches despite similar conclusions

Page 11: Environmental Context of Fitness

• Wallace's View: Environmental conditions determine fitness, making advantageous traits context-dependent

• Example: Size and strength are relative to the environment's demands

Page 12: Darwin's Theory of Species Origin

• Key Aspects:

  • Species originate from ancestral forms

  • Divergence occurs via Natural and Sexual Selection

• Introduction of Branch Method: First representation of evolutionary relationships

Page 13: Darwin's Recognition and Background

• Published pivotal works in 1859

• Social Standing: Influenced by Darwin's aristocratic background

• Public Relations: Greater acceptance and promotion of Darwin compared to Wallace

Page 14: Public Reception of Darwin's Ideas

• Heterodox Nature: Darwin's theories, particularly on human descent from apes, faced societal backlash

• Emerging Popularity: Gained traction through Victorian society despite initial challenges

Page 15: Social Context of Darwin's Theory

• Victorian England: Class disparities influenced scientific discourse

• Concept of Individualism: Economy of self-interest found relevance in Darwin's theories

Page 16: Misappropriation of Science

• Scientific Authority: Utilized to promote sociopolitical agendas

• Concern: The phrase "survival of the fittest" was hijacked for non-scientific purposes

Page 17: Eugenics Movement

• Origin: Developed by Sir Francis Galton, Darwin's cousin

• Concept: Misinterpretation of natural selection leading to societal manipulation of reproduction

• Focus: Advocated for selective breeding to perpetuate "superior" traits

Page 18: Galton's Analysis of Traits

• Pedigree Analysis: Suggests brilliance and other traits are hereditary

• Male-Specific Trait Notion: Implications raised concerning gender-based inheritance

Page 19: Historical Perspectives on Eugenics

• Key Figures: Joseph Stalin and Theodore Roosevelt

• Opposition: Varied views on eugenics linked to political ideologies

Page 20: Science Informing Policy

• Legislation Examples:

  • 1924 Virginia’s Racial Integrity Act: Defined racial categories

  • 1924 Virginia Sterilization Act: Legalized sterilization of perceived "undesirables"

Page 21: Defining "Undesirables"

• Target Groups: Individuals with cognitive or physical disabilities labeled as "feeble-minded"

• Notable Examples:

  • Figures impacted by these definitions included historical luminaries like Einstein and Hawking

Page 22: Discussion Questions

• Topics for Consideration:

  1. Significance of Wallace & Darwin independently conceiving evolutionary theory

  2. Locations of Wallace's major discoveries

  3. Explanation of Wallace's Line and its significance

  4. Implications of ARW's observations of species variation

  5. Prevailing views on life's diversity during ARW and CD's time

  6. Influence of contemporary views on their hypotheses

  7. Speculation on ARW's impact had he not sent his manuscript to CD

  8. Examination of Darwin's influence leading to eugenics and sterilization laws