Evolution and Natural Selection Notes

Introduction

• Why didn't the ancients fly jets or King Tut have an iPhone?
• Missing pieces: Evolution is about putting the pieces together.

Key Figures and Ideas

• Malthus: "Survival of the fittest" (in humans).
• Linnaeus: Interrelatedness of life, taxonomy.
• Hutton & Lyell: Geology, gradualism, uniformitarianism; the world is old.
• Cuvier: Paleontology, species transition, timeline of species, extinction.

Charles Darwin

• Early Life:
  • Grew up at age fifteen.
  • His father, Robert Darwin, a successful and wealthy doctor, worried about his future.
  • Sent to medical school in Edinburgh but dropped out because he couldn't stand the sight of blood.
  • Father tried to secure a position for him in the church, requiring enrollment in Cambridge University.
  • Showed less interest in formal education and hated memorizing things, preferring the outdoors and nature.
  • Enjoyed observing birds and taking notes of their differences.
• Turning Point:
  • Managed to earn a bachelor of arts in May 1831.
  • Received an offer from Professor Henslow to travel on a ship voyage across the globe to collect life and mineral specimens.
  • His father was initially against the offer, but Darwin eventually accepted it.
• The Voyage:
  • After four years on the voyage, returned home in 1836, transformed in body and spirit.
  • His father was finally happy for him.
• Significance:
  • Charles Darwin (1809-1882) was an English naturalist, geologist, and biologist.
  • Best known for his contributions to the science of evolution.
  • Described as one of the most influential figures in human history.

Natural Selection

• Key Principles:
  1. Over Reproduction
  2. Individual variation (caused by mutations)
  3. Competition
  4. Limited survival (Survival of “Fitter”)
  5. Differential Reproductive Success (Genes of the survivors become common, less “fit” genes decline.)
  6. Time (many small changes lead to large changes)
• Natural Selection: result of these natural facts.

Discoverers of Natural Selection

• Charles Darwin (1809-1882) in 1859.
• Alfred Wallace.

Pre-Darwin Discoveries

• World is old.
• Species evolve (change over time).
• Forces are the same now & in the past - Change is very slow.
• Competition – “Survival of the fittest”.
• Species have varying degrees of similarity (relatedness).

Historical Context of Darwin's Life and Ideas

• 1795: Hutton proposes his theory of gradualism.
• 1798: Malthus publishes "Essay on the Principle of Population."
• 1809: Lamarck publishes his theory of evolution.
• 1830: Lyell publishes Principles of Geology.
• 1831-1836: Darwin travels around the world on HMS Beagle.
• 1837: Darwin begins his notebooks on the origin of species.
• 1844: Darwin writes his essay on the origin of species.
• 1858: Wallace sends his theory to Darwin.
• 1859: The Origin of Species is published.
• 1865: Mendel publishes inheritance papers.

Carl Linnaeus (1707-1778)

• Taxonomy mirrors evolutionary descent/relatedness.
• Taxonomic Classification:
  • Domain: Eukarya
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Carnivora
  • Family: Canidae
  • Genus: Canis
  • Species: Canis lupus

Georges Cuvier

• Father of Paleontology (fossils).
• Key Discoveries:
  • Species transition (over time).
  • Timeline of Species.
  • Species EXTINCTION.

Formation of Sedimentary Rock and Deposition of Fossils

1. Rivers bring sediment to the ocean. Sedimentary rocks containing fossils form on the ocean floor.
2. Over time, additional strata are added, containing fossils from each time period.
3. As sea levels change and the seafloor is pushed upward, sedimentary rocks are exposed. Erosion by rivers reveals strata; older strata contain older fossils.

James Hutton (1726 – 1797)

• Gradualism: Profound geologic change is slow (1" at a time).

Charles Lyell (1797-1875)

• Confirms World is Very OLD!
• Uniformitarianism: Geologic processes: same now & in past.

Conclusions

1. Earth very old
2. Slow changes → big changes over time
3. Species change over (long) time (*mechanism unknown)

Jean Baptiste Lamarck (1744-1829)

• Hypothesis: Inheritance due “Use and Disuse” of traits to adapt to the environment.
• Species not Fixed (evolve).

Thomas Malthus (1766-1834)

• "Survival of the fittest" (in humans).
• Populations limited by environmental factors (ex. food).
• Thus, competition.

Charles Darwin (12 February 1809 - 19 April 1882)

• & Natural selection

Darwin's Early Life and Education

• Born 1809, 5th child of Dr. Robert Darwin.
• Medical School (1825): Distracted by interest in the natural world, “dislike of blood”.
• Christ’s College (1828-31): Divinity school (to become Parson), graduated (Jan 1831).

HMS Beagle Voyage

• Offered position on HMS Beagle (Aug. 1831) by Henslow.
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