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Earth's Evolution: From Past to Present

Explore the history of Earth, from its formation 4.6 billion years ago to the emergence of life and the evolution of species. Learn about index fossils, carbon dating, extinctions, and the 6th extinction crisis. Discover how life originated, from the primordial soup to endosymbiotic theory. Understand evolutionary patterns like punctuated equilibrium, adaptive radiation, coevolution, and convergent evolution.

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Earth's Evolution: From Past to Present

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  1. Question: Homework: • How many species that once lived onEarth do you think are still present today?Give a % • p. 422 #1, 2, p. 440 #2, 5 • (lab) Comparing Bird Adaptations

  2. The History of the Earth

  3. Earth's Timescale • 4.6 Billion Years Old • 4 BYA- early life originates • 3.2 BYA- oxygen released into atm. • 2.1 BYA- first eukaryotes • 530 MYA- first life on land • 246-144 MYA- dinosaurs • 150-160 KYA- earliest Homo sapiens on Earth

  4. Origins of Life • Early Earth’s atmosphere • NO ORGANIC COMPOUNDS • contained building blocks (Carbon, hydrogen in various compounds • Organics require lots of energy to form • Thought to have formed as result of lightning • bubbles made holding organic cpds.

  5. How we know- • Index Fossils • Fossils used to be compared to other unknown fossils • Can see relative age • if above, = younger • Carbon Dating • Method of using radioactive carbon to give date fossil was formed • Can use these two to give dates that different species existed on Earth

  6. Extinction • By looking at fossil records, can see 5 major extinctions in Earth’s history • last one 65 MYA- dinosaurs along with MANY others • The 6th extinction? • Currently, species disappearing at rates unparalleled in Earth’s history • Caused by humans?

  7. How life came about? • Primordial soup • Molecules present on early Earth • Combined with energy added, can make organic compounds • made simple bacteria • lipid surrounding DNA

  8. How life came about? • From bacterial life to multicellular life… • **Endosymbiotic theory • one bacteria ingested another, and developed the ability to work with that structure • over time, different bacteria with different functions were taken in, resulting in the modern eukaryote • evidence: mitochondria with their own DNA!!!

  9. Patterns of Evolution • Punctuated Equillibrium • Adaptive Radiation • Coevolution • Convergent Evolution

  10. Punctuated Equillibrium • Theory to explain that long periods of equillibrium exist, followed by short, rapid phases of evolution • Generally follow mass extinctions in Earth’s history • **WHY?

  11. Coevolution • When two species evolve in response to each other • *Think of snake and newt as example- • one develops greater toxicity to protect itself, while other evolves higher resistance to toxicity

  12. Adaptive Radiation • When one species evolves into a number of different species • Think about Darwin’s finches- • began as one species, but evolved into 14 different species depending on the niche being filled

  13. Convergent Evolution • When two species evolve similar, but distinctly different structures • Ex- bat wing and fly wing

  14. Question: Homework: • How is the “6th extinction” different from the 5 • prior extinctions in Earth’s history? • p. 422 #1, 2, p. 440 #2, 5 • (lab) Comparing Bird Adaptations

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