Evolution (Theories + Scientists) - Unit 3

Question 1

What was Georges-Louis Leclerc’s (Comte de Buffon) theory?

Answer 1

Explanation:
- His volume Histoire Naturelle compiled his understandings of the natural world
- Noted the similarities between humans and apes, speculating a common ancestor and that species change over time
- Buffon proposed that Earth formed from a comet collision and estimated its age to be much older than previously believed (around 75,000 years).
- He suggested that life emerged spontaneously and species adapted to environmental changes through migration.

Contribution to Evolution:
- Buffon laid the groundwork for the concept of species transformation and natural adaptation, foreshadowing ideas of evolution and challenging the fixed species concept of his time.

Weaknesses/Flaws:
- Inaccurate Earth age estimation.
- Lack of evidence for spontaneous generation.
- No mechanism explaining species change.

Question 2

What was George Cuvier’s theory?

Answer 2

Theory Name: Catastrophism and Extinction

Explanation:
- Cuvier proposed that Earth’s history includes sudden, catastrophic events causing mass extinctions, after which new species appeared
- Used fossil evidence to show that some species (e.g., mammoths) no longer existed.

Contribution to Evolution:
- Cuvier established extinction as a scientific fact, challenging the idea that all species were created and remained unchanged
- His work laid the foundation for understanding species turnover and extinction’s role in evolution

Weaknesses/Flaws:
- No explanation for the origin of new species after extinctions.
- Overemphasis on catastrophic events (ignored gradual change).

Question 3

What was Charles Lyell’s theory?

Answer 3

Theory Name: Uniformitarianism

Explanation:
- Lyell argued that Earth’s geological features result from continuous, slow processes (erosion, volcanic activity, etc.) operating uniformly over vast periods
- Contrasts with catastrophic explanations.

Contribution to Evolution:
- Concept of gradual change provided a geological timeline essential for understanding slow evolutionary processes
- Influenced Darwin’s view of biological evolution occurring gradually

Weaknesses/Flaws:
- Underestimated past unique events (e.g., asteroid impacts).
- Lacked a mechanism for geological movements (later explained by plate tectonics).

Question 4

What was Jean-Baptiste Lamarck’s theory?

Answer 4

Theory Name: Inheritance of Acquired Characteristics

Explanation:
- Lamarck proposed that organisms change during their lifetimes through use and disuse of organs
- These acquired traits (e.g., a giraffe stretching its neck) are passed to offspring
- Also suggested life evolves from simple to complex forms

Contribution to Evolution:
- Lamarck introduced the idea that species adapt to their environment over time, pioneering evolutionary thought. - He emphasized natural processes shaping life forms

Weaknesses/Flaws:
- No genetic basis for acquired traits inheritance.
- Lacked evidence for spontaneous generation claims.

Question 5

What was Thomas Malthus’ theory?

Answer 5

Theory Name: Malthusian Theory of Population

Explanation:
- Malthus argued that populations grow faster than resources, leading to competition, famine, and poverty
- Suggested that natural limits (like food scarcity) regulate population size.

Contribution to Evolution:
- Malthus’s ideas influenced Darwin and Wallace, who applied the concept of competition and survival pressures to natural selection.
- Overproduction of offspring, leading to a “struggle for existence,” became central to evolutionary theory.

Weaknesses/Flaws:
- Overemphasis on famine and poverty as inevitable.
- Social reformers criticized his focus on population control.

Question 6

Discuss Mary Anning.

Answer 6

• Fossil hunter in England
• Her most important discovery was the first plesiosaur, an aquatic reptile
• George Cuvier examined her drawings, his acknowledgement made her respectable as a young woman in a male-dominated field

Question 7

What is Darwin’s theory?

Answer 7

Theory name: Natural Selection

Explanation:
- Species evolved from ancestral species
- Small changes in species can accumulate over time to produce new species
> Evidence; vestigial features, analogous features, variety of species (ex. finches)

Contribution to Evolution:
- Six aspects to Darwinism
> Variation: offspring of the same species are born with different variations
> Overproduction: all organisms produce more offspring than could ever survive or reach maturity
> Struggle for Existence: the young who are born far exceed the available food supply and living space, competing to exist to keep the population at an even level
> Nature Selects Favourable Variation: organisms with favourable variations survive, which is determined by nature
> Variations are Inherited: organisms with the favourable variations survive and are passed on to their offspring, which continue to pass them on
> Accumulation of Traits: After many generations, variations tend to accumulate, and create new species

Weaknesses/Flaws:
- No transitional fossils
- Could not explain how small, insignificant variations lead to the production of new structures