Charles Darwin and Evolution Evidence

Introduction to Charles Darwin and Evolution Evidence

  • Overview of Charles Darwin's significance in the field of science
    • Celebration of his contributions on his 200th birthday by prominent scientists like James Watson and E.O. Wilson.
    • Watson's praise of Darwin: despite lacking knowledge of DNA, he laid the groundwork for understanding evolution.
    • E.O. Wilson's acknowledgment of Darwin's work in explaining the origin of species.

The Missing Link: Tiktaalik

  • Discovery of Tiktaalik:
    • A 375 million-year-old fossil found in Ellesmere Island, Canada.
    • Sheds light on the transition from sea creatures to terrestrial animals.
    • Key physical features of Tiktaalik:
    • Fins and scales, but more similar to a four-legged creature than a fish.
    • Features resembling the human arm structure (e.g. shoulder, elbows, evolving wrist structure).
    • Scientists, including Neil Shubin, predicted its existence based on geological strata.

Importance of Evolution in Biology

  • Theodosius Dobzhansky's quote:
    • “Nothing in biology makes sense except in the light of evolution.”
    • Evolution now included in biology textbooks after his assertion.

Core Principles of Evolution

  • Definition: Evolution explains similarities and differences among living things but does not address the origins of life itself.
    • Early cell evolution and mutations leading to diverse species.
  • Common ancestry: All life is connected through common ancestors.
  • Darwin's terminology:
    • Did not use "evolution"; focused on "change" and "natural selection."
    • Thomas Huxley, "Darwin's Bulldog," coined the term evolution.

Natural Selection and Environmental Influence

  • Environmental factors affecting evolution:
    • Examples include temperature, humidity, and nutrient levels.
  • Favorable traits become more common (descent through modification).

Example of Evolution: Antarctic Ice Fish

  • Overview:
    • Approximately 200 species evolved 55 million years ago, adapting to cold waters (30° Fahrenheit).
  • Unique adaptations:
    • Cold-adapted tubulin proteins ensuring cell reproduction in cold conditions.
    • Reduced red blood cell count leading to thinner blood for easier flow.
    • Loss of globin genes affecting hemoglobin and myoglobin.
    • Increased heart size to pump cold liquid efficiently.
  • Impact of climate change on the Antarctic ice fish:
    • Rising temperatures threaten adaptive capabilities, risking extinction.

Conditional Nature of Fitness

  • Sean Carroll’s quote:

    • Highlights that an organism's fitness is conditional and can be compromised by rapid environmental changes.

  • Preview of upcoming discussions:

    • Continuing with Charles Darwin and the theory of evolution in part two.