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.