Lecture on Charles Darwin and the Theory of Evolution

Introduction to Charles Darwin

• Famous scientist from the 1800s.
• Known for developing the theory of evolution.
• Passionate about animals and their study.

Darwin's Voyage on the HMS Beagle

• In 1831, Darwin embarked on a voyage on the HMS Beagle.
• Travelled to South America and Australia.
• Observed and collected various unique plants and animals.

Observations in the Galapagos Islands

• Found around 15 different species of finches.
• Noticed similarities among finches but differences in beak shapes.
• Beak shapes were related to the type of food available:
  • Finches eating insects had skinny, pointed beaks.
  • Finches eating hard fruits had sharp beaks.

Development of Evolutionary Ideas

• Realized birds adapted to their environments over time.
• Introduced the concept of "survival of the fittest":
  • Organisms with traits best suited to their environment are more likely to survive and reproduce.
  • Over time, these traits become predominant in the species.

Example of Natural Selection: The Peppered Moth

• Initially, 98% of peppered moths were light-colored in early 1800s London.
• Light-colored moths blended with tree color, avoiding predators.
• Industrial revolution caused trees to turn black with soot.
• Dark moths gained survival advantage and by 1895, made up 95% of the population.
• Illustrates natural selection, which typically takes longer.

Human Evolution

• Darwin suggested humans share a common ancestor with modern apes.
• This idea was controversial due to conflicting religious beliefs.

Impact of Darwin's Theory

• Theory of evolution by natural selection had a significant impact globally.
• Widely accepted today as the best scientific explanation of life on earth.