Evolution

• The goal of science is to explore and understand the natural world
• Up until the 1800's, many people believed that the Earth and its inhabitants were only a few thousand years old and that it was no different now than when it had been created
• Geologist James Hutton


  Published a book in 1795 explaining how geologic forces shaped Earth extremely slowly over time
• Hutton's observations


  • Layers of rock are formed very slowly
  • Some rocks are pushed upward by forces beneath the surface, which result in the formation of mountains
  • Mountains and valleys are then shaped by wind, rain, and not ice temperatures
• This meant Earth had to be much older than believed!
• Thomas Malthus


  An English economist who in 1798 published his Essay on the Principle of Population, stating that the birth rate was exceeding the death rate, which meant that if left unchecked, sooner or later there would be insufficient living space and food for everyone
• Jean-Baptiste Lamarck


  In 1809, proposed his Theory of Acquired Characteristics, stating traits are developed and passed on through USE or DISUSE. The more a trait was used by an organism, the bigger and better it got over generations. Similarly, traits that were under-utilized, would shrink from disuse
• Charles Lyell


  In 1833, published his book Principles of Geology, which argued that Earth's land itself has changed over time by the same natural processes that continue to shape Earth's landscape even now. This is known to scientists as uniformitarianism. That meant, to understand what happened THEN, you need only study the forces happening now
• Charles Darwin was born on the same birthday as Abraham Lincoln!
• H.M.S. Beagle


  A 5-year survey expedition of the South American coast and other lands in the southern hemisphere, on which Darwin was appointed as naturalist
• Darwin's observations on the Beagle

  • Birds who couldn't fly
  • Iguanas who could swim
  • Tortoises with different shells
  • Finches with differently shaped beaks

  
• Darwin waited 20 years to publish his findings from the Beagle voyage; he needed much more data from experimentation before he could understand the mechanism (the HOW) of evolution
• The Origin of Species

  Darwin's famous book where he first proposed the Theory of Evolution by Natural Selection
• Survival of the fittest

  The phrase summarizing Darwin's theory, meaning those organisms with the best adaptations for an environment will survive and reproduce
• Overproduction


  Organisms produce more offspring than can survive
• Struggle for Existence


  Offspring must compete for resources and cope with environmental stressors
• Variations


  Small differences among members of a species, resulting from sexual reproduction and genetic mutations
• Adaptation


  Any trait that helps an organism survive and reproduce
• If an environment is a set of problems, then an organism's adaptations are their solutions to them
• Selection


  Organisms who can respond favorably to an environment's challenges will survive and reproduce
• Fossils are any remains of life from an earlier time
• Structures that are similar in origin and structure but retain differences in size and do not appear to serve an organism's development suggest a common ancestry
• Similarities in DNA sequences among different organisms suggest a common ancestry