Sci Week 5

• Evolution is the gradual change in a population's genetic and physical traits
• Organisms come in different shapes and sizes, some animals can fly or swim, flowers have different colors, and humans look the way they do because of evolution
• Scientists discover many things that lead them to further believe in the process of evolution through the help of some evidences
• Evidences of evolution


  • Fossil records
  • Comparative anatomy
  • Embryonic development
  • Genetic information
• Fossils


  Remnants or remains of ancient organisms that give us a picture of how organisms have changed over time
• How paleontologists determine the age of a fossil

  • Position in the sedimentary rocks (fossils in bottom layer are older)
  • Using the Geologic Time Scale
• The Earth is about 4.5 billion years old according to the Geologic Time Scale
• The Geologic Time Scale is divided into Eon, Era, Period, and Epochs
• Comparative anatomy


  The study of the body structures of animals to know how they have evolved from the likes of their common ancestors for the purpose of adapting to their environment
• Homologous structures


  Similarities in the body structures of different species, which may have come from common ancestors, even if the structures do not have the same functions
• Homologous structures


  • Forelimbs of human and cat
  • Forelimbs of whales and bats
• Analogous structures


  Structures that have the same function but are not evidence that they came from a common ancestor, the similarity only reflects similar needs brought about by the environment
• Analogous structures


  • Bird's wing and bat's wing
• Embryonic development


  The study of developing organisms or embryology, used to compare one organism to another to see how they are related
• Vertebrate embryos look alike in their early stages
• Genetic information


  The biochemical analysis and amino acid sequence of organisms' DNA, the greater the similarity, the closer the relationship of the organisms
• Differences in amino acid sequence between humans and other organisms

  • Fruit fly - Pigeon
  • Fruit fly - Wheat
  • Human - Horse
  • Human - Wheat
• Organisms which are similar in structure and also possess similarity at the biochemical level could probably have a common ancestor