29.2 explanation of evolution


Published on

  • Be the first to comment

  • Be the first to like this

29.2 explanation of evolution

  1. 1. 29.2Explanation for Evolution
  2. 2. Darwin’s Work• Charles Darwin studies natural selection in the Galapagos Islands over 200 years ago• He published a book on his finding and made several important points• Livings things over produce. More offspring are produces than survive
  3. 3. 2. There is a variation among offspring. A variations is a trait that makes an individual different from others of its species3. There is a struggle to survive There are more living things than there are resources to go around. This results in competition. Competition is the struggle among living things to get their needs for life, such as food, water, shelter or mates
  4. 4. 4. Natural selection is always taking place Individuals with less desirable traits are less fit. Those with more desirable traits are more fit and reproduce more. The traits that make them more fit are the ones that are passed on to new generations.
  5. 5. Darwin knew this occurred very slowly and led him to a theory called evolutionEvolution is the change in the heredity features of a group of organisms over time.When a species changes over time the term evolved, is used
  6. 6. Fossil Evidence• Fossils are the remains of once living things from ages past• A fossil can be a print of a leaf, a footprint, bones, an animal frozen in a glacier or an insect trapped in hardened plant sap• Scientists can compare things from the past to things that are known today and record the changes that have taken place
  7. 7. • Most fossils are from extinct organisms. Extinct means no longer alive• Many fossils are found in the sedimentary rocks found in the earths crust• Sedimentary rocks form from mud, sand and fine particles and form at the bottom of seas.• Animals die and settle into the bottom of these waters and after millions of years form into rock• Fossils form into these rock layers and give us a record of the types of living things on earth at that time.
  8. 8. • By carbon dating scientists are able to date the age of the fossils• Fossils found at the bottom of sedimentary rocks are the oldest.
  9. 9. • Other evidence• Many embryo’s have common traits and have common ancestry because of common DNA.• Some species have vestigial structures, that is structures that no longer serve a purpose.• Examples in mammals include the appendix. In humans it is not needed, but in rabbits it is used to digest grass. The pink lump in the corner of your eye is the remnant of a third eye lid, such as those in frogs and other amphibians
  10. 10. changes in fossils similarities in embryosEvidence of Evolution gene code vestigial structure