Evo

• Biological evolution

  Any change in the inherited traits of a population that occurs from one generation to the next
• Homology


  Characteristics shared among related individuals because of common ancestry
• Synapomorphy


  A derived characteristic shared among a common ancestor and its descendants
• Phylogeny


  Evolutionary history of a lineage
• Aquatic organisms like whales and fish


  Have evolved similar body forms
• Fossils representing the transition of land to water provide information of the details of this transition
• Independent lines of inquiry enrich our understanding of the mechanisms of evolution
• Natural selection


  Favors flu variants that evade the immune system
• Reassortment


  Can result in strains that are both deadly and highly infectious
• By continual monitoring, scientists can catch the evolution of new strains as they emerge
• Evolution is a tapestry of complex phenomena that operate in both the short and long term
• The "Great Chain of Being," which ranked life on a scale, was the dominant view of biodiversity for two millennia
• Carolus Linnaeus classified life into nested hierarchies, a system still used today
• Nicolaus Steno, the founder of geology, pioneered use of stratigraphy as a method for reconstructing the past
• William Paley proposed that mechanical complexity of animals provided evidence for a Divine Creator
• Georges-Louis Buffon


  Proposed that varieties of species arise in response to new habitats
• Georges Cuvier


  Anti-evolutionist; concluded that living things had gone extinct
• Mary Anning (1799–1847) discovered several species of extinct marine reptiles
• James Hutton


  Argued that Earth transformed gradually over vast amounts of time
• William Smith


  Used distinct groups of fossils; produced first geological map
• Jean Baptiste-Lamarck


  Proposed that species evolve through natural processes; Claimed that adaptation occurred through inheritance of acquired changes
• Charles Lyell


  Argued that Earth changes gradually
• Comparisons between embryos reveals homologies not evident in adults
• Thomas Malthus


  Human population size limited by resources; Essay influenced Darwin's thinking
• Darwin proposed natural selection as a mechanism that explains evolution
• Alfred Russel Wallace independently formulated the idea of natural selection
• Some early estimates of Earth's age, such as Kelvin's, were based on flawed assumptions
• Isotopes


  Atoms of the same element with different numbers of neutrons
• Unstable isotopes


  Have a fixed probability of decay
• Isotopes with high decay probabilities


  Decay more quickly; isotopes with low decay probabilities decay more slowly
• The fossil record can never be complete because most organisms don't fossilize
• Technology allows scientists to gain insights into the natural history, behavior, and appearance of extinct organisms
• Isotopes and biomarkers carry information about the history of life
• Earth formed 4.568 billion years ago from the primordial solar disk
• The surface of early Earth cooled, producing a planet with a solid crust and a molten interior
• Early Earth's atmosphere formed as rocks released gases and H2O vapor
• H2O vapor condensed, filling basins and defining continents
• Earth had a tumultuous beginning, and very little rock material from then remains
• Ancient rocks do provide clues about the nature of early Earth
• Earliest signs of life are microbial, and microbes still constitute most of the world's biomass and genetic diversity