classification

• Classification


  A way to group and organise different species on Earth
• Ancestors often classified species based on what they looked like
• Simple names for species don't tell us much about how related they are
• Linnaean system


  A classification system proposed by Carl Linnaeus in the 1700s that groups species together based on their characteristics and bone structures
• Levels of the Linnaean system

  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Binomial naming system


  A system where species are named by their genus and species names, written in italics with only the first letter of the genus capitalised
• The Linnaean system is still used today, but new models of classification have been proposed and combined with it
• Three domain system


  A classification system proposed by Carl Woese in the 1990s that introduced three new categories called domains, placed above kingdoms: Eukaryota, Bacteria, and Archaea
• Bacteria and Archaea are both prokaryotic organisms, but Archaea are a different type found in extreme conditions
• Evolutionary trees


  Diagrams that show the evolutionary relationships between different species or groups by linking common ancestors
• Evolutionary trees can look quite different, but the main thing is that whenever a line splits, it's because a common ancestor is splitting into two different species
• Scientists compare the structure and DNA of different species, including fossil records, to learn about their evolutionary relationships