Periodicity in Nature 2

• Classifying period phenomena
  • By the kind of characterizing variable (visual, auditory, economic, etc.)
  • By the period (or frequency)
    • Short (violin string)
    • Medium (juggling, music, language)
    • Long (sleep cycle, tides)
  • By continuity
    • Continuous (pendulum, ocean waves)
    • Discrete (insect chirp, drum beat)
  • By regularity
    • More regular (rotation of earth, music)
    • Less regular (language, breathing, fashion)
  • By origin
    • Physical law
    • Unconscious biological process
    • Conscious, learned biological process
• Periodicity in animals and the environment
  • Synchronization of periodic processes with each other
    • Animals with the environment
    • Animals with each other
  • Reasons for biological periodicity and synchronization
    • The environment has periodicity in it, so animals should take advantage of it.
    • A relatively constant flow of some substance (for example, blood) may be necessary, but a natural way to release the substance may be in discrete amounts.
    • Some substances or activities (for example, sleep) are required periodically.
    • Physical systems are naturally periodic; the bodies of animals are physical systems.
    • When conscious behaviors are scheduled periodically, they are easier to remember.
    • Periodic phenomena which are in direct or indirect contact with each other naturally adapt to one another.
    • Groups of animals may function more efficiently if they synchronize some of their periodic processes.
    • Social animals may foster group cohesion by synchronizing some of their behaviors.