Evolution

• The materials are compiled from different sources
• Biological evolution is any genetic change in a population that is inherited over several generations
• Hypothesis


  A suggested explanation for an observable phenomenon or proposal that predicts a possible outcome
• Theory


  An explanation for something which is reasonable or scientifically acceptable, but which has not yet been proved to be true
• Theory of evolution


  Regarded as a scientific theory since various hypotheses relating to evolution, have been tested and verified over time
• Micro-evolution


  Small changes that take place within a species to adapt to survive
• Macro-evolution


  Large changes in many species that take place over a long period of time
• Fossil


  The imprint, traces or preserved remains of an organism that once lived
• Fossilisation


  The process that took place to produce the fossil over a period of time
• Anthropology


  The study of the human race, including the different belief systems, customs and social habits
• Palaeontology


  The study of the earliest known periods of human existence, e.g.: the Stone Age
• Archaeology


  The study of ancient times by examining the buried remains of buildings, tools, animal and plant fossil remains found in rock strata
• Archaeologist


  A scientist that digs up, studies and traces fossil remains in rock strata. Archaeologists use carbon dating to determine when the animals and plants lived
• Biodiversity


  The variety of different plant and animal species found on earth where diversity is the result of change over time
• Natural selection


  The process of change over time, that takes place in species
• Species


  A group of organisms that are similar in appearance, share the same DNA sequences, perform the same mating rituals and interbreed to produce viable offspring
• Population

  A group of organisms of different ages, that belong to the same species, live in the same area and interbreed
• Variation


  Small changes that will assist an organism where phenotypic variation (physical appearance) is as a direct result of genetic variation
• Continuous variation


  The variation of a trait in a population, where the trait ranges continuously from one extreme to another preventing the subdivision into distinct classes
• Discontinuous variation


  The variation of a trait in a population that can be ascribed to two or more distinct forms
• Artificial selection


  The selective breeding of plants and animals where specific traits are modified, to satisfy human needs
• Speciation


  The evolutionary process by which new biological species arise, due to the splitting of the lineage
• Genetic diversity


  The level of biodiversity and refers to the total number of genetic characteristics in the genetic makeup of a species
• Genetic divergence


  The process of one species diverging over time, into two or more species where genetic characteristics are passed from one generation to the next
• Extinction


  All the individuals of a species die and are eliminated permanently because they are unable to adapt to survive
• Theories of human evolution are based on research and scientific evidence that support the concept of continual change
• Sources of evidence for theories of human evolution

  • Geology
  • Anatomy
  • Embryology
  • Genetics
  • Physiology

  
• Further lines of evidence for theories of human evolution

  • Fossil records
  • Modification of descent
  • Biogeography
  • Genetics

  
• Fossil evidence


  • The first record of living material preserved as a fossil, is from the Palaeozoic era (540 million years ago)
• Genetic evidence


  • Organisms are closely related and are likely to have a common ancestor if they have: Identical DNA structure, Similar sequence of genes, Similar portions of DNA with no functions
• Modifications by descent


  • Similarities in the formation of body parts or organs due to a common evolutionary origin, e.g. the structure of the pentadactyl limb in seals, bats and humans
• Cultural evidence


  • Similarities and differences between humans and African apes shown by studies of tools, weapons, and language

  
• Biogeography


  The study of the distributions of organisms in space and time, focusing on ecological or historical factors
• Sources of variation


  • Crossing over in Prophase I of meiosis
  • Random arrangement of chromosomes in metaphase
  • Random fertilisation
  • Random mating
  • Mutation
• Continuous variation


  Variation within a population in which a graded series of intermediate phenotypes falls between the extremes
• Discontinuous variation


  Variation where individuals fall into a number of distinct classes or categories, based on features that cannot be measured across a complete range
• Ideas about origins


  • Lamarckism
  • Darwinism
  • Punctuated Equilibrium
• Lamarckism


  • Proposed by Jean Batiste de Lamarck, based on 'use and disuse' and 'inheritance of acquired characteristics'
• Darwinism


  • Proposed by Charles Darwin, based on natural selection and evolution by small, gradual changes over many generations
• Punctuated Equilibrium


  • Explains evolution involves long periods of equilibrium alternating with short periods of rapid change and speciation