What is “evolution”?• Change in the gene pool of a population from generation to generation by such processes as mutation, artificial/natural selection, and genetic drift.
Timeline of Theory 1785 James Huttonpostulated that the earth was formed by an 1830 Charles ancient Lyell published 1858 Alfredprogression of evidence pushing Russell Wallacenatural events, the age of earth publishes similar including back several theory of erosion, million years. evolution.disruption, and uplift. Early 1800’s George Cuvier suggested that 1838 Charles the earth was Darwin starts to 6,000 years old- theorize on based on his evolution. calculations.
Mutation• A sudden departure from the parent type in one or more heritable characteristics, caused by a change in a gene or a chromosome.
Natural Selection• The process where organisms better adapted to their environment tend to survive and produce more offspring.
Artificial SelectionThe practice of choosing individuals from apopulation for reproduction, usually becausethese individuals possess one or moredesirable traits
Genetic Drift• Process that causes allele frequencies to fluctuate unpredictably from one generation to the next.
Charles Darwinwas a British scientist wholaid the foundations of thetheory of evolution andtransformed the way wethink about the naturalworld.Wrote the book Origin ofSpecies which establishedevolution by commondescent as the dominantscientific explanation ofdiversification in nature.
Where did he get this theory?• A man by the name John Henslow asked Darwin to accompany him (Was in need of a naturalist)• Went on a voyage on the ship H.M.S Beagle• Which was a five year trip all around the world.• Found evidence to propose a revolutionary hypothesis about how life changes over time• Evidence included fossils, invertebrates, vertebrates and closely related species such as plankton and turtles.
H.M.S Beagle Route
The Voyage• Darwin collected specimens from each place they stopped.• Included shells, animals, fish, plants and fossils.• Compared specimens of different origins and realized they had similar structures.
The Galapagos Islands• Darwin was particularly fascinated by this area.• Low, smaller islands are: -hot and dry -very little vegetation• Higher, larger islands have: -a variety of plants and animals -more rainfall• Focused on the native tortoises and marine iguanas.• Tortoises’ shells directly reflected which island they inhabited.
Patterns of Diversity• Darwin realized many places have similar ecosystems, but different Glyptodon - lived 2,500,00 to 10,000 years ago inhabitants.• He studied the correlation between fossils found and the organisms alive today. Armadillo - presently lives in the Americas
Thought Process• He pondered why some plants and animals are extinct; whilst others are emerging from currently unknown origins.• Theorized that not all of the species were dying but actually adapting and evolving.
Who helped Darwin?James Hutton:• 1795 Theory of Geological change – Forces change earth’s surface shape – Changes are slow – Earth much older than thousands of years
Who helped Darwin?Charles Lyell:• Book: Principles of Geography- Geographical features can be built up or torn down Darwin thought if earth changed over time, what about life?
Who helped Darwin?Thomas Malthus 19th century English economist• If population grew (more Babies born than die) – Insufficient living space – Food runs out – Darwin applied this theory to animals
Evolution via Natural Selection• “Survival of the Fittest”• Some individuals are better suited for the environment.• Members of each species have to compete for food, water and shelter.
Descent• Two types – Descent with modification- Each living organism has descended with changes from other species over time. – Common Descent- Derived from common ancestors.
Evidence of Evolution• The Fossil Record – Where fossilized artifacts are embedded into the Earth’s stratum
Evidence of Evolution• Geographic Distribution of Living Species – When the world had one main landmass (Pangaea) and the species migrated to specific areas as the landmass shifted apart.
Evidence of Evolution• Homologous Body Structures – Body parts that are similar because the said species share a common ancestor.
Evidence of Evolution• Similarities in Early Development – Various species have similar structures when in infancy. Fish Reptile Bird Human
Evolution of the Skull Homo sapiens Homo sapiensAustralopithecus( Homo erectus neanderthalensis sapiens man-ape) (java man) (neanderthal man) (L’homme sage) Between 2 and 750,000 years ago Between 40,000 years 3 million years 100,000 and ago to the ago 400,000 years present ago