Origin of Life Biogenesis – Principle that says all living things come from other living things We know this now… but it hasn’t always been that way Spontaneous Generation – Theory from the early 1600’s stating that living things could also arise from nonliving things (Example: Maggots appear on rotting meat) The debate was solved by several great experimenters!

Biogenesis vs. Spontaneous Generation Francesco Redi (1626-1697) Noticed adult flies producing ‘oval cases’ from which new flies eventually arose 1668 controlled experiment (supports biogenesis) Louis Pasteur (1822-1895) Different experiment, but same conclusion Modification of Lazzaro Spallanzani’s experiment (monitors microorganismal growth)

The FIRST ORGANIC COMPOUNDS Life comes from life, comes from life, comes from… ? Miller and Urey created an apparatus (1953) to mimic the early atmosphere of Earth as proposed by Oparin (1923) A mixture of methane, ammonia, hydrogen, and water vapor was energized, then condensed A ‘scum’ was extracted and found to contain AMINO ACIDS

Change over Time FACT: The planet Earth is extremely old 4.6 billion years ago – our planet was formed 3.9 billion years ago – oceans formed 3.5 billion years ago – we have evidence of life! FACT: The organisms that existed then are different from those that live today EVOLUTION – A scientific theory that says species change over time QUESTION: In science, when do we say that a hypothesis is proven? DEFINITION: Theory – the status of a hypothesis when it has been supported by a large amount of evidence

EVIDENCE for EVOLUTION The Fossil Record Structural Similarities Vestigial Structures Embryonic Development

THE FOSSIL RECORD FOSSILS CAN BE DATED: Relative Absolute A fossil is an imprint/trace of a long-dead organism (usually found in sedimentary rock) FOSSILS CAN BE DATED: Relative Molds found in lower layers of rock are older Absolute Radiometric dating (example: carbon-dating) THE FOSSIL RECORD (a time scale for the entire history of life on our planet) indicates that over time, organisms of increasing complexity appeared on earth

Radiocarbon Dating Laboratory

Structural Similarities HOMOLOGOUS STRUCTURES Anatomical features found in different species that show the same relative structure, indicating common ancestry EXAMPLE: Forearms in the bat, penguin, human, and alligator ANALOGOUS STRUCTURES Anatomical features found in different species that serve similar functions but have different structures EXAMPLE: Wings of moths and wings of birds

VESTIGIAL STRUCTURES EXAMPLES: - Human tailbone An anatomical feature that is present in an organism, but (now) serves no useful purpose EXAMPLES: - Human tailbone - Pelvic bones in whales

EMBRYONIC DEVELOPMENT Showing physical similarities during embryonic development (between conception and birth) These similarities usually disappear before birth EXAMPLE: All vertebrates possess a tail and gill slits at some time during development

Theories of EVOLUTION Jean Baptiste de Lamarck (1774-1829) French Scientist 1809 – “the inheritance of acquired characteristics” * NO EVIDENCE * Lamarck put forward the idea that traits would be changed/modified based on a conscious use or disuse, and that this modified trait would be passed on - Slithering salamander - Neck stretching giraffes

Theories of EVOLUTION Charles Darwin (1809-1882) British Scientist Theory of NATURAL SELECTION Explained in his 1859 book… THE ORIGIN OF SPECIES * Independently proposed at the same time by Alfred Wallace (1823-1913)* 1831-1836 H.M.S. Beagle voyage Mapping and collecting expedition Studied finches of the Galapagos Islands (off the coast of South America)

The Finches of the Galapagos Darwin saw 13 separate, yet similar species of finches The species only differed in their beak shapes and the types of food they ate Darwin believed that a single finch species coming from South America could have inhabited the islands, diverging into the 13 different species

NATURAL SELECTION Resources are limited A struggle/competition for survival results There is variation within a species (some individuals have traits better suited for survival) Those individuals most FIT are able to… survive and reproduce SURVIVAL OF THE FITTEST Favorable traits are passed down through the generations Over time, a population adapts to the environment