The Facts…. ► 99% of everything that has ever lived no longer exists on the Earth – it is extinct ► Some modern organisms look very similar to other unrelated organisms (ex. Ant-eaters & Echidnas) ► Some modern organisms look very similar to ancient organisms that are now extinct (ex. fossils) ► For centuries, people looked at these fossils and tried to EXPLAIN what they are, and what they mean What hypotheses could you propose for the diversity of life? What evidence could you gather? What do you ALREADY KNOW about inheritance?
“EVOLUTION” – what’s all the fuss about?! ► Theory = “a scientific explanation of natural phenomena, based on empirical evidence” A theory brings together all the research into a single cohesive, testable explanation ► Evolution = “change over time” A scientific explanation for the origin, diversity and continued change observed within living things Defined more specifically in Biology as “descent with modification” (ie. The things alive today are modified versions of their ancestors…just like you and me!) Physical traits are passed-on to offspring Some traits are beneficial, others aren’t The beneficial traits remain in the population, and become more common over time – THIS IS “EVOLUTION”…
► ALEXANDER OPARIN - FORMATION OF MACROMOLECULES WITHOUT OXYGEN ► STANLEY MILLER AND HAROLD UREY EXPERIMENT “Created” amino acids from simulated early Earth conditions… http://en.wikipedia.org/wiki/Image:Miller-Urey_experiment_en.pnghttp://en.wikipedia.org/wiki/Image:Miller-Urey_experiment_en.png creative commons copyright
8. Ultimately, ALL organisms on Earth are united into a single tree of life… Darwin’s original sketchbook drawing
Darwin’s Theory is supported by…. ARTIFICIAL SELECTION ► Nature provides variation but humans decide what traits are selected and passed on. ► Hybridization brings about new variations
Descent with Modification Darwin proposed that after long periods of time, offspring of ancient organisms spread out through the environment, and natural selection then results in organisms with traits that are very different from their ancestor Different structures Different niches Different habitats We call this Adaptive Radiation
Evidence of Evolution ► Fossil Records - fossils being discovered were evidence that the world was much older that once thought. 99% of species that once lived are now extinct!!!!!! Did you know???? Some fossils were very similar to modern day creatures
Fossils show history of life on Earth Relative Dating - The layering of rock can show which fossils are older.
Fossils show history of life on Earth Radioactive Dating -using the half-life of radioactive elements scientists can tell approx. how old a fossil is…
What Does The Fossil Record Tell Us About Evolution? ► Sedimentary rocks can be dated by studying the decay of radioactive isotopes they contain. ► In some cases, successive layers of rocks of different ages are so well-preserved that families of similar fossils can be traced through the layers, over several million years of history ► This apparent transition suggests a pattern of development, and allows scientists to infer changes from one form to another and construct a diagram called a Phylogenetic Tree…
Trilobite Evolution Phylogenetic trees show the evolutionary ancestry of organisms, based on their inferred relationships to ancestral species
The History Of Life ► The fossil record has allowed scientists to locate the “first appearance” of different organisms within rocks of a specific age ► The pattern of change & progression suggests that recent organisms might be modified forms of ancient organisms that previously existed
The Geological Timescale Based ONLY on the fossil evidence, it appears that the nature and diversity of life on our planet has changed dramatically throughout Earth’s history But HOW have these changes occurred? But HOW have these changes occurred?