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CREATIONISM VS. EVOLUTION A SPECTRUM OF BELIEFS CREATIONISTS LITERALIST PROGRESSIVE THEIST ATHEISTS • Old Universe • Days in Bible should not be taken literally • Evolution did occur • Life was created by a supernatural being • Young universe • Literal days in Bible • No supernatural beliefs • All life evolved from one organism
Origin of Life • Introduction • Prior to the seventeenth century, scientists believed in a process called spontaneous generation, or the idea that living organisms could spontaneously arise from nonliving things. • Why? • Maggots appeared on rotting meat • Fish lived in ponds that were dry the year before
Origin of Life • In an attempt to learn more about spontaneous generation, scientists designed controlled experiments. • BUT…these experiments actually disproved spontaneous generation and proved a theory called biogenesis, or the idea that all living things arise from other living things.
Origin of Life • Experiments Supporting Biogenesis • 1. Redi’s Experiment • 2. Spallanzani’s Experiment • 3. Pasteur’s Experiment
Origin of Life • So…all living things must come from other living things. But, where did the first living things come from? 1. The Miller-Urey Experiment
Earth’s History • A. Introduction • Scientists estimate that the Earth is more than 4 billion years old. How did they arrive at this number? • B. Relative Dating Observing layers of rock in order to determine relative age (stratification). Ex: Which rock layer is the oldest? If fossils are found in these layers, the approximate age can be determined.
Earth’s History • C. Absolute Dating Determining an “exact” age through Radioactive Dating. • 1. Certain molecules—through collisions in the atmosphere—can become unstable, or radioactive. • 2. Let’s look at carbon, for example: • Carbon-12 (normal, 6 protons/6 neutrons) • Carbon-14 (radioactive, 6 protons/8 neutrons) • (These two molecules are considered isotopes, or molecules with the same number of protons but a different number of neutrons)
Through photosynthesis, plants take in carbon (a constant ratio of C-12 to C-14). So, anything that eats plants also consumes carbon.
When an organism dies, no more carbon is consumed. • Over time, the amount of C-12 stays constant. C-14 begins to decay into N-14.
By comparing the ratio of C-12 to C-14, the approximate age of a fossil can be determined. • Half-life the amount of time required for half of a material to decay. The half-life of carbon is 5,730 years. • Example: Assume, for simplicity’s sake, that C-12 and C-14 are found in a 1:1 ratio (instead of 1:1,000,000,000,000). A paleontologist finds a fossil containing 80g of C-12 and 40g of C-14. Since there were originally equal amounts of C-12 and C-14… • What percent of the C-14 sample has decayed? • So, what is the age of the sample?
Half-Life #2 25% Carbon-14 100% Carbon-12 Half-Life #1 50% Carbon-14 100% Carbon-12 0% Carbon-14 100% Carbon-12 100% Carbon-14 100% Carbon-12
III. The Fossil Record • Fossils • What? The remains or traces of a once-living organism. Formed by hard body parts like shell, bone, teeth, stems. 2. Where? Most often found in sedimentary rock (sometimes metamorphic).
III. The Fossil Record • Fossils • 3. How? Mold An imprint in rock in the shape of an organism. (Ex: the mold made for braces) Cast A mold is filled with minerals leaving a rock-like model. (Ex: pouring plaster into a footprint) Others Preservation (ice, amber, tar) Hard minerals replace soft tissue (petrified wood) Living Fossils The coelocanth, a deep water fish with fin-like legs The fossil record shows that the complexity of life has increased over time…