Presentation on theme: "How Scientists Determined that Living Things Change Over Time"— Presentation transcript:
1 How Scientists Determined that Living Things Change Over Time 4/6/2017Evidence of EvolutionHow Scientists Determined that Living Things Change Over TimeVideo #3 – “How Do We Know Evolution Happens?”Printed off Blackboard
2 Fossil Record Fossil = remains of any living things or their prints Fossils include:BonesCasts or moldsImpressionsTop left – impression of a worm; center – cast of a mollusk; right – humerus bone of a turtle“Becoming a Fossil” – 2:34
3 Comparative Anatomy- body parts Comparing the structures of organismsSimilarities indicate evolutionary relationships.
4 Comparative Anatomy, cont’d Homologous structures – have similar insidesthese have a similar structures and may or may not have a similar functionindicate common ancestry:
5 Comparative Anatomy, cont’d Analagous structures – have similar outsidesthese have a different structure but similar functionindicate common environmental pressures:
6 Comparative Anatomy, cont’d Vestigial structures – seem to have little or no importance in modern organismsIndicates that the structures were useful (a long time ago)The pelvis (and femur) of a whale is a vestigial structure;it suggests that ancestors of whales had four legsHumans also have vestigial structuresTonsils & AppendixWhale Evolution – 5:09
7 Comparative Embryology Closely related organisms appear to go through similar stages as embryos“Common Past, Different Paths” – 1:36
8 Comparative Biochemistry / Molecular Biology There is a common genetic code DNAAnalyzing and comparing DNA sequences and proteins can show a relationship among species.“The Common Genetic Code” – 4:20
9 The genetic similarities between humans and primates indicates that we share a common ancestor – NOT that humans came from apes!Humans are more similar (genetically) to chimpanzees than to gorillas or orangutans. This suggests that humans and chimpanzees split / branched off from our common ancestor more recently than gorillas and orangutans.“Human Chromosome 2” – 3:27
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