EXPERIMENTATION (EMPIRICISM) Observe repeated, correlated physical phenomena/patterns “On Caribbean Islands with lizards, there are no spiders”īring other observed facts to bear “They use similar habitats” (could live together) “Lizards eat spiders” “Lizards and spiders eat other insects” “They disperse differently” (so they may have gotten to different islands by chance) Observe repeated, correlated physical phenomena/patterns “On Caribbean Islands with lizards, spiders are rare” GOAL: is this relationship causal? In fact, the homology is so good that lineages of eyeless flies lacking that hox gene can have the ability to grow eyes restored by adding the homologous gene from a mouse…and flies develop compound eyes with the mouse hox gene for eye development, even though mice have camera eyes… HOW COOL IS THAT!? coli, fruit fly, house mouse) illuminates the field of medicineĪnd the most dramatic examples of homology are in the hox genes, as well. This is why the use of model organisms (E. COMPARATIVE METHOD Why is this method so powerful in biology? Is there a REASON why different organisms might have similar structures and functions? Yes… common ancestry. COMPARATIVE METHOD Why is this method so powerful in biology? Is there a REASON why different organisms might have similar structures and functions?Ģ. Visual systems in molluscs: Half an eye (retina) CAN work…Ģ. COMPARATIVE METHOD The function of complex systems may be understood by comparing them with simpler systems (with fewer subsystems). How could a complex system like a camera eye, composed of mutually dependent parts, have evolved through a stepwise sequence? Half an eye (lens) can’t work…Ģ. Powerful Approach: living systems are very complex, so describing the STRUCTURE can give insights into FUNCTION. REDUCTIONISM Gaining an understanding of a system by describing its subsystems (components) ≠ “emergent properties” REDUCTIONISM Gaining an understanding of a system by describing its subsystems (components) Limitations: - What is studied: the physical world /universe - How it is studied (Method): empiricism “of the senses”, but not “common sense”… Limitations: - What is studied: the physical world /universe A medieval, Ptolemeic view of the universe The systematized knowledge of nature and the physical world.” Definition: Webster’s: “systematized knowledge derived from observation, study, and experimentation carried on in order to determine the nature or principles of what is being studied. Definition: Webster’s: “systematized knowledge derived from observation, study, and experimentation carried on in order to determine."- Presentation transcript:
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