Overview:
In science, proving something as fact is sometimes possible – the evidence points unshakably to one answer. Further experiments and evidence support that answer over and over again without fail (for example, the earth is round).  Other times, as in the case of the origin of HIV, arriving at a right clear-cut answer is very difficult.  Conflicting, incomplete, or missing evidence, the lack of precise equipment, or political obstacles can limit the ability to arrive at a conclusive answer.  All we can do is to continue to hypothesize, investigate, and engage.  Thus, it is crucial to have as many perspectives and voices as possible and to engage in dialogue.  Whether we are scientists, citizens providing funding for science, voters advocating for science, or the public consuming findings from science, we have a role to play.  Now that you have examined each of the three theories—Natural Transfer, Serial Passage, and OPV— you can compare the three side-by-side.

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Capstone Lesson 17-19 Theories of Origin (Grayscale)
Capstone Lesson 17-19 Theories of Origin (Color)
Capstone Lesson 17-19 Theories of Origin (Color Ink Saving)
Teacher Reference Reading 1
Teacher Reference Reading 2