Week8_answers - Biology 180 study questions-Week 8 1...

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Biology 180 study questions—Week 8 1. Researchers initially hypothesized that all human evolution was “anagenetic”--meaning that a single population had changed through time from the common ancestor of chimps and humans to Homo sapiens . What evidence suggested that this hypothesis was not correct? The existence of several hominin species in the same geographic regions at the same time. 2. What trends occurred over the past five million years of human evolution? For each trend, state a hypothesis for why the observed change might have been adaptive in the environment(s) occupied by our ancestors. Increased brain size: increased memory and learning ability used to manufacture tools and manage social interactions Smaller teeth and jaws: Improved ability to speak; relaxed selection for ability to process coarse foods because of tool and fire use Increased height: Improved ability to hunt and/or fight Reduced sexual size dimorphism: produced by relaxed sexual selection due to increased paternal care Increased cultural evolution: rapid spread of ideas relating to tool use, hunting or agricultural strategies, religious beliefs, political/social systems 3. If you make a logarithmic plot of overall body size versus brain size for mammals, the data points fall on a straight line. The data points for fossil and living humans, however, fall far above this line. What does this observation mean?
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Week8_answers - Biology 180 study questions-Week 8 1...

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