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Three principle forms of natural selection: (a) stabilizing selection, (b) directional selection, an
This engraving by William Russell Birch shows Congress Hall (left), which was occupied by Congress f
These illustrations show Ellen Craft, a slave with and without a disguise. She dressed “as a disting
That politics was always a rough business is shown in this cartoon, which shows Lincoln, assisted by
Action! Children love to talk about the actions of adults and animals, which provides a natural way ...
Natural Causes of Climate Change