Is population or typological thinking more appropriate in classifying the following entities? (The answer is not certain in all cases, and they are as much topics to think about and discuss, as to provide final answers about.) (i) Chemical elements (such as atoms of carbon, hydrogen, gold, etc.); (ii) human cultures; (iii) biological species; (iv) human emotions (such as fear, anger, etc.); (v) mechanisms of transport (such as cars, walking, airplanes, and so on); and (vi) scientific theories (such as evolution, gravity, quantum theory, etc.).