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Although Charles Darwin and others posited that multiple species could evolve from a single common ancestor , the mechanism by which this occurred was not understood , creating the " species problem " .
 person: Charles Darwin
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
 Entities: Charles Darwin 
Answer:
 person: Charles Darwin