19800
Subsequent eastward stepping - stone colonization within the Canarian Archipelago culminated in a very recent late ( possibly even post - ) Pleistocene back - colonization from the Canary Islands to North Africa .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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