154798
Archaeologist Barry Cunliffe believes that population increase still played a role and has stated " [ the forts ] provided defensive possibilities for the community at those times when the stress [ of an increasing population ] burst out into open warfare .
 Barry Cunliffe
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Barry Cunliffe