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Johansson, Working backwards from modern language to proto-grammar, 2006	::	1
Loula,Gudwin,El-Hani,Queiroz, Emergence of self-organized symbol-based communication in artificial creatures, xxxx	::
Ribeiro,Loula,Araujo,Gudwin,Queiroz, Symbols are not uniquely human, 2007	::	1