 This process "would have created new words and deployed old words in new contexts, further weakening the uncoupling of words from situations, from current occurrence—even from fitness", and thus allowing for the creation of symbolic language.In "The Symbolic Species", Terrence Deacon argues that the emanation of symbolic capacities unique to language was a critical factor in the evolution of the human brain, and that these symbolic capacities are vital to differentiating animal from human forms of communication, processes of learning, and brain anatomy.