Language

On the continuing topic of what makes us unique, separate from the rest of the animal kingdom, special... proposals have been made and knocked down -- bipedal upright walking, tool use, social grouping, language -- all also practiced by different species. I favor the idea that we are the only ones who ask The Question; we ponder our existence and place. And, to ponder, we need sophisticated language.

According to the article, "Can we Talk?" by Annette Lessmoellmann in the October/November 2006 Scientific American Mind (p.44-49):

"The trait that makes human language different [from other animal language] is the complexity of sentence structures that we employ." ... "The thinking goes that no other animal... can create nested sentences such as 'The woman, whose dress, which was not unattractive, and rustled when she walked, sat down next to me.' ... In short, relative clauses are a human prerogative." ...

"When our ancestors' brains developed the ability to process nested structures, they were suddenly able to explore, improve and diversify their communication in complex new ways. It was as if they discovered a music or a grammatical rhythm in the world to which every other creature was tone-deaf. And ultimately that may have given humans a great deal to talk about."

Indeed.