Is language first and foremost an artifact of culture? Or is it largely determined by human biology? This issue has been argued back and forth for a couple of centuries with no clear resolution in sight. Guy Deutscher’s 2005 book “The Unfolding of Language” placed him firmly in the pro-culture camp. Now, in his new book, “Through the Language Glass,” he examines some idiosyncratic aspects of particular languages that, in his opinion, cast further doubt on biologically based theories of language.