When did language begin? The question is not an easy one to answer. There are no records of the event. "Languages don't leave fossils," notes the Linguistic Society of America, "and fossil skulls only tell us the overall shape and size of hominid brains, not what the brains could do." The scant evidence from evolutionary biology does not tell us when early humans first began to use language, only that they could 100,000 years or so ago.

However, the question also depends on what we mean by language. Before the linguistic technologies of grammar and syntax, hominids, like other mammals today and a good number of non-mammals too, had a wordless language that communicated more directly, and more honestly, than any of the thousands of ways to string syllables into sentences.

That language still exists, of course, and those who understand it know when someone is afraid, relieved, frustrated, angry, confused, surprised, embarrassed, or awed, no matter what that someone says. It is a language of feeling-of sighs, grunts, rumbles, moans, whistles, sniffs, laughs, sobs, and so forth. Researchers call them "vocal bursts" and as any long-suffering married couple can tell you, they communicate a whole range of specific feelings.

"Emotional expressions color our social interactions with spirited declarations of our inner feeling that are difficult to fake, and that our friends, co-workers and loved ones rely on to decipher our true commitments." A study was devised to test the range of emotion vocal bursts can carry.