Humans' Speech May Have Evolved from Birds' Songs
Charles Darwin posed the hypothesis first. In The Descent of Man, he wrote that human languages may have originated with songs, which "might have given rise to words expressive of various complex emotions... The sounds uttered by birds offer in several respects the nearest analogy to language."
Now, linguists from the Massachusetts Institute of Technology believe that the naturalist was on the right path. In a recent paper, they suggest that human language is the grafting of two forms of communication that exist in the animal kingdom, which manifest in two primary ways. Birds use the "expression" layer of communication, which consists of the changeable composition of sentences. For example, birds often loop the same melody, which is reminiscent of humans' use of the same words and expressions over and over. The other layer is "lexical", which pertains to the overall meaning of a sentence or phrase. This can be seen in primates, for example, who use certain calls to alert their companions of the presence of a predator; in humans, it can be seen when we communicate basic information.
About 50,000 to 80,000 years ago, humans combined these two forms of communication to create language, Shigeru Miyagawa, a professor of linguistics at MIT, proposes.
"When something new evolves, it is often built out of old parts," Robert Berwick, a professor of computational linguistics at MIT, said in a statement. "We see this over and over again in evolution. Old structures can change just a little bit, and acquire radically new functions."
As Darwin proposed, the linguists theorize that humans first developed the ability to sing. This ability was followed by a capacity to develop the "lexical" layer. They point out that humans and birds both have parallels in the periods of their lives during which they are best suited to learn a language. The portion of the brain devoted to language is similar in both birds and humans as well.
If the researchers' theory is correct, researchers would be able to test the theory on animals today - like bees, primates and birds.
The study was published in the journal Frontiers in Psychology.