Seemingly haphazard sounds made by many social animals (like chicken cluck) are known as contact calls. Contact calls are very different from many other types of calls (for example, alarm calls), as contact calls are not a specific signal, designed to communicate some specific information. It is rather a mixture of various sounds, accompanying the group's everyday business (for example, foraging). Contact calls are used to maintain audio contact with the members of the group. Some social animal species communicate the signal of potential danger by stopping contact calls, without the use of alarm calls. Charles Darwin

Charles Darwin

Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 wrote about this in relation with wild horse and cattle.

Humming as contact calls

Joseph Jordania

Joseph Jordania

Joseph Jordania is an Australian-Georgian ethnomusicologist and evolutionary musicologist. In some early publications his name was spelled as Zhordania...

 suggested that human humming could have played a function of contact calls in early human ancestors. According to his suggestion, humans find distressing being in full silence (which is the sign of danger for them) that's why humans hum, whistle, talk to themselves, have TV and radio on sometimes without watching or listening to them.

See also

• Humming
• Singing
  Singing
  Singing is the act of producing musical sounds with the voice, and augments regular speech by the use of both tonality and rhythm. One who sings is called a singer or vocalist. Singers perform music known as songs that can be sung either with or without accompaniment by musical instruments...
  
  
• Animal communication
  Animal communication
  Animal communication is any behavior on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication, is sometimes called Zoosemiotics has played an important part in the...
  
  
• Whistling
  Whistling
  Human whistling is the production of sound by means of carefully controlling a stream of air flowing through a small hole. Whistling can be achieved by creating a small opening with one's lips and then blowing or sucking air through the hole...
  
  
• Silence
  Silence
  Silence is the relative or total lack of audible sound. By analogy, the word silence may also refer to any absence of communication, even in media other than speech....