It is well known that human speech can provide listeners with simultaneous information about a person's emotions and objects in the environment. Past research has shown that animal vocalizations can do the same, but little is known about the development of the features that encode such information. Observing wild, but habituated, meerkats (Suricata suricatta) in the Kalahari Desert, researchers from the University of Zrich have shown that a youngster's understanding about the urgency of a threatening situation develops earlier than their understanding about the type of threat faced (in the June issue of The American Naturalist).
Meerkat alarm calls are previously known to encode information about both the type of approaching predator (for example, eagle or jackal) and the urgency of the threat (for example, close or far). This information enables listeners to adjust their response to the particular threat and to decide whether to respond immediately. Dr. Linda Holln and Prof. Marta Manser have now established how these processes develop in young animals. By analyzing alarm calls from both young and adult individuals, which they recorded while walking within a few feet of the animals, the researchers found that the link between acoustic features and threat urgency develops earlier in life than the link between acoustic features and threat type. They argue that this suggests a more basic, hard-wired link between acoustics and "emotion" than the link between acoustics and external objects. "This would parallel the developmental pattern in young children," says Dr. Holln.