Scientists have found that birds from different continents use the same alarm call - a discovery sheds light on the evolution of language

An international team of researchers has discovered that birds separated by vast geographic distances and millions of years of evolution use very similar learned vocal signaling to warn of parasitic birds near their nests. The discovery is the first to document animal vocalizations that combine innate and learned components, which could explain how communication systems have evolved from instinctive sounds to learned signals, including human language.

The study was published in the journal Nature Ecology & Evolution. The work was led by scientists from Cornell University and the Doñana Biological Station in Seville, Spain. This is one of the largest and most comprehensive studies of nest parasites. The authors studied more than 20 different bird species on four continents that produce nearly identical "whining" vocalizations when they detect a parasitic bird in their territory.

Nest parasitism occurs when birds like cuckoos lay eggs in the nests of other species, forcing the hosts to raise another's offspring, often at the expense of their own chicks. Researchers were interested in why birds from Australia, China and Zambia use the same call to indicate parasites, despite the lack of contact with each other. It turned out that species that produce such a signal, as a rule, live in areas with complex networks of interactions between nest parasites and their hosts.

When a bird hears a warning cry, it instinctively flies to that spot to investigate the situation. It is at this point, the researchers say, that birds begin to remember such calls and subsequently reproduce them for the same reason - a process that Damian Blasi, study co-author and linguist at the University of Pompeu Fabra in Spain, calls social transmission.

William Feeney, an evolutionary ecologist at the Doñana Biological Station and one of the leaders of the study, noted that this call represents an intermediate point between the instinctive vocalizations of animals and fully learned vocal units, like human words. Kennerley added that the evolution of whining vocalizations influences patterns of cooperative behavior between birds around the world, since communication about how and when to cooperate is critical when working together to expel parasites.

Feeney emphasized the uniqueness of the discovery:

“For the first time, we have documented vocalizations that have both learned and innate components, potentially showing how learned signals may have evolved from innate ones in a manner first proposed by Charles Darwin.”

The authors suggest that learned communication systems, like human language, may have evolved through the gradual integration of instinctive and learned elements.