Barking dogs might be better communicators than we thought, according to a new study.
Computer software can distinguish individual dogs by their barks, and also suggests that certain barks act as a 鈥渦niversal language鈥�, carrying information about the dog鈥檚 mind-set that is readily understood by their fellow pooches.
Csaba Moln谩r and his colleagues at in Budapest, Hungary, recorded 14 Hungarian sheepdogs barking in a range of situations: when approached by a stranger, during play, during a fight, and when the dog was alone.
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Then they fed the sound recordings into an artificial neural network developed by a team led by at the Ecole Polytechnique F茅d茅rale de Lausanne in Switzerland.
The artificial neural network identified key audio features of each bark and Moln谩r鈥檚 team found that the computer software could identify the situation in which a bark was recorded.
Varied accuracy
The accuracy of the software varied, however 鈥� while it correctly identified a dog barking at a stranger in 63% of cases, it correctly identified a bark recorded during play just 6% of the time.
The software also varied in its ability to identify individual dogs, depending on the context in which the bark was recorded.
When played samples of dogs barking during play, the software could correctly identify individuals 60% of the time, but it struggled to distinguish between different dogs barking at a stranger 鈥� it could do this only 30% of the time.
The results show that dog barks carry a wealth of information, says Moln谩r. 鈥淚n the past, scientists thought that dog barks originated as a by-product of domestication and so have no communicative role,鈥� he says. 鈥淏ut we have shown there are contextual differences.鈥�
Human selection
Moln谩r thinks that selection by humans could explain why an artificial neural network is better at recognising that a dog is fighting than playing. Domestic dogs have always been used for their vigilance, and so it may be important for humans to quickly identify when a dog is barking at a stranger.
鈥淚n this context, every dog barks singularly,鈥� says Moln谩r. 鈥淏ut in a play situation, there has been no strict selection for creating a uniform bark among dogs, so each has its own individual style.鈥�
鈥淭he idea sounds totally cool,鈥� says at Duke University in Durham, North Carolina, US. 鈥淭his is animal behaviour research at its best. You see a pattern that no one else knew was there because we can鈥檛 hear the difference ourselves.鈥�
鈥淚t鈥檚 interesting that the domestic dog鈥檚 communication may be more flexible than was formerly thought,鈥� adds of the Max Planck Institute, Leipzig, Germany.
Learned patterns?
She says there are other possible explanations for Moln谩r鈥檚 results, however.
鈥淚n play situations鈥� she says, 鈥渄ogs have many opportunities to learn something about the correlation between their vocalizations and the human鈥檚 behaviour: 鈥榳hich variation in my bark elicits what type of behaviour in the human?'鈥�
If this is the case, it might be that it is the 鈥減lay鈥� barks that have evolved with time rather than the 鈥渇ight鈥� ones. 鈥淚n fight situations, the dog barks aggressively and the human runs away, end of story,鈥� she adds, which might explain why these barks have changed little.
Either way, Hare thinks the new study shows the importance of research into dog behaviour. 鈥淧eople used to say dogs are really boring because they were artificially created by humans,鈥� he says. 鈥淏ut actually that鈥檚 exactly why they鈥檙e really cool.鈥�
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