Young goats learn new and distinctive bleating 鈥渁ccents鈥� once they begin to socialise with other kids.
The discovery is a surprise because the sounds most mammals make were thought to be too primitive to allow subtle variations to emerge or be learned. The only known exceptions are humans, bats and cetaceans 鈥� although many birds, including songbirds, parrots and hummingbirds have legendary song-learning or mimicry abilities.
Now, goats have joined the club. 鈥淚t鈥檚 the first ungulate to show evidence of this,鈥� says of Queen Mary, University of London.
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McElligott and his colleague, , made the discovery using 23 newborn kids. To reduce the effect of genetics, all were born to the same father, but from several mothers, so the kids were a mixture of full siblings plus their half-brothers and sisters.
The researchers allowed the kids to stay close to their mothers, and recorded their bleats at the age of 1 week. Then, the 23 kids were split randomly into four separate 鈥済angs鈥� ranging from five to seven animals. When all the kids reached 5 weeks, their bleats were recorded again. 鈥淲e had about 10 to 15 calls per kid to analyse,鈥� says McElligott.
Some of the calls are clearly different to the human ear, but the full analysis picked out more subtle variations, based on 23 acoustic parameters. What emerged was that each kid gang had developed its own distinctive patois. 鈥淚t probably helps with group cohesion,鈥� says McElligott.
鈥淧eople presumed this didn鈥檛 exist in most mammals, but hopefully now, they鈥檒l check it out in others,鈥� says McElligott. 鈥淚t wouldn鈥檛 surprise me if it鈥檚 found in other ungulates and mammals.鈥�
of Duke University Medical Center in Durham, North Carolina, says the results fit with an idea he has developed with colleague Gustavo Arriaga, arguing that vocal learning is a feature of many species.
鈥淚 would call this an example of limited vocal learning,鈥� says Jarvis. 鈥淚t involves small modifications to innately specified learning, as opposed to complex vocal learning which would involve imitation of entirely novel sounds.鈥�
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