Songbirds can sing beautifully, but parrots can also, for example, learn to pronounce the words of human speech.
Now, American scientists have discovered that the brain mechanisms that organize the vocalization of songbirds and parrots are fundamentally different.
In the history of evolution, the parrot group and the subgroup of songbirds belonging to the colored group diverged about 50 million years ago.
Many songbirds, such as the most studied of all the zebra-winged birds, learn their song at a young age by imitating other birds, and their song does not change much thereafter.
Parrots, on the other hand, constantly learn new vocalizations and can flexibly vary already learned vocalizations. In terms of such abilities, parrots are already similar to us humans, who can learn new words and then seamlessly combine them with previously learned ones.
Both groups of birds, parrots and songbirds, have a neuronal structure in the forebrain that is responsible for learning and producing vocalizations.
Both have, so to speak, anterior and posterior neural pathways in these structures. The functions of these masticatory pathways have been studied extensively in songbirds, but much less so in parrots.
Zhilei Zhao of Cornell University in the US and his colleagues have now examined what happens when a parrot temporarily shuts down one or the other of these neural pathways.
It turns out that, unlike songbirds, which can continue singing even when one of two neural pathways is closed, parrots need both pathways to be active. As soon as a lane is closed, the parrot becomes completely silent.
The experiment demonstrated that it was the anterior neural pathway that the parrots needed to hear learned vocalizations.
Zhao and coauthors conclude in the journal Current Biology that the function of vocal structures has evolved very differently over time in the brains of parrots and songbirds, even though the structures appear anatomically the same.
In other words, in order to constantly learn new vocalizations and flexibly perform the learned vocalizations, just like humans, parrots had to develop a brain mechanism that works completely differently.
The study by Zhao and his colleagues could also be useful for understanding the evolutionary basis of human language.
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2023-12-11 09:43:00
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