I came across this interesting article recently.
Linguists studying languages around the world find they are quite diverse in structure, but there are also common features called ‘universal patterns’. It’s possible there are cultural influences that lead to this or could it be biological in origin?
The ideal experiment is to expose babies to patterns and see what they are producing, but that’s difficult to interpret in humans. Most animals are actually born with the ability to produce vocalisations, but songbirds – like humans – learn during development.
The process is similar to how humans learn to speak: a bird hears an adult sing, memorises it, then starts babbling. It sounds terrible initially, as if you were squeaking a rubber duck, but with time and practice their vocalisations become more species typical. Not unlike human languages, there are common features in acoustic patterns across different populations of birds, but we don’t know whether they are cultural or routed in biology.
So to find out more, scientists raised zebra finches without song. When the eggs hatched mum and dad were left in the nest for less than a week. Only the males produce complex songs, so the father was removed and just the mother took care of the offspring. When the youngsters were able to feed themselves they were housed individually. At that point the scientists took five syllables common in zebra finch songs and presented those to them in every sequence possible – 120 different permutations – in equal proportions and in random order. In fact, all the acoustic patterns you can produce with those five syllables. This was done with about 50 birds.
It was found that there were consistent patterns that birds ended up producing as adults. For example, there’s what’s called a ‘distance call’, a long syllable that has a downward sweep. If they produced those syllables, they put it at the end of the phrases. These birds were bought from pet stores but, despite that, these were patterns also found in wild birds. That suggested that at least some biological component was present to produce similarities in acoustic patterning.
So, what has been learnt so far? Maybe the brain likes to hear particular patterns because that allows it to remember more clearly, or maybe there is something about the vocal apparatus that makes it easier to produce those patterns. Humans have a larynx or voice box and birds have a syrinx, but the general properties of breathing through a pipe that has a membrane is the same. The brain pathways involved in vocal learning in birds are similar in humans. What we can do in songbirds is probe those neural circuits, something that can’t yet be done humans. In the future this may help us develop further our understanding of the neuroscience of speech and language and how we might build mechanisms to aid humans with problems in this field.
Isn’t the voice fascinating!
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