A toehold to trace the origins of vocal communication, says S.Ananthanarayanan.

While many would consider the capacity for speech as exclusively human, there is evidence of vocal communication in many species. Whales, dolphins, elephant herds are well known examples. The case of songbirds goes further, where rhythm and fixed patterns of tones, and even rudimentary grammar have been noted. While animal parallels of speech do not compare with human ability, the study of animal vocalisation, with its simplicity, and the possibility of mildly invasive experimenting, could help understand the evolution of human speech.

Suriani Surbakti, Heidi G. Parker, James K. McIntyre, Hendra K. Maury, Kylie M. Cairns, Meagan Selvig, Margaretha Pangau-Adam, Apolo Safonpo, Leonardo Numberi, Dirk Y. P. Runtuboi, Brian W. Davis, and Elaine A. Ostrander, from universities and institutes in Indonesia, Sydney in Australia, Göttingen in Germany and Maryland, Florida and Texas, in the USA, report in the journal, Proceedings of the National Academy of Sciences, a discovery that a species of wild dog, which displays the facility of vocalising with near musical quality, feared extinct, is still to be found. That specimens of this rare breed could be there for study holds out a promise of understanding the features that made it possible for humans to develop the ability to speak and sing. And from there, possibly ways to deal with vocal or speech disorders or difficulty in processing sounds.

A well-known instance of directed vocalisation in animals is seen in the simple whistles of dolphins. The pattern is variations of the pitch, which are heard and remembered by other dolphins, as the identity of individual dolphins. The whistles were studied with the help of a modern, mathematical coding of musical compositions of humans, a method that has helped computers search for instances of plagiarism or copy, over the Internet.

The method relies on patterns of rise and fall of pitch, along the melody of a piece of music. The coding avoids complexities, like actual pitch, or loudness, and the process, which is known as Parson's Code, consists of only the sequence of the pitch rising, falling or staying unchanged. The picture shows the notes that appear in the song, ‘Twinkle, twinkle, little star.’ The notes are shown in the Indian notation and in western staff notation, and, in the Parson's code, the rising, falling or steady pitch is shown, as 'u' for rise, 'd' for fall and as 'r' when unchanged:

The code is not a way to record or reproduce a tune, but the code turns out to be unique and works as a signature for most melodies. Using this code to mark the whistles of dolphins, scientists were able to identify the signals sent out by each one and they found that the whistles of individual dolphins were unique - they identified the dolphin that made it. As the whistles thus carry information, it is believed that there are other messages that they convey.

The study of birdsong is replete with patterns. It has even been shown that a particular part of the brain is affected when a familiar pattern of birdsong being heard is changed. Injury to this portion of the brain has been found to affect song recognition in canaries and the zebra finch, just like injury to some parts of the human brain leads to selective language impairment. While specific melodic forms are learnt bynique fledglings, from the father bird, there is evidence that specific combinations of sound convey different meanings. This finding, in the case of the chestnut crowned babbler, a songbird of South East Australia, is a rare instance, outside human communication, of meaning conveyed by rearranging sounds.

In the case of the chestnut crowned babbler, it was found that out of at least 15 context specific calls, there were two groups, say A and B, apparently meaningless by themselves, but which were sounded as AB or as BAB, one specifically to maintain the flock in flight, and the other to motivate feeding, when with the young, in the nest. It was possible to replay these calls from a recording, and induce a bird to either look towards a window, for flight, or towards the nest - to show that the experimenter was 'speaking' with the bird.

Singing dog

It is in this context of working with the simplest systems in unravelling the mystery of vocal communication, that we have a case of melodic vocalisation and symphonic group cries of the New Guinea singing dog, or the New Guinea Highland dog. The debate is still on of whether this near extinct variety is same species as the domestic dog, and it is recognised that it has been isolated from the main evolutionary stream. The characteristic of the NGSD, not seen in dogs, wolves or dingoes, is the dramatic pitch modulation of its howl. The howl starts at a pitch of 600-800 cps, or about one octave higher than normal speech, and then swings to 300 cps, or a deep human voice, and high to 1700 cps, or two octaves higher than the start. The howl lasts as long as 5 seconds, with abrupt rise and fall of pitch and there are five to eight well defined overtones, which give the howl a musical quality.

There is also the chorus howl, or independent melodies sounded by more than one NGSD, where one starts and others quickly join. The participants of the chorus are said to be well synchronised, and can go on for ten minutes, usually coming to a stop simultaneously. A unique feature that the NGSD howl displays is the 'trill', a high pitched pulsed signal, "of a distinctly 'bird-like' character," and this is believed to be produced by the rapid vibration of a rudimentary uvula (the fleshy extension that hangs at the back of the soft palate).

While this instance of sophisticated vocalisation, outside the category of song birds, is an attractive opportunity to study the evolution of vocal ability, there have been no known specimens of NGSD in the wild for over 50 years and there are only 200-300 specimens in captivity. The NGSD is known to have been there in good numbers in the lowland of New Guinea, finds mention in travel records and was studied since over a century ago. But it was displaced by human colonisation and European and Asian derived dog lines, and has been considered extinct.

This belief is now reviewed, with the current study, which identifies a high altitude dog population, the Highland wild dog, in mountains of New Guinea, as the same line as the NGSD. These, the HWD, also show vocalisation like the NGSD and the team writing in PNAS has carried out DNA analysis, which shows close similarity of the HWD and the NGSD. The Vocalisation and genetic proximity "indicate the potential of the HWD to be a wild NGSD population," the paper says. The HWD may have been "the founding population of the NGSD" which "is not, in fact, extinct and the HWD should be resourced for conservation efforts to rebuild this unique dog family population," the paper says.

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