One of the most interesting investigations I have
recently come across is the decipherment of the hoo sounds produced by gibbons.
Gibbons are apes that live mainly in Southeast Asia. They are known for their
loud songs but they can produce also a kind of whispers known as “hoo calls”. Hoo
calls are difficult to distinguish by the human ear but recently a group of
researchers succeeded to record and analyse them by using modern computer
technology. The gibbons investigated were groups of lar gibbons in North-eastern
Thailand. They were followed during four months from the morning till the
evening. The sounds were recorded and the researchers noted the event that
elicited the response. Back home they managed to distinguish and analyse the “gibbonish”and
to relate the hoo-calls to the events that had elicited them with advanced computer
techniques, so that it was no longer gibberish for them.
The results are surprising and important. The
researchers could identify more than 450 hoo sounds and connect them with the
situations in which they were uttered. In this way they found that – and now I
quote from an article in the Science
Daily (see below) – “distinct hoo calls are made in response to specific
events, such as foraging and encountering neighbours, and that subtle
differences even distinguish between different predators when used as a
warning.” For instance, the gibbons are able to warn their companions for
tigers and leopards with a sound meaning something like “big cat”. They use different
other hoos for specified other predators (like snakes and eagles). They can also
mobilize other gibbons for going to look for food together. They have hoo calls
for meeting together, greetings, delimiting their territory etc.
As the researchers say, this study is very relevant in
the debate on the evolution of human speech, seen as an ability to produce
context-specific sounds for communicating meanings to other recipients. But if gibbons
have a kind of speech – and so it seems – I have a question: Is a gibbon a sort
of human being? If we follow Aristotle the answer will be “yes”, for in the Politica (Book One, Part II) he says
that man is the only animal whom nature has endowed with the gift of speech. In order to show that a gibbon is a man, let me formulate
a syllogism in the sense of Aristotle:
All gibbons are endowed with the gift of speech
Only man is endowed with the gift of speech
So gibbons are men
I think that there are good reasons not to accept the
conclusion, but then one of the premises must be false. As it looks now most
likely the second premise (minor) is. But does it make a difference whether or
not a gibbon is a sort of man? Look around: Sometimes we get the impression
that men behave “like animals”. Actually this expression is an insult to the
animals. What a mesh we, men, have made of this world. One of the best developed
techniques of human behaviour is waging war. We are more and more destroying
our own environment in that way that it can lead to the end of human
civilization in the long run. And before this will happen probably we’ll have
destroyed already the life world of the gibbons, because we’ll have
irretrievably damaged their forest habitat. Then not only another precious
species will have become extinct but also a unique language will have gone, and
with it we’ll have lost a part of our own cultural heritage.