literally hundreds of different bird species in a small area.To stand out
against both this cacophony of sound and other environmental noises,
and to be distinctive,may impose features such as tone and rhythm as
each species homes in on its own broadcasting bandwidth.Complex pat-
terns of songs and species differences in the rules that underlie them may
also have their origins in the need for distinctiveness.
But is this musicality? It is not difficult to find examples in animal song
of complex features that we would also attribute to music.In addition to
choruses and duets,some birds sing in near perfect scales (e.g.,musician
wren,Cyphorhinus aradus) and other features of our own music can also
be illustrated with examples from the animal kingdom (see Payne and
Mâche,this volume).But caution is required here.Considering only
songbirds (oscine passerines),there are close to 4,000 species in the
world,and all of them are thought to learn their songs.The variety in
the form and patterning of these songs is impressive,and it is likely that
many possible patterns remain unexplored given this huge array of
species.It would thus not be surprising if almost any characteristic found
in human music were discovered in one or a few of them.But such sim-
ilarities are likely to be coincidental,and certainly due to convergence
rather than because features of music arose in a common ancestor.
Nevertheless,although animals may not share music in the strict sense
with us,there is no doubt that some of them do have complex and
beautiful vocal displays.Understanding the reasons why they evolved
may help to shed light on why only we among the primates have gone
along a similar pathway.
One final point is worth making.It is suggested from time to time that
the songs of some birds that seem to us especially beautiful may be more
so than is strictly necessary for their biological function (Thorpe 1961;
Boswall 1983).Could this indicate some primitive aesthetic sense,and
that the bird is taking pleasure in song for its own sake? Candidates
would be songs of the song thrush in Europe,the superb lyrebird
(Menura novaehollandiae;Robinson and Curtis 1996) in Australia,and
the mockingbird (Mimus polyglottos; Wildenthal 1965) in North
America,all of which have large,varied,and beautiful repertoires.The
difficulty with such ideas is how to test them.Sexual selection is an open-
ended process that will lead to larger and larger song repertoires until
other constraints,such as storage space in the brain,set limits.Where it
is responsible,it is unlikely that song could be more elaborate than it
demanded.On the other hand,there is nothing incompatible between
this and either aesthetics or the enjoyment of song;indeed,sexual selec-
tion is likely to have been the basis for its evolution in humans.But this
is where the testability problem comes in.We personally feel enjoyment
in hearing or performing music,and we know that other humans do too,60 Peter J.B.SlaterMUS4 9/14/99 11:59 AM Page 60