Miller,^14 by contrast, considers music to exemplify many of the classic criteria for a
complex human adaptation: (1) No culture in any period of recorded history has been
without music (i.e. universality). (2) The development of musical abilities is orderly.^15 (3) The
ability is widespread in the sense that almost every normal adult can appreciate music and
carry a tune (i.e. basic perceptual and performing skills). (4) Adults can recognize thousands
of melodies, implying specialized memory. (5) Special-purpose cortical mechanisms are
involved.^16 (6) There are analogues in the signals of other species such as songbirds,^17
gibbons,^18 and whales,^19 raising the possibility of convergent evolution. (7) Finally,
music can evoke strong emotions,20–23which implies receptive as well as productive
adaptations.
If music is a complex biological adaptation rather than a by-product of other evolu-
tionary processes, it must have conferred survival or reproductive benefits through the
cumulative effect, over generations, of natural selection or sexual selection.14,24,25The costs
of music production—energy expenditure—must be balanced by benefits. Because no sur-
vival benefits are obvious, Miller^14 argues for the evolution of music on the basis of its
reproductive benefits. In other words, he makes a case for music as sexual courtship. He
argues that although music is typically performed ingroups, it is not forgroups (but see
Ref. 26; Huron, Chapter 4, this volume). In the context of the tribal group, dancing (i.e. vig-
orous movement to music) could have provided a means for young women to assess the
strength, endurance, and motor coordination of potential mates. The relative stability of
ancestral social groups would have allowed women to scrutinize prospective partners over
an extended period. Miller^14 acknowledges, however, that aesthetic preferences would have
been equally effective as a basis for sexual selection.
Sexual (or natural) selection of this nature would lead to the replication of genes related
to receptive and productive musical potential. In fact, genetic correlates of musical pitch
processing have been identified.^27 Musical processing predispositions or biases might
be evident in infancy, well before they have obvious utility. As Cross^28 argues, it may be
possible to observe the impact of evolutionary processes in infancy before any musical
culture has left its indelible impression.
Uncovering musical predispositions
Accessing the music processing skills of preverbal listeners is no easy matter. Nevertheless,
researchers have made considerable headway by means of conditioning procedures,^29
habituation procedures,30,31and preference procedures.32,33The most common conditioning
procedure involves the presentation of a repeating melody or tone sequence from a later-
ally displaced loudspeaker while infants watch a puppet show. Periodically, the repeating
pattern changes in some way, which prompts infants to turn towards the loudspeaker.
Correct responses (i.e. turns) immediately following the change are rewarded by the
presentation of a colourful mechanical toy (e.g. dancing bear, acrobatic monkey). Failure
to turn at such times and turns at other times have no consequences. Such response-
contingent rewards motivate attentive listening for 10–15 min, or 20–30 test trials. Aside
from the bears, monkeys, puppets, and other paraphernalia that facilitate communication
with nonverbal participants, the task is similar to adult same–different tasks. Infants turn
4