humans the world over engage in a host of activities that carry no
clear adaptive value. To illustrate this, consider the auditory cortex of
humans, which must perform several complicated tasks. One of these
is to sort out the sounds of language from other noises. Information
about noises is sent to associative cortical areas that categorize the
sounds and identify the nature of their source. Information about the
source's location is handled by other specialized circuitry and sent to
specific systems. The auditory system must also isolate the sounds of
language. All normal humans have the ability to segment a stream of
sound emerging from someone else's mouth in terms of isolated
[132] sounds, then send this purified representation to cortical areas spe-
cialized in word-identification. To turn a stream into segments, the
system must pay attention to the specific frequencies that define each
vowel and the complex noises of consonants, as well as their duration
and their effects on each other. To do this, the auditory cortex com-
prises different subsystems, some of which specialize in pure tones
and others in more complex stimuli. All this is clearly part of a com-
plex, evolved architecture specialized in fine-grained sound analysis, a
task of obvious adaptive value for a species that depends on speech for
virtually all communication. But it also has the interesting conse-
quence that humans are predisposed to detect, produce, remember
and enjoy music. This is a human universal. There is no human soci-
ety without some musical tradition. Although the traditions are very
different, some principles can be found everywhere. For instance,
musical sounds are always closer to pure sound than to noise. The
equivalence between octaves and the privileged role of particular
intervals like fifths and fourths are consequences of the organization
of the cortex. To exaggerate a little, what you get from musical sounds
are super-vowels (the pure frequencies as opposed to the mixed ones
that define ordinary vowels) and pure consonants (produced by rhyth-
mic instruments and the attack of most instruments). These proper-
ties make music an intensified form of sound-experience from which
the cortex receives purified and therefore intense doses of what usu-
ally activates it. So music is not really a direct product of our disposi-
tions but a cultural product that is particularly successful because it
activates some of our capacities in a particularly intense way.^36
This phenomenon is not unique to music. Humans everywhere also
fill their environments with artifacts that overstimulate their visual cor-
tex, for instance by providing pure saturated color instead of the dull
browns and greens of their familiar environments. This has been so for
RELIGION EXPLAINED