In
lovers' songs, military
marches, weddings and
funerals — every
occasion where a degree
of emotion needs to be
evoked — music is an
indispensable
ingredient.
Yet
the ability to enjoy
music has long puzzled
biologists because it
does nothing evident to
help survival. Why,
therefore, should
evolution have built
into the human brain
this soul-stirring
source of pleasure?
Man's faculties for
enjoying and producing
music, Darwin wrote,
"must be ranked
among the most
mysterious with which he
is endowed."
Music
is still a mystery, a
tangle of culture and
built-in skills that
researchers are trying
to tease apart. No one
really knows why music
is found in all
cultures, why most known
systems of music are
based on the octave, why
some people have
absolute pitch and
whether the brain
handles music with
special neural circuits
or with ones developed
for other purposes.
Recent research,
however, has produced a
number of theories about
the brain and music.
It
could be that the brain
perceives music with the
same circuits it uses to
hear and analyze human
speech, and that it
thrills to its cadences
with centers designed to
mediate other kinds of
pleasure. Dr. Anne Blood
and Dr. Robert J.
Zatorre, of the Montreal
Neurological Institute,
recently took PET scans
of musicians' brains
while they listened to
self-selected pieces of
music that gave them
"chills" of
euphoria. The works
included Rachmaninoff's
Piano Concerto No. 3 and
Barber's Adagio for
Strings. The music, the
researchers reported,
activated similar neural
systems of reward and
emotion as those
stimulated by food, sex
and addictive drugs.
If
music depends on neural
circuits developed for
other reasons, then it
is just a happy
accident, regardless of
evolution, that people
enjoy it. This is the
position taken by Dr.
Steven Pinker, a
psychologist at Harvard
University. Music, he
writes in his 1997 book
"How the Mind
Works," is
"auditory
cheesecake" — it
just happens to tickle
several important parts
of the brain in a highly
pleasurable way, as
cheesecake tickles the
palate. These include
the language ability
(with which music
overlaps in several
ways); the auditory
cortex; the system that
responds to the
emotional signals in a
human voice crying or
cooing; and the motor
control system that
injects rhythm into the
muscles when walking or
dancing.
That
music can activate all
these powerful systems
at once is the reason it
packs such a mental
oomph, in Dr. Pinker's
analysis. But since each
of these systems evolved
for independent reasons,
music itself is no more
an evolutionary
adaptation than is the
ability to like dessert,
which arises from
intense stimulation of
the taste buds
responsive to sweet and
fatty substances.
But
other evolutionary
psychologists believe
the faculty of enjoying
music is no accident.
Darwin suggested that
human ancestors, before
acquiring the power of
speech, "endeavored
to charm each other with
musical notes and
rhythm." It is
because of music's
origin in courtship,
Darwin believed, that it
is "firmly
associated with some of
the strongest passions
an animal is capable of
feeling."
In his
theory of sexual
selection, Darwin
proposed that traits
found attractive in
courtship would enable
their owners to get more
genes into the next
generation. The upshot
would be the emergence
of adornments that had
no immediately obvious
survival value in
themselves, like the
peacock's tail or the
troubadour's ballads.
Darwin's
ideas about music have
been extended by Dr.
Geoffrey Miller, an
evolutionary
psychologist at the
University of New
Mexico. Dr. Miller notes
their potency in
pointing to the
opportunities open to
popular musicians for
transmitting their genes
to the next generation.
The rock guitarist Jimi
Hendrix, for instance,
had "sexual
liaisons with hundreds
of groupies, maintained
parallel long-term
relationships with at
least two women, and
fathered at least three
children in the United
States, Germany, and
Sweden. Under ancestral
conditions before birth
control, he would have
fathered many
more," Dr. Miller
writes.
Why on
earth would nubile young
women choose a rock star
as a possible father of
their children instead
of more literary and
reflective professionals
such as, say,
journalists? Dr. Miller
sees music as an
excellent indicator of
fitness in the Darwinian
struggle for survival.
Since music draws on so
many of the brain's
faculties, it vouches
for the health of the
organ as a whole. And
since music in ancient
cultures seems often to
have been linked with
dancing, a good fitness
indicator for the rest
of the body, anyone who
could sing and dance
well was advertising the
general excellence of
their mental and
physical genes to a
potential mate.
"Music
evolved and continues to
function as a courtship
display, mostly
broadcast by young males
to attract
females," Dr.
Miller writes in
"The Origins of
Music," a
collection of essays by
him and others.
But
other psychologists
argue that Dr. Miller's
courtship theory does
not do full justice to
another important
dimension of music, its
role in cementing social
relationships and
coordinating the
activities of large
groups of people. Dr.
Robin Dunbar, of
Liverpool University,
has shown that monkeys
spend a large amount of
time grooming other
members of their social
group, so much so that
they would scarcely have
time to look for food if
their 50-strong groups
were to grow any larger.
Dr.
Dunbar believes that the
much larger human
groups, of 150 members
or so, overcame the
grooming barrier by
developing a new kind of
social glue, namely
language. Group singing,
or chorusing, may have
been an intermediate
step in this process, he
suggests. He has
preliminary evidence
that singing in church
produces endorphins, a
class of brain hormone
thought to be important
in social bonding, he
said in an e-mail
message.
Others,
like Dr. Edward Hagen of
Humboldt University in
Berlin and Dr. Gregory
A. Bryant of the
University of California
at Santa Cruz, believe
the role of music in
human evolutionary
history was not to
create social cohesion
but to signal it to
rival groups. By putting
on a better
song-and-dance display,
a group could show it
had the coordination to
prevail in a scrap, and
could thus avoid a fight
altogether, they write
in an article
available on the Web.
Male
chimpanzees sometimes
chorus in a call known
as a pant-hoot, though
usually to attract
females to a new source
of fruit they have
found. For human
ancestors, musical
displays of this kind
"may have formed
the evolutionary basis
for the musical
abilities of modern
humans," Dr. Hagen
and Dr. Bryant write.
The Pentagon's vigorous
support of military
bands — $163 million
in 1997 — lends a
certain resonance to
this view.
The
courting and social
cohesion theories of
music's origins assume
that there are
structures in the human
brain that have evolved
specifically to handle
music. If no such
structures exist, then
Dr. Pinker's theory or
something like it is
correct.
A
leading clue that points
to music-specific
structures, yet is so
far not conclusive, is
that many features of
music are universal as
well as apparently
innate, meaning present
at birth. All societies
have music, all sing
lullaby-like songs to
their infants, and most
produce tonal music, or
music composed in
subsets of the 12-tone
chromatic scale, such as
the diatonic or
pentatonic scales. Some
of the earliest known
musical instruments,
crane bone flutes from
the Jiahu site in China,
occupied from 7000 to
5700 B.C., produce a
tonal scale.
Dr.
Sandra Trehub, of the
University of Toronto,
has developed methods of
testing the musical
preferences of infants
as young as 2 to 6
months. She finds they
prefer consonant sounds,
like perfect fifths or
perfect fourths, over
dissonant ones. A
reasonable conclusion is
that "the rudiments
of music listening are
gifts of nature rather
than products of
culture," she wrote
in the July issue of
Nature Neuroscience.
But
although certain basic
features of music, such
as the octave, intervals
with simple ratios like
the perfect fifth, and
tonality, seem to be
innate, they are
probably not genetic
adaptations for music,
"but rather appear
to be side effects of
general properties of
the auditory
system," conclude
two Cambridge
scientists, Josh
McDermott of the
Massachusetts Institute
of Technology and Dr.
Marc Hauser of Harvard,
in an unpublished
article.
The
human auditory system is
probably tuned to
perceive the most
important sounds in a
person's surroundings,
which are those of the
human voice. Three
neuroscientists at Duke
University, Dr. David A.
Schwartz, Dr. Catherine
Q. Howe and Dr. Dale
Purves, say that on the
basis of this cue they
may have solved the
longstanding mysteries
of the structure of the
chromatic scale and the
reason why some
harmonies are more
pleasing than others.
Though
every human voice, and
maybe each utterance, is
different, a certain
commonality emerges when
many different voices
are analyzed. The human
vocal tract shapes the
vibrations of the vocal
cords into a set of
harmonics that are more
intense at some
frequencies than others
relative to the
fundamental note. The
principal peaks of
intensity occur at the
fifth and the octave,
with lesser peaks at
other intervals that
correspond to most of
the 12 tones of the
chromatic scale, the
Duke researchers say in
an article published
last month in the
Journal of Neuroscience.
Almost identical spectra
were produced by
speakers of English,
Mandarin, Persian and
Tamil.
The
Duke researchers believe
the auditory system
judges sounds to be
pleasant the closer they
approximate to this
generalized power
spectrum of the human
voice. "A musical
tone combination whose
power is concentrated at
the same places as a
human speech sound will
sound more familiar and
more natural," Dr.
Schwartz said.
Some
people are unable to
appreciate music,
raising the question of
whether some
music-specific faculty
has been damaged. People
who are tone deaf also
fail to hear pitch
changes in the human
voice, so this deficit
does not seem specific
to music. Some patients
have music agnosia, an
inability to recognize
familiar melodies, even
ones to which they know
the lyrics. But the
brain has to store
memories about music
somewhere, and the music
agnosia patients could
have incurred memory
damage that just
happened to hit the
music archive, Mr.
McDermott, of M.I.T.,
said.
"Any
innate biases on music
must derive from
something in the brain,
but at present there is
little evidence for
neural circuitry
dedicated to
music," Mr.
McDermott and Dr. Hauser
conclude.
Dr.
Zatorre, of the Montreal
institute, takes a
similar view. The brain
has evolved faculties
for perceiving sounds,
organizing events in
time and maintaining
memory stores, he said.
"Once you've got
all that hardware in
place, it can be used
for a lot of different
purposes. But I don't
think it follows that
music was selected
for."
Whether
music is cheesecake,
courtship or cohesion,
its mystery remains
unbreached.