Music, Evolutionary Cheesecake And The Designer Brain

Physicist Emerson Pugh once quipped, “if the human brain were so simple that we could understand it, we would be so simple that we couldn’t” [1]. In his book This Is Your Brain On Music neuroscientist Daniel Levitin notes how the number of ways that brain neurons can connect is so vast that we will never fully comprehend all the thought processes that we are capable of.

In recent years, mapping techniques have revealed a lot about the functional regions of the brain. Wernicke’s area is responsible for language processing, the motor cortex for physical movement and frontal lobes for generating personalities. Both encephalography and MRI have given us key spatial-temporal data about brain function in these regions. But we also find that activities such as listening to music contravene such a simplistic compartmentalization.

In fact the perception of pitch, tempo, the emotions invoked by a piece of music and the lyrics of a song all use different parts of the brain albeit simultaneously. Levitin repeatedly emphasizes the multi-faceted aspects of the music ‘experience’ noting how a, “precision choreography of neurochemical release and uptake” leads to our appreciation of music [p.188]. The brain is thus a massively parallel device, capable of carrying out several different tasks at once.

While it is through a lifetime of exposure that our brains become used to the note scales and music styles of our culture, it is during childhood that we are most receptive to learning music rules and note sequences. The finding that children’s tastes in music are heavily influenced by the music heard during prenatal development, has forced a shift in the way we think about childhood memory.

We now know for example that the cerebellum has the capacity to recall with precision accuracy the rhythm of a music piece long after it has been heard while the brain stem and dorsal cochlear nucleus are able to distinguish between consonant (harmonious) and dissonant sounds. In fact our brains are able to group sounds without any conscious effort from ourselves.

We rarely have difficulty deconvoluting the sounds of instruments- a trumpet will always sound like a trumpet and a clarinet always a clarinet. Every instrument has its own characteristic ‘fingerprint’ of tone frequencies many of which can now be copied by electrical synthesizers. Indeed frequency modulation synthesis has allowed musicians to simulate instruments and incorporate their own unique sounds into their music.

Levitin’s work at Stanford University has brought to light our capacity to faithfully remember music pieces in their original pitch and tempo. In essence the brain can re-deploy (’re-member’) the same neurons that were used in the original perception of a music piece. The sound separation capabilities of the brain, which allow it to differentiate between concurrent sounds (say two different instruments), are nothing short of remarkable.

We are only just beginning to understand how it is that the brain registers the sound signals that cause our ear drums to wiggle at certain frequencies. Feature extraction is the process through which neural networks then ‘decompose’ the sound signal into information about pitch, timbre and loudness amongst other things. Through repeated exposure, our brains generate ’schemas’ of what sounds should go together, what letters will appear in a word and what different types of music will sound like.

Levitin does a fantastic job in explaining the universal patterns and regularities of musical construction revealing the common music elements that unite apparently disparate pieces of music such as those of Mozart and The Eagles, Prokoviev and Steve Wonder. The non-arbitrary frequency distances between notes are what identify any given piece of music.

Levitin makes his book that much more exciting by recounting many of his own personal stories both as a musician and a neuroscientist. His work as a record producer with some of the biggest names in the business and some of the best-known artists of contemporary rock provides a unique flavor to his scientific discussion.

Nevertheless his conversations on evolutionary biology and its relevance to brain evolution with the greats of molecular genetics, notably Francis Crick and James Watson, are somewhat of a disappointment. Indeed in the last chapter Levitin develops the idea that music has served as a ‘vehicle’ for social bonding and cohesion citing the tendency of people to identify with others with similar music tastes as supportive evidence. He is quick to dismiss psychologist Steve Pinker’s assertion that music was nothing more than ‘evolutionary cheesecake’ that in humans rode on the back of the more critical adaptation of language.

Rather, Levitin sees music and musical appreciation as an adaptation in itself that may have allowed sexual partners to charm each other through their courtship displays (an extension of Darwin’s theory of sexual selection). He cites the highly social and musical tendencies of Williams Syndrome patients and the musical and social difficulties of autistic children as clear evidence of an evolutionary connection between music and social integration. But what of the complexity that Pugh so eloquently drew our attention to so many years ago?

Naturalist Jane Goodall expressed her views on evolution when she wrote of, “a series of vanished brains, each more complex than the one that came before it” [2]. And yet without the crucial evidence of the ‘how’- the mechanistic meat of evolutionary theory- the role of natural selection, particularly as relates to music appreciation, remains but a skeleton of speculation.

Literature Cited
1. Inside The Mind Of God- Images And Words Of Inner Space, Introduction By Sharon Begley, Edited By Michael Reagan, Templeton Foundation Press, New York, p.61
2. Jane Goodall (1999) Reason for Hope: A Spiritual Journey Warner Books Inc, New York, NY, p.126