Week 14: Evolution

Language and music are two very specific human traits/qualities. The ability to speak fluently and to attach meaning to music clearly separates humans from animals. Although animals use music/song-like sounds for mating and warnings, there is no evidence that they are able to attach any meaning to their sounds. Language and music can be referred to as being “evolved” in human lineage. But the debate between “evolution” and “frill”, still pursues.

Language and Natural selection is viewed as a social construct. Some believe that language evolved to provide humans with a medium for expression and communication i.e. individual cognition=cultural cognition. Several arguments support the view of language and natural selection:
1) Babbling - occurs in all babies (across cultures, deaf/hearing) around 7 months. Evidence of selection, not imitation.
2) Human vocal tract – compared to animals, larynx sits lower, doesn’t connect with nasal passage
3) Vocal learning – producing vocal signals based on auditory experience (unique to humans). Neural substrates of vocal learning are not well understood
4) Speech perception of sound structures – 6 month old infants learn vowel sounds but soon loose sensitivity to phonetic contrasts in other languages.
5) Critical periods – for language, it is suggested that this ends at puberty
6) Commonalities in spoken and signed language – sign/spoken use same left brain i.e. can make use of different modalities
7) Robustness of language acquisition- even with minimal input.
8) Learning predispositions – e.g. Nicaraguan system of sign language
9) Gene mutation – when FOXP2 gene is damaged, speech and language issues pursue.

Music and Natural selection
Regardless of its lack of survival value, it has persisted. Evidence of it’s natural selection include:
1) Adaptionist hypothesis – sexual selection (Miller, peak in musical interests at adolescence), mental and social development (Cross), social cohesion
2) Music and language contain similar elements of natural selection (critical periods, robustness, babbling)
3) Infant studies – “music as adaption” view suggests we are born musical. Experiments with perceptual predispositions (chicks and quails) and innate learning preferences see findings on infant research p. 379
4) Genes and music – absolute pitch, tone-deafness, genes (FOXP2)
5) Similarities between man and animal – AP, ability to discriminate between consonance and dissonance, tonality (octave equivalence).

Beat-based rhythm processing
- Speech rhythm and beat-based rhythm share same metrical construction of stresses although speech rhythm does not have a regular pulse.
- Synchronization is based on temporal anticipation (tap slightly ahead of beat)
1) Development studies are used to study innateness of beat-based rhythm and perceptual studies aid in determining periodic temporal expectancies form musical stimuli
2) Synchronized movement to a beat is human specific (animals can sync with each other). Basal ganglia responsible for beat perception Having the neural circuitry for complex vocal learning is a necessary prerequisite for the ability to synchronize with an auditory beat.

A view poignant points:
Music is universal because it is universally valued
Human traits are researched using null hypothesis.
Musical aptitude appears to follow a path of natural selection e.g. individuals with selective amusia, and genetically passed on tone deafness.
Natural selection in music and language is still debated