People with Alzheimer's are able to participate in group singing and some longer-term benefits are perceived by their carers. In a group activity such as Singing for the Brain it is difficult to be certain how the overall effect arises from the interaction of individuals. The data assembled is difficult to submit to clinical testing, relying as it does on the judgement of participants regarding reported recall of the content of sessions on the part of people with Alzheimer's. Further research questions are raised by the success of this project.

The impression has formed in the literature dealing with Darwin's life and achievement that he was himself unmusical, and that his theories have offered little help in understanding or valuing the role of music in human society. This article draws on biographical information relating to Darwin's family and household to illustrate that he was in fact surrounded by music throughout his life. While Darwin's deterioration in health may have reduced his ability to appreciate music in later life, he was clearly much involved in music as a young man. He also employed music in several of his experiments in animal behaviour, involving members of his family as co-researchers. A close reading of The Descent of Man that forms the central focus of this article illustrates the extent to which, throughout the book, Darwin made reference to musical behaviours in defining and illustrating his themes of natural and sexual selection. Ensuing correspondence with his sons consulted in the Darwin Archive at Cambridge University Library conveys the difficulty he had in dealing fully with music as a human capacity in its own right. However, far from his having little to say about music, Darwin's theories of natural and sexual selection robustly define the research agenda for exploring the purpose of music and its relation to language: a project that recent developments in neurology, anthropology and linguistics have begun to reveal in a new light.

Humans exhibit what appears to be a unique vocal property: octave equivalence whereby adult male voices are, on average, an octave lower in pitch than those of adult females and children. The evolutionary significance of this seems largely to have escaped notice. While sexual selection might explain why male voices are generally lower, it cannot explain why they should be so much lower than what would be expected for body size, nor why the average difference should be exactly one octave. Nor does a generalised dimorphism convey why precisely tuned octaves feature so commonly in human vocal interaction. The octave features strongly in the organisation of music. A consequence of this characteristic of human pitch perception and production is the capacity to share and respond to vocal pitches (and their instrumental equivalents) as if they are ‘the same’ irrespective of the difference in range, a phenomenon known as octave equivalence. We investigate the nature of octave equivalence from an adaptive perspective and propose a hypothesis for its evolution based on the importance of chorusing for social bonding and pitch-matching in inter-generational exchange.

A growing consensus drawing on research in a wide variety of disciplines has, over the last fifteen years or so, argued the need to revisit Darwin's conjecture of 1871 that language may be descended from an existing, musical medium of communication that developed from animal calls. This paper seeks to examine, in an extension of Hockett's analysis of the design features required for linguistic communication, the nature of the acoustic information produced and perceived in human vocalisation, and to consider the anatomical and neural mechanisms on which these depend. An attempt is made to sketch an evolutionary chronology for key prerequisites of human orality. Cross-species comparisons are employed to illuminate the role of four acoustic variables (pitch, duration, amplitude and timbre), viewing the potential for human vocal productivity from the perspective of animal communication. Although humans are the only species to combine entrainment to pulse with attunement to precisely-tracked pitches, we also depend both for musical interaction and the production and perception of vowel sounds on precise and conscious control of the property of timbre. Drawing on, amongst others, Scherer's analyses of emotionally triggered sounds in a variety of species, and Fernald's presentation of the similarities of infant cries and adult production of infant-directed speech in a variety of cultures and languages, a case is made for the instinctive components of human communication being more music-like than language-like. In conclusion, historical and comparative data are employed to outline the adaptive and exaptive sequence by which human vocal communication evolved. The roles of selective pressures that conform to different adaptive models are compared⎯natural selection, sexual selection, group selection⎯leading to the proposal that all of these must have played their part at different stages in the process in a 'mosaic' model consistent with the development of other human traits.

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