From the abstract: "This chapter suggests that the original function of music is most likely associated with social bonding once group sizes became too large to be adequately bonded using grooming alone. It also contends that music served a natural bridge to language as language became inevitable as a mechanism for group bonding and cohesion."
http://www.oxfordscholarship.com/view/10.1093/acprof:osobl/9...
From the abstract: "This chapter suggests that the original function of music is most likely associated with social bonding once group sizes became too large to be adequately bonded using grooming alone. It also contends that music served a natural bridge to language as language became inevitable as a mechanism for group bonding and cohesion."