As a reaction to the more laid back style of cool jazz and west coast jazz, in the mid-1950s some musicians returned etc the ethos of bebop, but combined it with the gospel influences and the emerging styles of rhythm and blues. They created a 'funkier' type of music that was more blues-based, with simpler melodies. Some people called it 'funky hard bop', which pretty much sums it up. Some writers have suggested that hard bop was an attempt to recapture jazz as an overtly African-American art form, while drummer Shelley Manne thought it was more to do with environment, with west coast cool reflecting the Californian climate and hard bop being a product of the hyperactive environment of New York.