The soul-era R&B of the 60s and 70s was marked by raw emotion and vulnerability, but by 2000, the dominant R&B sound was invulnerable. Singers like Beyonce and Mary J. Blige pull off precisely choreographed displays of power, as thrilling as watching a tightrope walker show off mid-act. Akon and Kelis draw on hip-hop for songs that are cocksure and pointedly unsentimental. Only the cyborgs flash any emotion, as T-Pain sweet talks through his robo-filter and Janelle Monae heightens her act by letting you hear her sweat, just a little bit.