The cover features an interpretation of the classic textbook illustration the Ascent of Man. Over the years, there have been several album covers based on the chart that shows an ape evolving into a man walking upright. The one that comes first to my mind is the 1985 Supertramp album Brother Where You Bound (right).
The Take That album features images that represent the members of the group, Gary Barlow, Howard Donald, Jason Orange, Mark Owen and Robbie Williams. (Do not expect me to identify the order in which they appear.) Rather than evolving from an ape, the "progress" shown on this cover seems to be a spiritual evolution. It puts a slightly new spin on a concept that we've seen before.