Before revision:  The model predicts, under fairly general assumptions, the emergence of an hourglass pattern in terms of the number of state-transitioning genes during development. Additionally, the evolutionary age of those genes also follows an hourglass pattern, with the oldest genes concentrated at the hourglass waist.
After revision:  The model predicts, under fairly general assumptions, the emergence of an hourglass pattern in the structure of a temporal representation of the underlying gene regulatory network. The evolutionary age of those genes also follows an hourglass pattern, with the oldest genes concentrated at the hourglass waist.