This painting appears to have qualities usually found in 20th Century Surrealist works, but in fact it is a piece from the Dutch Renaissance circa 1504. It also has a somewhat unorthodox presentation, being that it is contained within a shuttered "box" that is also part of the artwork. Although it is arguably rich in many symbols, the piece originally was meant to illustrate the Garden of Eden juxtaposed alongside Hell. Knowing this (and examining the details) the implications of choosing this work to serve as the cover image for Oryx and Crake are very clear.
Here is a larger version of the panel: