I would recommend the 2nd law entropy maximization approach, which attempts to account for instances of increased genetic success by their increase in the rate of entropy generation.

Looking through the Citizendium Life article footnotes, I found this article (footnote 28) that I'm reading now, which does so. It also explores the thermodynamic role that perception plays (in mammals and other organisms), which looks to be a promising piece of the puzzle of consciousness. The article sounds flaky at first, but it's clearly looking for (what we would call) a reductionist explanation of the purposefulness of complex organisms.