If the Darwinist theory is the proper metatheoretical model of all social sciences including economic science, as the authors of this book claim, what does it tell us economists about the maximization hypothesis? In regard with the consumption of matter and energy of the living entities the authors of Darwin’s Conjecture asserts that they “have limited capacities to absorb” (p.33). However, there is a magnitude which is maximized by replicators - the number of offspring. But enough disappointing, human reality seems to be depicted by an upside down situation: it is rather the number of offspring which humans strive to limit and it is each individual’s consumption of matter and energy that is maximized. The authors do not seem aware of this serious contradiction and are not at all concerned to account for by a more comprehensive principle that reconcile these two principles of limitation and maximization, which apply differently to human and non-human living worlds.
I think this doesn't really hit the mark. Human offspring is what a naive human-centric, DNA-centric view of evolution might point to as evolution's maximand. It isn't that far from the mark - as today's 7 billion humans attests to. However, human DNA is only one of the things copied in evolution. There are also plants, bacteria and memes. Memes are what explains the demographic transition which Paul alludes to. Gene-meme coevolution is the only credible theory that accounts for the reduced levels of offspring creation associated with being a rich westerner. There's been quite a bit of effort put into understanding how it works.
There is no "principle of limitation" that only applies to the human world. Maximization explains things pretty neatly. The maximand isn't human offspring, though - memes count too. We are already witnessing the effects of high meme concentrations on human fertility - for example, in Japan. In the future, the number of humans may well dwindle - as existing humans get sucked into cyberspace and fail to procreate. This would not be a failure of Darwinian evolution - it will just illustrate one type of information being copied at the expense of another. Ultimately, entropy is the maximand - as has been argued by many.
Entropy maximization is consistent with Paul's claim that we should look to physics - and not biology - for the answer here. However, entropy maximization isn't really a replacement for evolutionary theory - it is more of a useful adjunct.