My first reaction was: wat? Isn't that only from the perspective of a relatively complex organism? Life constantly explores in all the directions it can, so it'

My first reaction was: wat? Isn't that only from the perspective of a relatively complex organism? Life constantly explores in all the directions it can, so it's no wonder that one frontier of that exploration is towards increasing complexity. And there are natural limits to decreasing complexity. (Though those limits are beyond what we would call "life". You don't need to be capable of reproduction if you can borrow a host's capability. We're all just host mechanisms for the parasitic reproduction of Pollan's corn, Adams's digital watches, and bad analogies.) Maybe that's what the abstract referred to as "the Theory of the Adjacent Possible"? I've only read the abstract. But your argument of ecosystem complexity is totally valid. Though I guess if an ecosystem decreases in complexity, then it has to end up in a different type of simplicity than it was the last time it was there, because otherwise you already know that it evolves out of that spot (assuming some amount of determinism). Temporarily, though, this can and does happen. Invasive species often obliterate a lot of complexity, presumably until either their weaknesses are discovered through the very changing conditions that allowed the natives to flourish in the first place, or until they evolve complexity of their own. There's another way to derive increasing complexity from a small number of laws, though. There are multiple resources and multiple ways to access them. Optimizing for any one of those results in overspecializing and becoming less fit for accessing most of the others. There's no one best answer that works for everything. You always have a delicate balance between overgeneralizing and overspecializing, and the area between those provides a lot of different ecological niches, and even more if you look at the battle stretched out over time. (The configurations are unstable; you could have a thousand species optimized for particular resources that get clobbered by a generalist that poisons the specialists, then the energy required by the poisoners makes them lose out to generalist nonpoisoners, which enables specialization again, not to mention evolved immunity... the wheel goes round and round, picking up crud as it rolls.)