Rather than the term 'logical' I would think of 'reasoned', human made systems in general tend to be designed through reasoned, deterministic processes. This means that from any point in the system, no matter how large or complex, you should be able to logically determine what the adjacent points in the system are, from an endpoint you can backtrack your way to the origin.
Biological systems are 'designed' through stochastic processes, which means that from any point in the system we can only make a probabilistic guess as to what points are adjacent to it. This works well for solving small problems, like predicting the next word in a sentence (language of couse being a natural, not human designed process), but this requires us to have a large corpus of example data, and doesn't scale well to trying to extract an entire book from one word.
So trying to fully understand large biological/natural systems is much harder than trying to decode an equally complex human created system.
Biological systems are 'designed' through stochastic processes, which means that from any point in the system we can only make a probabilistic guess as to what points are adjacent to it. This works well for solving small problems, like predicting the next word in a sentence (language of couse being a natural, not human designed process), but this requires us to have a large corpus of example data, and doesn't scale well to trying to extract an entire book from one word.
So trying to fully understand large biological/natural systems is much harder than trying to decode an equally complex human created system.