When you get large, directed systems—(e.g., we are composed of 40 trillion cells, each containing tens of millions of proteins)—I think you basically need some level of modularity if there’s any hope of steering the whole thing.
This seems basically right to me. That said, while it is predictable that the systems in question will be modular, what exact form that modularity takes is both environment-dependent and also path-dependent. Even in cases where the environmental pressures form a very strong attractor for a particular shape of solution, the “module divisions” can differ between species. For example, the pectoral fins of fish and the pectoral flippers of dolphins both fulfill similar roles. However, fish fins are basically a collection of straight, parallel fin rays made of bone or cartilage and connected to a base inside the body of the fish, and the muscles to control the movement of the fin are located within the body of the fish. By contrast, a dolphin’s flipper is derived from the foreleg of its tetrapod ancestor, and contains “fingers” which can be moved by muscles within the flipper.
So I think approaches that look like “find a structure that does a particular thing, and try to shape that structure in the way you want” are somewhat (though not necessarily entirely) doomed, because the pressures that determine which particular structure does a thing are not nearly so strong as the pressures that determine that some structure does the thing.
This seems basically right to me. That said, while it is predictable that the systems in question will be modular, what exact form that modularity takes is both environment-dependent and also path-dependent. Even in cases where the environmental pressures form a very strong attractor for a particular shape of solution, the “module divisions” can differ between species. For example, the pectoral fins of fish and the pectoral flippers of dolphins both fulfill similar roles. However, fish fins are basically a collection of straight, parallel fin rays made of bone or cartilage and connected to a base inside the body of the fish, and the muscles to control the movement of the fin are located within the body of the fish. By contrast, a dolphin’s flipper is derived from the foreleg of its tetrapod ancestor, and contains “fingers” which can be moved by muscles within the flipper.
So I think approaches that look like “find a structure that does a particular thing, and try to shape that structure in the way you want” are somewhat (though not necessarily entirely) doomed, because the pressures that determine which particular structure does a thing are not nearly so strong as the pressures that determine that some structure does the thing.