Will Robots Evolve into Crabs?

Nature keeps reinventing the crab. At least five times, unrelated crustacean lineages have independently converged on the same compact, flat, modular body plan. Biologists call it carcinisation. Engineers should be paying attention.

In this episode, we look at what the crab's repeated emergence tells us about the deep constraints that shape both biological and artificial systems. The crab body succeeds not because it is optimal in the abstract, but because its modularity creates a platform for downstream specialisation. The same logic applies to robotic morphology: compact, laterally stable, segment-based designs consistently outperform human-mimicking forms when the selection pressure is efficiency rather than aesthetics.

We extend the analogy into AI architecture, where the Transformer has undergone its own carcinisation, colonising vision, audio, robotics, and protein folding from its origins in language modelling. That convergence reflects shared hardware and training constraints, not architectural perfection. And just as crab-like forms have been lost at least seven times in nature through decarcinisation, the emergence of hybrid architectures signals that the Transformer monoculture may be a local optimum, not a final destination.

The core argument is that convergence signals constraint, modularity enables both convergence and escape, and the platform matters more than the form. Engineers chasing human mimicry or constant architectural reinvention may be solving the wrong problem. Nature solved it by building modular platforms and letting selection do the rest.