In the middle of each beach animal is a kind of spine, more specifically a crankshaft. The remarkable thing about this spine is that it can rotate. In the model, my hand turns the crank of the crankshaft. This rotation is converted by 11 small rods into a walking movement drawn by a small pencil at the end of the leg....Of course, I had no idea beforehand which ratio between the lengths I needed for the ideal walking movement. Which is why I developed a computer model to find this out for me.

But even for the computer the number of possible ratios between 11 rods was immense. Suppose every rod can have 10 different lengths, then there are 10,000,000,000,000 possible curves. If the computer were to go through all these possibilities systematically, it would be kept busy for 100,000 years. I didn't have this much time, which is why I opted for the evolutionary method...

Fifteen hundred legs with rods of random length were generated in the computer. It then assessed which of these approached the ideal walking curve. Out of the 1500, the computer selected the best 100. These were awarded the privilege of reproduction. Their rods were copied and combined into 1500 new legs. These 1500 new legs exhibited similarities with their parent legs and once again were assessed on their resemblance to the ideal curve. This process went through many generations during which the computer was on for weeks, months even, day and night.