The complementation of protocells can be regarded analogously to the complementation by “music minus one” electronic media that provides soloists with a complete orchestral accompaniment with the solo part missing. A programmable complementation system can consecutively reduce the level of support, increasing the degree of autonomous orchestration of the chemical system. In principle, a smooth succession of environmental challenges can be provided, easing the combinatorial search for viable artificial cells down to manageable steps, starting from a fully supported system in which all aspects of the protocell are under microfluidic control. Of course, the difficulty of the individual steps is dependent not only on the innate evolutionary potential of the chemical system at each stage, but also on the aptness of engineered changes to its composition. In addition, and perhaps less obviously, a combinatorial succession or array of different environments can be used to enhance the effective evolvability of the chemical system, especially at early stages.
For some first steps towards evolutionary complementation microsystems for artificial cells, see the experimental pages of our site.