The history of life on earth is marked by major innovations, traits that often change what is possible. However, these transformative events often come with trade-offs and constraints, shaping the available strategies and increasing the predictability of short-term ecological and evolutionary responses.

To illustrate this argument, in this talk, I will briefly discuss how the evolution of multicellularity both opened important alternatives and, at the same time, constrained immediate ecological responses. Finally, I will argue that innovations and key transitions in metabolic architecture create important constraints in the short term; a better understanding of these metabolic rules can better allow us to understand and predict present microbial communities.