The adaptive immune system is able to learn from changing experiences to better fit an unforeseen future, thanks to a large and diverse collective of cells expressing unique antigen receptors and capable of rapid Darwinian evolution. However, naturally occurring immune responses exhibit limits in efficacy, speed and capacity to adapt to novel challenges. In this talk, I will discuss theoretical frameworks we developed to (1) explore functional impacts due to the nonequilibrium nature of antigen recognition, and (2) identify the conditions under which natural selection acting local in time can exploit environmental variation and functional constraints to find adaptable solutions favorable only in the long run.