The formal discussion of how animals appear to be designed to function in their environment started over 200 years ago when William Paley described how animals were adapted to their environment by an omnipotent designer. The modern environment that wild animals face is changing dramatically due to human activities. Over 50 years ago, Richard Levins described adaptive phenotypic plasticity as an evolutionary strategy that animals could use to adapt to such changing environments. My research focuses on understanding the evolutionary strategies and physiological mechanisms by which real animals in real places adapt to changing environments. In this seminar, I provide an overview of my past, current, and future research in wild animals. I show that wild red squirrels live in an environment where natural selection on offspring phenotype fluctuates across years but that maternal stress responses to cues of density-mediated selection cause adaptive developmental plasticity in offspring phenotype that allows them to cope with this variable environment. Secondly, I show how the hormonal mediation of broad patterns of variation in mammalian life histories may mediate but also constrain adaptive life history plasticity to a changing environment. Third, I show how individual variation and plasticity in pro-social (cooperative) behavior in free-living meerkats may be caused by individual differences in stress physiology such that some individuals are constrained to exhibit either a high or low level of pro-social behavior regardless of changes in their social environment. Overall, these three examples of my research highlight how studying questions at the interface of ecology, evolution, and physiology can lead to new insights into the role of phenotypic plasticity in facilitating and constraining contemporary adaptation to altered environments.