I am an ecologist by training, but as a student I quickly realized that physiology is needed to get more profound understanding of how ecological processes affect individuals and even of why individuals behave as they do. Early on I was interested in animal behaviour and studied the effects of early-life immune challenge on personality development, but later I got fascinated by aging. My main interests today lie broadly in aging and stress biology that I like to put in an ecological framework. In my PhD work I used telomeres, the protective caps of chromosomes that are linked to aging and survival, as biomarkers for studying how different lifestyles and environments affect the survival trajectories of individuals or populations, using the pied flycatcher as a model species. Currently, in my post-doctoral project I am combining my old interest in behaviour with the present interest in aging by investigating the link between reproductive behaviour and telomeres. I am also developing a growing interest in mitochondrial traits, a promising venue in the aging research, and how physiological markers could be used in conservation biology.