How should we assess the impact of genetic changes on ageing in model species?

One of the most active branches of genetic research is the quest for the genetic determinants of ageing. The ultimate goal of much of this effort is to understand ageing in humans. In addition to work on human genetics, many researchers look to model organisms in order to find genetic variation that can affect ageing. The fly Drosophila, the worm Caenorhabditis elegans, rodents, and yeast are among the most widely studied species. However, while great care is given to the genetic aspects of this form of research, the methods used to assess the impact of the genetic changes on the organism in question do not always provide as complete a picture as possible of ageing's multi-facetted nature. In this commentary, I propose a systematic and rigorous approach, and draw attention to research that has already demonstrated the value of such an approach.