The history of biology is peppered with groundbreaking discoveries: Charles Darwin's publication of `The Origin of Species', the determination of the structure of DNA, and, in 2000, the sequence of the human genome was finally added to this illustrious roll call. Two international teams of scientists announced that they had decoded the blueprint of life, but what exactly did the human genome tell us about life itself? According to Andrew Cossins from the University of Liverpool, `the basic information that the genome gives us is a parts list', but this `parts list' came without an `instruction manual'. However, scientists still know little about how the 20–25 000 protein coding genes on the human genome, which make up the genotype, interact with the environment to generate the observable phenotype that scientists study.

While unravelling this instruction manual seems like a daunting task,Cossins explains that it has the potential to revolutionise the study of animal function. With this in mind, Cossins and George Somero from the Hopkins Marine Station at Stanford University have compiled and edited the reviews published in this issue of The Journal of Experimental Biology, with the aim of demonstrating how genomic approaches could be added to the physiologists' toolkit. Written by leading scientists working at the forefront of the genomics revolution, each article discusses concepts, ideas and techniques for understanding how an organism's genotype contributes to the functioning of the whole organism under the complex suite of environmental factors it encounters in its habitat.