The field of systems biology has emerged as the bridge between reductionist molecular and cellular biology approaches and the systems-level understanding required to use this knowledge to advance the human condition. Drawing upon the revolutionary advances from reductionist approaches in molecular and cellular biology, systems approaches focus on the relationships between the gene, protein, and metabolite responses that compose the individual and population responses at the whole organism level. The primary avenues in this search are (i) defining the causal connections between the plethora of transcriptional, protein, and metabolite players; (ii) linking these microscale networks to system response; and (iii) capturing the dynamics of the system in response to changes at lower scales.