How do scientists infer the organization of a biological system from its behavior?

In systems biology, scientists infer the organization of a biological system by essentially performing "systems reverse engineering."1

Unlike systems engineering, where components are assembled to achieve a prescribed behavior, biologists must work backward from observable biological behaviors to determine the underlying structure. This process is challenging because biological systems are highly complex, involving a vast number of interactions with varying strengths that must be deduced after the fact.12

To infer this organization, scientists follow a multi-step approach:

• Component Identification: Researchers first identify the individual parts of the system, such as molecules, cells, or genes.21
• Property Analysis: They study the properties of these individual components to understand their basic functions.1
• Interaction Mapping: Scientists attempt to identify how interactions between these components create the system's observable behaviors. This is critical because many vital biological functions are "emergent properties"—collective behaviors that cannot be predicted by studying individual parts in isolation.1

Ultimately, this approach relies on computational and mathematical tools to analyze large data sets, allowing researchers to reconstruct the "blueprint" of the system from its genetic material and functional output.21