In biology, structures and functions occur across a hierarchy of
size, extending from molecules to organisms.
The EBS database uses sixteen hierarchical levels to build a
qualitative framework onto which quantitative data can be attached.
Building such an framework is a continuous process. It starts
out as an "ideal" model that
acquiesces - over time - to the preferences being expressed in the literature.
- An organ hierarchy.
- A brain and spinal cord hierarchy.
- An literature-based hierarchy.