  A central problem of neuroscience involves uncovering the principles
governing the organization of nervous systems which ensure robustness in brain
development. The nematode Caenorhabditis elegans provides us with a model
organism for studying this question. In this paper, we focus on the invariant
connection structure and spatial arrangement of the neurons comprising the
somatic neuronal network of this organism to understand the key developmental
constraints underlying its design. We observe that neurons with certain shared
characteristics - such as, neural process lengths, birth time cohort, lineage
and bilateral symmetry - exhibit a preference for connecting to each other.
Recognizing the existence of such homophily helps in connecting the physical
location and morphology of neurons with the topological organization of the
network. Further, the functional identities of neurons appear to dictate the
temporal hierarchy of their appearance during the course of development.
Providing crucial insights into principles that may be common across many
organisms, our study shows how the trajectory in the developmental landscape
constrains the eventual spatial and network topological organization of a
nervous system.
