INTRODUCTION: Environmental factors play a major role in neurodevelopment and diseases. Numerous classes of receptors sense environmental factors and trigger cellular signaling in diverse cellular and anatomical regions. Despite the fundamental importance of environment factors for cells, cell theory lacks an environment-centric hypothesis.

AIM(S): The goal was to develop a new hypothesis about the environment that would supplement the cell theory.

METHOD(S): Scientific literature on the role of environmental factors in diverse organisms was read critically. Diverse proteins—allosterically regulated ones as potential receptors, competitively inhibited ones as proto-receptors—were considered responsive to environmental factors.

RESULTS: A Circumiacentium hypothesis—that all cells are limited by their environment—was proposed. Several potential experiments to falsify this hypothesis were also proposed.

CONCLUSIONS: If the Circumiacentium hypothesis withstands falsification, it will supplement cell theory by providing a novel framework for understanding the environment's role in cells. It also holds relevance for neurodevelopmental disorders and neurodegenerative diseases.