[1] Cell division asymmetries have appeared alongside the evolution of complex developmental processes.
While bacteria were historically considered symmetric simple cells, this idea has been overturned by novel technology and observation techniques.
Asymmetrical growth aids in determining the age of bacteria, because it gives rise to an old pole, or region of inert cell wall material found at the ends of a rod-shaped bacterial cell.
Following the "old pole" of the cell wall material allows an observer to create a bacterial lineage.
[2] Conditional asymmetry is well defined in the case of endospore formation, which is triggered by stressful environmental conditions such as increased heat, pH change, and nutrient depletion.