Does consciousness require a brain? Perhaps, but some have argued instead that all life, or perhaps even all matter, may be conscious or sentient. To tackle this question, we propose to investigate sentience in single-celled organisms. Cells are the most basic unit of life, the level at which life emerges from non-living matter, and can perform behaviors normally associated with cognition. In particular, several reports have shown that single celled organisms (protists) can display apparently purposeful or intentional behavior.
We propose to investigate the two strongest cases: escape behaviors of the giant trumpet-shaped ciliate Stentor roeselii, and hunting behaviors of the blob-like Amoeba proteus. In both cases, the cells employ complex behavioral strategies and seem able to switch to a different strategy when one strategy is not working. Such behavior-switching is a hallmark of intentionality or purposefulness.
To better understand intentionality in these two cell types, we will combine new technologies for probing cell behavior with methods for identifying the molecular pathways that are required to switch behaviors, thus putting the question of intentionality in single cells onto a firm empirical footing.
In the case of human minds, philosophical understanding has been strongly influenced by decades of experimental neuroscience. By knowing some basic facts about how brains work, it has been possible to sharpen many questions concerning the mind. Our goal is to achieve the same transformation for cellular sentience.
We emphasize that this work will NOT answer the question of whether cells are actually sentient, but will at least allow this question to be pursued on the basis of concrete empirical knowledge. By focusing on the cell as an intermediate level of organization between complex brains and basic matter, the impact of this work will be to provide a new basis for thought and investigation into the origins of purposefulness throughout the living world.
