Introduction - Are Paramecia Conscious?

Paramecia are single-cell organisms that live in aquatic environments, usually in stagnant, warm water. The ancestors of these tiny life forms, which are about .02 inches long, first appeared on the planet about 1.4 billion years ago. They possess the cytological equivalents of a digestive system, an excretory system, a respiratory system, a musculoskeletal system, an immune system, a reproductive system and a cardiovascular system. Although humans are comprised of over fifty trillion cells, there are no physiological functions in our bodies that are not already pre-existing in the biology of these single-cell organisms. Is it possible that we can find evidence of consciousness in such organisms too?

The Paramecium cytoskeleton is a dynamic three-dimensional structure that fills the cytoplasm body of this organism. The cytoskeleton is comprised of microfilaments, microtubules, and intermediate filaments. These fibers, especially microtubules, provide structure for movement and stability, acting as both muscle and skeleton. Microtubules also provide the mechanics for transferring chromosomes during reproduction and cell division. Cilia, thousands of hair like legs that extend from the body of the Paramecium, are also made out of microtubules. In addition to providing the means of locomotion, cilia act as sensors that collect information about the organism’s environment. The cytoskeleton and the cilia act as the Paramecium’s “computer” gathering, processing, storing and transferring information.

There is a body of evidence that indicates that these little hairy animals learn. For example, a number of studies have observed Paramecia swimming and escaping from capillary tubes. Test results showed that with practice, they took successively less and less time to escape, indicative of a learning mechanism. Many other experiments suggest Paramecia can learn to swim in patterns and through mazes and have a short-term memory, although some of these behaviors depend on their environment. They learn very quickly to retreat from their enemies and to snuggle with their lovers.

If neurons are responsible for learning in multi-celled animals, it is hard to explain how a one-celled animal with no neurons can learn. Dr. Stuart Hameroff, an anesthesiologist and emeritus professor at the University of Arizona who has been working on the problem of explaining consciousness since the 1970s, visualizes Paramecia having tiny biological machines inside their body that seem to “know” exactly what to do. According to Hameroff, "A single celled Paramecium swims around. It finds food. It finds a mate [if necessary] It has sex. It can learn. It can avoid predators. It can avoid obstacles. It's one cell. It does it with microtubules." Microtubules are not just common to single celled organisms. They are also found as the internal structure of neurons in human brains. In his book “Ultimate Computing”, Hameroff suggests that these sub neuronal cytoskeleton components are the basic units of information processing in biological tissue rather than neurons.

If we can define consciousness as the collection and processing of information that makes a difference; then, in its simplest form, we can say the Paramecium has this ability.