Do cells have cognitive worlds?

Dr. Predrag Slijepcevic argues that "these creatures, the cells that we ignore, actually have very, very rich cognitive worlds." In the second week of Biocivilisations, our online course, we learn about the consciousness and sentience of creatures too small for our eyes to see. Humans were not the first engineers in nature: bacteria were. How did they build colonies, engineer cities, right under our noses? Find out more in this clip.