concentrations in the creature's body of certain chemical com- 

 pounds. Those concentrations, and thus the state of the drive, are 

 determined by how much food the creature has collided with during 

 recent seconds, and absorbed through its outer membrane. 



If the internal chemical reactions detect that the food supply is 

 adequate, the flagellum continues its anti-clockwise rotation and the 

 creature continues its forward motion. If the food supply drops be- 

 low the level required for survival, the bacterium tumbles and moves 

 off in another direction. Such a diversion provides no guarantee that 

 the bacterium will now be travelling toward plentiful food, but it's 

 a better tactic than just doggedly staying on course. 



In the case of the bacterium, therefore, the only stimulus is the 

 one provided by its own motion, as it explores its surroundings, and 

 the only response is the feedback from those surroundings, in the 

 form of food the creature hits and ingests. This is just the opposite 

 of a reflex. So the behavior of E. coli must be described in terms 

 of self-paced probing of its surroundings (see fig. 1, right). And the 

 current direction of rotation of its flagellum indicates what it has 

 discovered recently about those surroundings, regarding the local 

 distribution of potential food. Such acquisition of information can 

 usefully be regarded as cognition, in a primitive form admittedly, 

 but cognition nevertheless. 



There will not be room here to discuss the behavior of many other 

 species, but let us consider one at least, namely the honeybee Apis 

 mellifera ligustica. As is well known, individuals of this species can 

 gauge the direction and distance to a discovered source of nectar, 

 and inform their hive-mates of this data, through their famous wag- 

 gle dance. Karl von Frisch (1974) believed that their distance-mea- 

 suring prowess stems from an ability to (unconsciously) record the 

 amount of energy expended during the forage, but Mandyan Srini- 

 vasan, Shaowu Zhang, Monika Altwein and Jiirgen Tautz (2000) 

 have shown that the faculty has a different source. They made bees 

 fly through a short tube whose inner surface was decorated with a 

 pattern resembling a distorted chess board. Studying the subsequent 

 waggle dance, the investigators noted that the bees were signaling 

 a distance of several tens of meters, whereas a cache of nectar had 

 been placed at the tube's other end, a mere meter away. The pattern's 



