TRACKING VARIABLE ENVIRONMENTS - THERE IS MORE THAN ONE KIND OF MEMORY

Three kinds of memory help herbivores track changes in the environment . The first is the collective memory of the species with genetic instr uctions that have been shaped by the environment through millennia. Th is includes skin and gut defense systems. Auditory and visual stimuli and sensations of pain impinge upon the skin defense system that evolv ed in response to predation. The taste of food and the sensations of n ausea and satiety are an integral part of the gut defense system that evolved in response to toxins and nutrients in plants. The second kind of memory in social mammals is represented by the mother, a source of transgenerational knowledge, who increases efficiency and reduces ris k of learning about foods and environments. The third kind of memory i s acquired by individual experience. Post-ingestive feedback from nutr ients and toxins enables individuals to experience the consequences of food ingestion and to adjust food preference and selection commensura te with a food's utility. The three memories interact, each linking th e past to the present, and collectively shape the present and future o f every individual. Thus, the dynamics of foraging involves appreciati ng the uniqueness of individuals and subgroups of animals, each with t heir own genetic and behavioral history, and recognizing that foraging behaviors may not be stable, optimal, or even predictable in the conv entional sense.