Previous Experiences and Regularity of Occurrence in Evolutionary Time Affect the Recall of Ancestral and Modern Diseases

Abstract

Human beings have an adaptive memory that adjusts to different threats in the environment; however, we know little about the factors that modulate this plasticity in memory. Using challenges related to disease threats as a research model, we investigated whether the regularity of occurrence and previous experience with diseases would be factors responsible for predicting memory performance. To test the hypothesis that information regarding diseases that affect with regularity over evolutionary time is better remembered, we grouped diseases into chronic and acute. To investigate the hypothesis that information about diseases that affect regularly in the current environment is better remembered, we grouped diseases into high- and low-incidence. Furthermore, to test the hypothesis that information about illnesses from previous experiences is better remembered, we grouped illnesses into experienced and unexperienced by the participants in this study. As an alternative hypothesis, we investigated whether the recall could be influenced by diseases that originated in ancestral environments or are simply explained by regularity and previous experience with diseases. For this purpose, we grouped the acute and chronic diseases into ancestral and modern. Information about illnesses was presented to university students through fictional stories, followed by an unexpected memory test to identify the best-remembered information. We found that information about diseases that affect regularly over evolutionary time (acute) and from previous experiences was remembered more, whereas ancestral and regular diseases in the current environment (high incidence) were remembered less. This was possibly because diseases that affect humans regularly over evolutionary time spawned greater earlier experiences, increasing people’s perception of risk and facilitating its evocation in memory. In addition, regular diseases in human evolutionary history may have generated greater selective pressure on memory, contributing to a better retention of information. Human beings have developed an adaptability to deal with different environmental adversities, favoring those challenges in memory that affect them regularly and from previous experiences and not necessarily those challenges that refer only to threats from ancestral environments.