The human brain is limited by its capacity and incapable of memorizing all information. The memory system evolved to give preference to memory information related to maintaining and increasing individual fitness. We have chosen fungi, a heavily neglected area in science education research, to investigate which kind of information about mushrooms will be better retained by secondary school students. Furthermore, we investigated whether information about mushroom toxicity is better retained when presented only orally or in combination with a written text. The research sample consisted of 160 secondary school students from Slovakia. Pretest/posttest experimental between-subject and within-subject design was used to examine research questions. Data were collected through questionnaires (using a Likert response scale). We found that survival-relevant information (i.e., mushroom toxicity) was retained significantly better than survival-irrelevant information (i.e., mushroom naming and occurrence), but there were no differences in recall between the presentation conditions. Unexpectedly, male students retained information about mushroom toxicity significantly better than female students. Our results suggest that information retention by secondary school students in regard to mushrooms that cause serious poisoning is in accordance with evolutionary predictions and can be utilized by science teachers.