Fig. 1

“Natural mechanisms preserve lifelong mental health”. Our genetic program is well adapted to the lifestyle conditions that dominated for the largest part of humans’ life history. Ancient lifestyle was marked by extensive and daily physical activity, alternated phases of fasting and a nutrient-rich diet, sufficient sleep and eustress. Furthermore, survival was critically dependent on extended family bonds, hence went along with a rich social life. The exceptional long postmenopausal period served the purpose of transgenerational generativity, which, according to the grandmother hypothesis, provides the main current explanation for humans’ longevity. Therefore, under these natural conditions, all key physiological systems (immune and cardiovascular function, energy metabolism etc.) positively interact and thereby support key mechanisms like neuronal rejuvenation and adult hippocampal neurogenesis in order to allow the lifelong acquisition of knowledge and to preserve mental health up to high age. For details, please refer to the main text