Animals 1 Child 1 Humans 1 Male 1 Reproduction 1 Sexual Behavior, Animal 1 Sexual Selection 1 animal 1 article 1 child 1 ecology 1 female 1 fitness 1 grandchild 1 human 1 human tissue 1 life history 1 life history theory 1 long-term mating major clinical study 1 male 1 mating 1 reproduction 1 reproductive ecology 1 reproductive success 1 sexual behavior 1 sexual selection 1 short-term mating 1