Our findings suggest that in relation to threat, human females have relatively heightened protective reactions compared to males. Females mount stronger immune responses to many pathogens experience a lower threshold to detect, and lesser tolerance of, pain awaken more frequently at night express greater concern about physically dangerous stimuli exert more effort to avoid social conflicts exhibit a personality style more focused on life's dangers react to threats with greater fear, disgust, and sadness and develop more threat-based clinical conditions than males. We searched the literature for physiological, behavioral, and emotional responses to major physical and social threats, and found consistent support for females' responding with greater self-protectiveness than males. We examined whether Campbell's theory has more general applicability by considering whether human females respond with greater self-protectiveness than males to other threats beyond aggression. Anne Campbell's “staying alive” theory proposed that human females produce stronger self-protective reactions than males to aggressive threats because self-protection tends to have higher fitness value for females than males.

Many male traits are well explained by sexual selection theory as adaptations to mating competition and mate choice, whereas no unifying theory explains traits expressed more in females.

Protecting His Mate by E.A. Reynolds