Anorexia nervosa rising prevalence of eating disorders in adolescence are "increase of adipose tissue in girls, hormonal changes of puberty, societal expectations of increased independence and autonomy that are particularly difficult for anorexic adolescents to meet; [and] increased influence of the peer group and its values." Early theories of the cause of anorexia linked it to childhood sexual abuse or dysfunctional families; evidence is conflicting, and well-designed research is needed. The fear of food is known as "sitiophobia", "cibophobia", or "sitophobia" and is part of the differential diagnosis. Other psychological causes of anorexia include low self-esteem, feeling like there is lack of
Fear rats in two different shock situations responded differently, based on instinct or defensive topography, rather than contextual information. Species-specific defense responses are created out of fear, and are essential for survival. Rats that lack the gene stathmin show no avoidance learning, or a lack of fear, and will often walk directly up to cats and be eaten. Animals use these SSDRs to continue living, to help increase their chance of fitness, by surviving long enough to procreate. Humans and animals alike have created fear to know what should be avoided, and this fear can be learned through association with others