role in "explaining female social dominance" in ring-tailed lemurs, as androgens are associated with aggressive behavior in young females. Females that were "exposed to greater concentrations of maternal [androstenedione] late in fetal development were less likely to be aggressed against postnatally, whereas females that were...exposed to greater concentrations of maternal [testosterone]...were more likely to receive aggression postnatally." Dominance rank in female chimpanzees is correlated with reproductive success. Although a high rank is an advantage for females, clear linear hierarchies in female chimpanzees have not been detected. In "masculinized" female mammals like the spotted hyena (Crocuta crocuta), androgens (i.e. specifically, androstenedione and testosterone) are "implicated in the organization and activation of...nonreproductive behavioral traits, including aggression, social dominance, rough-and-tumble play, and scent marking" For aggressively dominant female meerkats (Suricata suricatta), they have "exceptionally high concentrations" of androgens, "particularly during gestation". Birds The concept of dominance, originally called "pecking order", was described in birds by Thorleif Schjelderup-Ebbe in 1921 under the German terms Hackordnung or Hackliste and introduced into English in 1927. In his 1924 German-language article, he noted that "defense and aggression in the hen is accomplished with the beak". This emphasis on pecking led many subsequent studies on fowl behaviour to use it as a primary observation; however, it has been noted that roosters tend to leap and use their claws in conflicts. Wild and feral chickens form relatively small groups, usually including no more than 10 to 20 individuals. It has been shown that in larger groups, which is common in farming, the dominance hierarchy becomes less stable and aggression increases. Dominance hierarchies are found in many species of bird. For example, the blue-footed booby brood of two chicks always has a dominance hierarchy due to the asynchronous hatching of the eggs. One egg is laid four days before the other, and incubation starts immediately after laying, so the elder chick is hatched four days before the younger chick and has a four-day head start on growth. The elder, stronger chick almost always becomes the dominant chick. During times of food shortage, the dominant chick often kills the subordinate chick by either repeatedly pecking or by ousting the younger chick from the nest. The brood hierarchy makes it easier for the subordinate chick to die quietly in times of food scarcity, which provides an efficient system for booby parents to maximize their investment. Eusocial insects In insect societies, only one