males, claiming priority over the cells when males try to use them to place eggs. Costs of being dominant There are costs to being of a high rank in a hierarchical group which offset the benefits. The most common costs to high-ranking individuals are higher metabolic rates and higher levels of stress hormones. In great tits and pied flycatchers, high-ranking individuals experience higher resting metabolic rates and therefore need to consume more food in order to maintain fitness and activity levels compared to subordinates in their groups. The energetic costs of defending territory, mates, and other resources can be very consuming and cause high-ranking individuals, who spend more time in these activities, to lose body mass over long periods of dominance. Therefore, their physical condition decreases the longer they spend partaking in these high-energy activities, and they lose rank as a function of age. In wild male baboons, the highest-ranking male, also known as the alpha, experiences high levels of both testosterone and glucocorticoid, which indicates that high-ranking males undergo higher levels of stress which reduces fitness. Reduced health and longevity occurs because these two hormones have immunosuppressant activity, which reduces survival and presents opportunities for parasitic infestation and other health risks. This reduced fitness due to the alpha position results in individuals maintaining high rank for shorter periods of time and having an overall reduced health and longevity from the physical strain and costs of the position. Interpersonal complementarity hypothesis The interpersonal complementarity hypothesis suggests that obedience and authority are reciprocal, complementary processes. That is, it predicts that one group member's behaviours will elicit a predictable set of actions from other group members. Friendly behaviours are predicted to be met with friendly behaviours, and hostile behaviours are predicted to be reciprocated with similar, hostile behaviours. When an individual acts in a dominant, authoritative manner in a group, this behaviour tends to prompt submissive responses from other group members. Similarly, when group members display submissive behaviour, others feel inclined to display dominant behaviours in return. Tiedens and Fragale (2003) found that hierarchical differentiation plays a significant role in liking behaviour in groups. Individuals prefer to interact with other group members whose power, or status behaviour complements their own. That is to say, group members who behave submissively when talking to someone who appears to be in control are better liked, and similarly individuals who display dominant behaviours (e.g., taking charge,