Beyond aggression: Androgen-receptor blockade modulates social interaction in wild meerkats

In male vertebrates, androgens are inextricably linked to reproduction, social dominance, and aggression, often at the cost of paternal investment or prosociality. Testosterone is invoked to explain rank-related reproductive differences, but its role within a status class, particularly among subordinates, is underappreciated. Recent evidence, especially for monogamous and cooperatively breeding species, suggests broader androgenic mediation of adult social interaction. We explored the actions of androgens in subordinate, male members of a cooperatively breeding species, the meerkat (Suricata suricatta). Although male meerkats show no rank-related testosterone differences, subordinate helpers rarely reproduce. We blocked androgen receptors, in the field, by treating subordinate males with the antiandrogen, flutamide. We monitored androgen concentrations (via baseline serum and time-sequential fecal sampling) and recorded behavior within their groups (via focal observation). Relative to controls, flutamide-treated animals initiated less and received more high-intensity aggression (biting, threatening, feeding competition), engaged in more prosocial behavior (social sniffing, grooming, huddling), and less frequently initiated play or assumed a ‘dominant’ role during play, revealing significant androgenic effects across a broad range of social behavior. By contrast, guarding or vigilance and measures of olfactory and vocal communication in subordinate males appeared unaffected by flutamide treatment. Thus, androgens in male meerkat helpers are aligned with the traditional trade-off between promoting reproductive and aggressive behavior at a cost to affiliation. Our findings, based on rare endocrine manipulation in wild mammals, show a more pervasive role for androgens in adult social behavior than is often recognized, with possible relevance for understanding tradeoffs in cooperative systems

Economic Effects of Taxing Different Organizational Forms under a Dual Income Tax a

This paper analyzes the economic effects of different income splitting rules for closely held corporations and sole proprietorships/partnerships in a tax system with a dual income tax. We conclude that the tax rules for closed corporations offer roughly the same cost of capital as for widely held corporations. Compared to corporate firms, the cost of capital is lower for sole proprietorships/partnerships, because the income-splitting rules both neutralize the impact of the high labor income tax and avoid the two-tier taxation on the corporate form of organization. Adding risk to the model shows that closely held corporations have a lower cost of capital than would be the case without income-splitting rules. a The views expressed in the paper do not necessarily reflect those of the Swedish Ministry of Finance or th

Exercise and the regulation of energy intake

Energy balance is the resultant of ingested calories and energy expenditure and is generally maintained within narrow limits over prolonged periods. Exercise leads to an increase in energy expenditure which is, in the long-term, counteracted by increased energy intake. Evidence for this comes from a study in voluntarily running female rats that increased their daily food intake to 130% of the sedentary controls. In contrast, when considered on a short-term basis, exercise will suppress food intake to prevent a potentially dangerous disruption of energy substrate homeostasis. Studies in permanently cannulated rats submitted to a test meal and 2 hrs swimming reveal that both food intake and exercise lead to increases in glucose and free fatty acid (FFA) levels in the blood. These changes in glucose and FFA, combined with the exercise-induced alteration in among others glucagon, corticotropin releasing hormone (CRH) and body temperature, may lead to the short-term anorexic effect of exercise.

European Union Import Quotas on Chinese Textile and Clothing Exports in 2005: A Panic-Driven Commission or Rational Explanations?

import quotas, European Union, textiles, clothing, China, D72, F14, F53,