Double effort: Parental behavior of wild Azara's owl monkeys in the face of twins.

In species of mammals that habitually bear single offspring, like most anthropoid primates, the occurrence of twins is expected to impose considerable energetic costs on the caretakers. The question then arises of how caregivers cope with the potentially increased costs of raising twins. These increased costs should lead to differing developmental rates in twins when compared to singletons, and/or to changes in the caregivers' behavior.

Estrogen augmentation in schizophrenia: a quantitative review of current evidence.

Background: Sex differences in the incidence, onset and course of schizophrenia have led to the hypothesis that estrogens play a protective role in the pathophysiology of this disorder. Several trials have assessed the potential of estrogens in reducing schizophrenia symptoms, showing inconsistent results. This quantitative review summarizes available evidence on the efficacy of estrogens in the treatment of schizophrenia.