Wallisen Tadashi Hattori

Male and female breeding strategies in a cooperative primate.

Marmosets are cooperative breeders organized as extended family groups, but breeding is generally restricted to a single pair. Breeding competition is fierce in female marmosets; males, on the other hand, show low levels of intragroup aggression. We investigated male and female breeding strategies and the resulting reproductive output in 9 wild groups. Reproductive output, tenure of breeding animals, identification of the breeding system, breeding position replacements, migration and infanticide were recorded; also, we recorded grooming and aggression. Replacement of the breeding male or female was observed on nine occasions. On four occasions, the son of the breeding male inherited the breeding post, but we never observed inheritance of a breeding post by a daughter. Mostly, females attained a breeding post by immigrating to a group that had a breeding vacancy. Our results showed that Callithrix jacchus males and females use different strategies to attain a breeding position and maintain it for as long as possible. These strategies prolong the tenure of the breeding position, which is the best way to produce a large number of offspring. This article is part of a Special Issue entitled: Neotropical Behaviour.

Why do women not prefer much older men? a hypothesis based on alterations in male reproductive physiology related to increased age

Evolutionary Psychology studies suggest that women prefer slightly older or similarly aged partners, although to date few hypotheses have been put forth to explain this pattern of choice. Several recent studies have shown changes in male reproductive parameters as a result of increased age. In the current review of medical literature, we found evidence that much older men are more likely to be infertile, women with much older partners are more likely to experience problems during pregnancy, and children of much older men are more likely to have genetic abnormalities. Based on these findings, we suggest that reproducing with much older men does not represent the best reproductive option for women, which would explain the female preference for only slightly older or similarly-aged mates.

Comer ou não comer, eis a questão: diferenças de gênero na neofobia alimentar

A coated abrasive article having carbon black aggregates incorporated into the construction thereof, in a concentration sufficient to reduce or eliminate the buildup of static electricity during its use.

Female expectations on romantic market in a sample of Brazilian and American women.

This study explored undergraduate women’s mating-market expectations in Brazil and the United States. Participants (n = 387) were shown descriptions of hypothetical stimulus females that were varied to yield all combinations of 2 levels (high/low) of 3 attributes (physical attractiveness/social skills/social status). They subsequently rated each stimulus female on 9 traits, and each stimulus female’s likely preferred long-term mating partner on the same set of 9 scales. Ratings of stimulus females paralleled their descriptions of each positive characteristic, substantially raising ratings on its 3 related traits but also showed substantial halo effects of positive descriptions, increasing the ratings of most unrelated traits. However, women with lower social skills are rated as having better financial prospects, and (only in Brazil) lower social-status women are rated as having more attractive bodies. Likewise, participants deemed that the stimulus would match their preferred partners more on related than unrelated traits, but each of the 3 positive traits also significantly raised all 6 of their unrelated traits. The strongest unrelated effect size was between the stimulus female’s physical attractiveness and her prospective partner’s financial status; this effect was significantly stronger in the American sample. This study shows that women expect positive assortative mating in long-term relationships and that desirable traits are not expected to vary independently. Finally, of the 54 characteristic/trait pairings examined, a large number showed significant sample (United States/Brazil) differences and even more showed significant pairing × sample interactions, suggesting nontrivial cultural and/or facultative influences.

Adult criticism and vigilance diminish free riding by children in a social dilemma

In cooperative situations, individual interests can be in conflict with those of the group, creating a social dilemma in which one must choose whether to cooperate or not. Sensitivity to social stimuli is an important factor influencing cooperative behavior in such dilemmas. The current study investigated the influence of verbal feedback and vigilance by adults on childrens donating behavior in a public goods game. The participants were 739 public school children, between 5 and 12 years of age, who were divided into 34 groups. Each group was assigned to one of four experimental conditions: control, positive feedback (praise), negative feedback (criticism), or vigilance. Participants then played eight rounds of the game. The childrens donations were greater in the feedback and vigilance conditions, but the effects were mediated by age and rounds. The results are most likely related to concerns about reputation, which tend to become stronger with age. Older children are better at self-presentation and understanding social norms. Thus, compared with younger children, they seemed more concerned with appearing to be generous, but only when they could get credit for it. Nevertheless, childrens donations still decreased across the rounds. Although adult vigilance and feedback influence childrens cooperation among peers, other mechanisms are necessary to stabilize their behavior over time.

Intra-sex Variation in Human Mating Strategies: Different People, Different Tactics

Abstract Several studies have demonstrated that men and women exhibit different romantic preferences, which align with the patterns predicted by sexual strategies theory. It is also assumed that the mate’s value is a central factor in determining an individual’s sexual strategy. Thus, the current study was developed to investigate whether intra-sex variation exists in the ideal romantic preferences of both genders and whether these preferences are associated with self-perception. To investigate these questions, cluster analyses were performed on the descriptions of ideal mates for short- and long-term relationships given by 366 Brazilian undergraduates (145 men and 221 women). Subsequently, comparisons were made between the lists of self-perceived attributes related to reproduction generated by the resulting groups. The results suggest that males and females use different mating tactics for short-term mating and that males use different tactics for long-term mating. Among men, the mating tactics observed seem to be related to male mate value and their tactics changed when they described ideal short- and long-term partners. Women’s results showed different preference patterns in short-term assessments but minor differences were observed between them in terms of female mate value. For long-term relationships, female patterns were less distinct, indicating a single preference pattern. These findings indicate that a number of different tactics may be clustered together in investigations that address ideal preferences, and that studies of mate preferences must consider individual self-perceptions.