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Spontaneous interactions over fruits and vegetables were observed in a captive group of Cebus apella. The group lacked fully grown males; 3 adult females dominated the remaining 11 individuals, most of which were adolescents and late juveniles. Apart from expressions of interest and unsuccessful attempts to claim food, interactions over food included two types of interindividual food transfer: forced claims (i.e., involuntary transfers) and peaceful sharing. These two categories represented 7.2% and 20.3% of 3,389 observed food interactions, respectively. Sharing of food was subdivided into four categories; the most frequent category was the collection of discarded food items from within reach of the possessor, and the least frequent was active giving of food items by the possessor. The voluntary nature of food transfers was further investigated in an experiment in which two monkeys were placed in adjacent cages with a wire-mesh partition between them. One subject received food; the other did not. Although this setup made it easy for possessors to prevent food transfers, sharing occurred in all 18 tests on different combinations of individuals. In 10 of the tests, possessors were observed to actively push food through the mesh partition to their partner. © 1993 Wiley-Liss, Inc.

The effects of social dominance on male mating behavior and paternity in a troop of rhesus monkeys (macaca mulatta) were examined. A wild-caught troop of monkeys, captured in India in 1972, has been monitored in captivity for eight years. Some animals have been culled from this troop, but no new animals have been added except through births. The social structure of the troop has remained fairly stable over the eight years, although the number of adult males at any given time has ranged from four to ten. We blood typed 77 offspring born between 1973 and 1980 that survived to two months of age and determined paternity for 48 of them. During the eight-year period, the dominant male sired only 13% to 32% of the offspring, even though he participated in 67% of the observed copulations. In contrast, the second ranking male sired 30% to 48% of the offspring, but participated in only 14% of the observed matings. The frequency and duration of copulation in any one year appeared to reflect a male's rank in the dominance hierarchy. However, in all but one year of our study, the largest number of offspring were sired, not by the dominant male, but by young males who were second or third in rank. Nevertheless, the dominant male may have a selective advantage because he sires a large number of offspring early in life, and continues to produce offspring over many years. This study demonstrates that observed copulations are imprecise indicators of paternity, and that paternity in any one breeding season is a poor indicator of the genetic structure of a population.

Teeth-baring in a large captive rhesus monkey group (Macaca mulatta) was observed over a 30-month period. Its directional consistency among adults was significantly higher than that of aggression. The unidirectionality was so extreme that the facial display must be seen as a formal status indicator; ie, a signal of which the direction is independent of short-term contextual variation. As such, it seems adapted for communication about the state of the relationship. Formal dominance relationships among adults could be arranged in a hierarchy which approached perfect linearity. Focal observations demonstrated that teeth-baring was associated with withdrawal. It was uncommon among foraging monkeys, perhaps because dominant animals paid less attention to their subordinates in this context. The speed of rank acquisition by young females, in terms of received teeth-baring, was highest among peers and lowest against the group's old matriarchs. The age at which dominance over unrelated adult females was achieved correlated negatively with the amount of affiliative contact with these females. This translates into a positive correlation between bonding and rank establishment, indicating that dominance processes may be indistinguishable from social integration.

Twenty adult female rhesus monkeys (Macaca mulatta) were observed over a three-year period. They lived in a mixed captive group with kinship relations known for three generations. The study’s aim was to test Seyfarth’s [J. theor. Biol. 65: 671–698, 1977] model of rank-related grooming and to investigate two other possible determinants of social bonding, i.e. relative age and the group’s stratification into two social classes. Data on affiliation, coalitions, and social competition were collected by means of both focal observation and instantaneous time sampling. Whereas certain elements of the existing model were confirmed, its explanatory principles were not. Social competition did not result in more contact among close-ranking females (the opposite effect was found), and the relation between affiliative behavior and coalitions was more complex than predicted. Based on multivariate analyses and a comparison of theoretical models, we propose a simpler, more encompassing principle underlying interfemale attraction. According to this ‘similarity principle’, rhesus females establish bonds with females whom they most resemble. The similarity may concern (l)genetical and social background, (2) age, (3) hierarchical position and (4) social class. Effects of these four factors were independently demonstrated. The most successful model assumed that similarity factors influence female bonding in a cumulative fashion.

Of 711 physicians likely to perform artificial insemination by donor surveyed to determine their current practices, 471 responded, of whom 379 reported that they performed this procedure. They accounted for approximately 3576 births by this means in 1977. In addition to treating infertility, 26 per cent of these physicians used the procedure to prevent transmission of a genetic disease, and 10 per cent used if for single women. Donors of semen were primarily from universities, were only superficially screened for genetic diseases, and were then matched phenotypically to the recipient's husband. Most recipients were inseminated twice per cycle. Only 17 per cent of physicians used the same donor for a given recipient, and 32 per cent used multiple donors within a single cycle. Only 37 per cent kept records on children, and only 30 per cent on donors. The identity of donors usually was carefully guarded to ensure privacy and to avoid legal complications.In December 1977 a questionnaire was sent to 711 physicians likely to perform artificial insemination by donor. 379 of the 471 who responded indicated that they performed this procedure, accounting for approximately 3576 births by this means in 1977. In addition to treating infertility, 26% of these physicians used the procedure to prevent transmission of a genetic disease. 10% of the physicians used the procedure for single women. Donors of semen were primarily from universities, were only superficially screened for genetic diseases, and were then matched phenotypically to the recipient's husband. 61.4% of the doctors inseminated women twice per cycle; others did so either once (17%) or 3 times (20.5%). Only 17% of physicians used the same donor for a given recipient, and 32% used multiple donors within a single cycle. Only 37% kept records on children, and only 30% on donors. The identity of donors usually was carefully guarded to ensure privacy and to avoid legal complications. On the basis of the results of this survey, the following issues concerning artificial insemination by donor appear most important: 1) the screening of donors for genetic diseases is inadequate; 2) current practices reflect little concern for the possibility of consanguineous matings or other effects of multiple donor use; 3) present records on artificial insemination are woefully deficient; and 4) information concerning artificial insemination is scanty.

Agonistic intervention behavior was observed in captive groups of chimpanzees ( Pan troglodytes ), rhesus monkeys ( Macaca mulatta ), and stumptail monkeys ( M. arctoides ). Reciprocity correlations of interventions were determined while removing from the data the effects of several symmetrical relationship characteristics, that is, matrillineal kinship, proximity relations, and same-sex combination. It was considered likely that if significant reciprocity persisted after controlling for these characteristics, the reciprocity was based on cognitive mechanisms. Statistical significance was tested by means of recently developed matrix permutation procedures. All three species exhibited significant reciprocity with regard to beneficial interventions, even after controlling for symmetrical traits. Harmful interventions were, however, reciprocal among chimpanzees only. This species showed a "revenge system", that is, if A often intervened against B, B did the same to A. In contrast, both macaque species showed significantly inversed reciprocity in their harmful interventions: if A often intervened against B, B rarely intervened against A. Further analysis indicates that the strict hierarchy of macaques prevents them from achieving complete reciprocity. Compared to chimpanzees, macaques rarely intervene against higher ranking group members. The observed contrast can be partially explained on the basis of differences in available space, as indicated by a comparison of indoor and outdoor living conditions for the chimpanzee colony. Yet, even when such spatial factors are taken into account, substantial behavior differences between chimpanzees and macaques remain.

Captive studies can make a unique contribution to primate socioecology by documenting species-typical social dispositions under controlled conditions. Recent theories seek to connect the dominance relationships, group cohesiveness, and feeding ecology of primates. The present study explores the first two aspects by comparing the social organization of rhesus (Macaca mulatta) and stumptail monkeys (M. arctoides). Data were collected over a period of eight years, with five different methods, on three well-established captive groups in identical environments. The groups were found to share one characteristic: a clear-cut, linear formal dominance hierarchy as expressed in teeth-baring displays. The two main study groups (one of each species) differed significantly, however, with respect to nine of eleven behavioral measures. In addition to a previously reported higher frequency of reconciliation in the stumptail group, this group showed (1) more frequent but less severe aggressive behavior, (2) greater symmetry of contests, (3) greater social tolerance, (4) more nonagonistic approaches, and (5) more allogrooming. The differences can be summarized as a contrast in dominance "style," with the stumptails having a more relaxed style and placing greater emphasis on social cohesion than the rhesus monkeys. An egalitarian attitude was also reflected in approach behavior: contacts in the rhesus group were mostly initiated by dominants, whereas contacts in the stumptail group were initiated independent of rank. Comparisons with a second rhesus group, and with published reports, suggest that while some of the observed differences are probably representative of the two species, considerable intraspecific variation does exist, and a more comprehensive program of comparative studies is needed.