The habitat and plant feeding of 64 well-habituated, individually identified adult male and female yellow baboons was studied for 5 years at Mikumi National Park, Tanzania. Variation across the years showed that a study of only one or two years would have been incomplete and misleading. The list of baboon food species obtained from Mikumi is considerably larger and more diverse than any previously reported. One to six plant parts were eaten from each of more than 180 species. The 25 most common tree genera all contained species used for food. Of the 50 most common grass, shrub and herb genera, 93% included plant foods. Using months in which a species was eaten during at least one year of the study, 21 staple species were eaten during a mean of 8.86 months and 7 were eaten in all 12 months. Although many foods were from commonly available plant species, 15 such species were only rarely eaten. The number of parts of a species eaten per month and an estimate of the amounts eaten per month both varied with temperature and rainfall, being lowest near the end of the cool, dry season. There were substantial differences from year to year in the timing and amount of food production of many species; nevertheless, the same broad feeding pattern was repeated in each of the 5 years of the study. Despite yearly variation in food availability, 14 or more staples and other common foods were eaten in any given month. If crops of many of these foods were to fail, a large number of less commonly eaten species could be substituted. Baboons are eclectic feeders that appear to be optimizing their diet by selective feeding from among a wide array of available foods in an ever-changing floristic environment.

Social judgment theory and dissonance theory make different predictions about the effect on attitude change of discrepancies between a person's own position and a persuasive communication. Persuasive messages were given to 144 subjects in a three-factor design having three levels of discrepancy, two levels of source credibility, and two levels of ego-involvement. Dependent measures were attitude change, source credibility change, ego-involvement change, changes in latitudes of acceptance and rejection, and message evaluation. More attitude change occurred for low than for high ego-involvement. Attitude change was an increasing monotonic function of discrepancy for low ego-involvement, and a nonmonotonic function of discrepancy for high ego-involvement. After receipt of the persuasive message, low credible sources increased in authoritativeness and the importance of the low-ego-involvemcnt issue increased. A number of findings, significant beyond the .01 or .001 levels, were opposed to dissonance theory predictions. Most of the data arc consistent with social judgment theory.Among the many variables influencing attitude change, three have come into particularly sharp focus during the past decade: the credibility of the source of a persuasive communication, the role of ego-involvement in attitude change, and the discrepancy between a persuasive message and the attitude of persons upon whom influence is being exerted. These three factors are significant for two important, competing theories of attitude change, social judgment theory and dissonance theory.According to social judgment theory, susceptibility to attitude change depends upon the closeness of discrepant information to an attitudinal anchor. An attitudinal anchor is defined in terms of a latitude of acceptance, that is, all the acceptable positions on an attitude continuum. Similarly, a latitude of rejection consists of all the unacceptable positions.

The spatial organization of progressing baboons is thought to serve a protective function considered important in their adaptation to a terrestrial existence. Progression positions of identified black infants, adult males, and other yellow baboons were determined from repeated samples of troop movements. Spatial positioning by demographic class was similar to that previously found for three troops of anubis baboons living in two different habitats. Such consistency across species and habitats seems unlikely unless it arises from a common genetic background or common ontogenetic stabilizing mechanisms.

Evidence of nonrandom positioning among adult males is crucial for a protection theory of the spatial organization of baboon progressions. In a recent study it was suggested that systematic positioning of troop members other than mothers and infants is so slight and rare that progressions may be regarded as essentially random. This suggestion depends upon debatable methodological points presumably downgrading previous findings of nonrandom order. Reanalysis of data from this study revealed numerous analytical and statistical problems, as well as serious calculation and other errors, and showed that the findings are consistent with results of the present and previous research. Adult males tended toward the front or back of progressions, a tendency which was intensified in potentially dangerous situations. Dominant males were disproportionately more often frontward and subordinate males rearward. Nonrandom order, which was found for a variety of circumstances at high levels of statistical significance, was unusually general in that it occurred in 6 studies, 7 troops, 2 species, and 5 locations. Such generality is consistent with a protection theory postulating phylogenetic underpinnings of a sociospatial organization which allows an advanced primate to adapt to terrestrial coexistence with predators.

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Ageing and social status effects on reproductive condition are examined in 106 wild female baboons from 1974 to 1997. The mean duration of each reproductive state (follicular and luteal phase components, pregnancy and lactation) was examined per female, using a repeated measures analysis of variance across each of four age classes (3-6, 7-10, 11-14, and 15-20+ year olds) and dominance rank quartiles. The sex-skin swelling portion of the follicular phase increased whereas the fully swollen portion decreased in duration with advancing age and with low dominance rank. The detumescing portion of the luteal phase increased with advancing age, being most pronounced in lowest ranking females. The number of cycles to conception decreased with age, with no dominance rank effect. However, owing to variation in lactation duration, the interbirth interval was unaffected by age but was shorter in high ranking females. The miscarriage rate was unaffected by age but increased as female rank declined. Age and rank effects became significantly more pronounced in response to a crash in the study population between 1987 and 1993. In conclusion, age- and rank-related reproductive changes in baboons, like those in humans, appear to represent attempts to compensate endocrinologically for accelerated ovarian atresia and increased environmental hardship.

ABSTRACT. Empirical analyses of techniques for observing spontaneous social behavior have been guided by implicit assumptions about the techniques' validity, reliability, and comparability. The actual duration and actual frequency of a behavior have been used as intuitive standards of validity. Noncorrespondence among absolute values obtained from these measures and from one-zero scores has been taken to mean that one-zero scores are invalid. An analysis of macaque and gelada grooming relationships demonstrated how unjustified assumptions about absolute values can affect conclusions. A statistical comparison of four types of observation scores, and a multiple-regression analysis of one-zero scores, contradicted assumptions made previously about reliability and validity. The four methods were comparable and all were reasonably accurate.

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