Principal components analysis of physical growth in savannah baboons

Segmental morphometrics of the olive baboon (Papio anubis): a longitudinal study from birth to adulthood

The linear dimensions and inertial characteristics of the body are important in locomotion and they change considerably during the ontogeny of animals, including humans. This longitudinal and ontogenetic study has produced the largest dataset to date of segmental morphometrics in a Catarrhini species, the olive baboon. The objectives of the study were to quantify the changes in body linear and inertial dimensions and to explore their (theoretical) mechanical significance for locomotion. We took full-body measurements of captive individuals at regular intervals. Altogether, 14 females and 16 males were followed over a 7-year period, i.e. from infancy to adulthood. Our results show that individual patterns of growth are very consistent and follow the general growth pattern previously described in olive baboons. Furthermore, we obtained similar growth curve structures for segment lengths and masses, although the respective time scales were slightly different. The most significant changes in body morphometrics occurred during the first 2 years of life and concerned the distal parts of the body. Females and males were similar in size and shape at birth. The rate and duration of growth produced substantial size-related differences throughout ontogeny, while body shapes remained very similar between the sexes. We also observed significant age-related variations in limb composition, with a proximal shift of the centre of mass within the limbs, mainly due to changes in mass distribution and in the length of distal segments. Finally, we observed what we hypothesize to be 'early biomechanical optimization' of the limbs for quadrupedal walking. This is due to a high degree of convergence between the limbs' natural pendular periods in infants, which may facilitate the onset of quadrupedal walking. Furthermore, the mechanical significance of the morphological changes observed in growing baboons may be related to changing functional demands with the onset of autonomous (quadrupedal) locomotion. From a wider perspective, these data provide unique insights into questions surrounding both the processes of locomotor development in primates and how these processes might evolve.

Bipedality from locomotor autonomy to adulthood in captive olive baboon (Papio anubis): Cross-sectional follow-up and first insight into the impact of body mass distribution

OBJECTIVE

Despite that the biomechanics of standing and walking bipedally has been extensively studied in nonhuman primates, the morphological features that may constrain, or facilitate, the control of balance and thus of the spontaneous occurrence of bipedal behavior are poorly known. We aim to test the relationship between body mass distribution and bipedal behavior using a nonhuman primate species, the olive baboon, Papio anubis, raised in captivity.

MATERIALS AND METHODS

We collected quantitative data on the frequency and duration of bipedalism together with morphometrics on a sample of 22 individuals. We used ontogenetic changes as a natural experiment that provides insights into the impact of morphology. Specifically we focus on 1) quantifying how body mass distribution changes from infancy to adulthood in baboons; and 2) whether the different patterns of mass distribution influence the behavioral variables, i.e., a) the frequency and b) the duration of bouts of bipedal behavior realized in different activity contexts.

RESULTS

With regard to assisted bipedal behaviors, the duration and frequency of bouts of standing, contrary to walking, are significantly related to age. With regard to unassisted bipedal behaviors, no correlation to age is observed; the bout duration of walking is strongly correlated to body mass and mass distribution, contrary to the frequency of walking as well as the bout duration and frequency of bipedal standing.

DISCUSSION

Our results suggest a close relationship between the pattern of mass distribution and the mechanism of balance control in the spontaneous bipedal walking of baboons. The mechanical effects of the pattern of mass distribution on the ability to perform bipedally in extant nonhuman primates are discussed in the context of the evolution toward habitual bipedalism.

Seasonal and reproductive variation in body condition in captive female Japanese macaques (Macaca fuscata)

The geographic distribution of Japanese macaques includes populations with the most northern range of any primate species. Not surprisingly, females of this species are characterized by physiological adaptations and unique fat deposition mechanisms that facilitate their survival through the sometimes-harsh seasonal conditions of temperate climates, as well as sustaining the metabolic costs of mating, pregnancy, and lactation. Here, we explore the relationship between nutritional status, seasonality, and reproductive status using anthropometric and leptin measures from 14 captive female Japanese macaques. No seasonal patterns were found in the levels of leptin, but there were differences between seasons in anthropometric measures, specifically between the beginning and the end of the mating season. Females gained weight and accumulated energy reserves in fall to prepare for mating activity, and to survive the severe conditions of winter, which is also the period of gestation if pregnancy occurs. Lactating females had larger total skinfolds relative to nonlactating individuals, and females with older babies at the beginning of the mating season had larger abdominal skinfolds than did those with younger babies. There was a relationship between the likelihood of conception and nutritional status, with females that conceived during one mating season being in better condition at the end of their previous mating season. Together, these results suggest that, even in captive settings, seasonal breeding has a cost on the energetic demands of mating, and that higher condition (i.e. fatter) females could afford the demands of lactation and reproduced more rapidly.

Ontogeny of limb mass distribution in infant baboons (Papio cynocephalus)

Primates have more distally distributed limb muscle mass compared to most nonprimate mammals. The heavy distal limbs of primates are likely related to their strong manual and pedal grasping abilities, and interspecific differences in limb mass distributions among primates are correlated with the amount of time spent on arboreal supports. Within primate species, individuals at different developmental stages appear to differ in limb mass distribution patterns. For example infant macaques have more distally distributed limb mass at young ages. A shift from distal to proximal limb mass concentrations coincides with a shift from dependent travel (grasping their mother's hair) to independent locomotion. Because the functional demands placed on limbs may differ between taxa, understanding the ontogeny of limb mass distribution patterns is likely an essential element in interpreting the diversity of limb mass distribution patterns present in adult primates. This study examines changes in limb inertial properties during ontogeny in a longitudinal sample of infant baboons (Papio cynocephalus). The results of this study show that infant baboons undergo a transition from distal to proximal limb mass distribution patterns. This transition in limb mass distribution coincides with the transition from dependent to independent locomotion during infant development. Compared to more arboreal macaques, infant baboons undergo a faster transition to more proximal limb mass distribution patterns. These results suggest that functional demands placed on the limbs during ontogeny have a strong impact on the development of limb mass distribution patterns.

Serum leptin levels in wild and captive populations of baboons (papio): implications for the ancestral role of leptin

Leptin has emerged as the major lipostat, regulating adiposity by affecting feeding behavior and thermogenesis. Leptin levels in normal-weight Western humans and in captive rodents are 5-15 ng/ml. But evidence suggests that these levels are abnormally high and that leptin may have evolved as a more general metabolic signal, with its most robust effects at lower levels. If this is true, then wild, healthy animal populations should have lower levels of leptin than captive populations and Western Man. We examined leptin levels in wild, East African populations of baboons (Papio anubis, P. hamadryas, and anubis/hamadryas hybrids). Serum leptin levels averaged less than 1 ng/ml, and no differences occurred in leptin levels among the species. In wild baboons, serum leptin levels were highest in the youngest baboons, with a trend toward an inverse relation between dental age and serum leptin levels. In comparison, captive baboons had levels about three times higher than wild baboons, with a clear inverse relation between age and leptin levels. These results support the view that leptin evolved to be effective at low levels.

Individual variation in the growth of captive infant gorillas

Serial anthropometric data were obtained during the first year of life of six nursery-reared infant gorillas in the Columbus (Ohio) Zoo. Two of the infants are likely to be monozygotic twins as determined by DNA analysis. Growth curves were fitted to serial measures of cephalo-thoracic-abdominal length, arm length, leg length, head circumference, upper arm circumference, and weight from each gorilla, to describe individual patterns of variation in skeletal growth and body composition. Growth in skeletal measures tended to be curvilinear to varying degrees over the first year of life. Body composition varied more than skeletal measures throughout the first year as a consequence of individual health status. Individual growth and body composition variations appear to reflect both genetic and environmental influences in this small sample of captive infant gorillas.

Heterochrony and sexual dimorphism in the pigtailed macaque (Macaca nemestrina)

Somatic growth is not a simple linear process with a constant rate of growth. The most successful attempts to quantify growth as a function of age or size have employed nonlinear techniques. Sexual dimorphism of primate growth, weight vs. age, was examined using nonlinear models with Sirianni and Swindler's ([1985] Growth and Development of the Pigtailed Macaque, Boca Raton, FL: CRC Press) growth data on the pigtailed macaque (Macaca nemestrina). The best fit of several exponential growth models was the Gompertz curve: Weight = a*e-b*e-K*age Different multiple phase models were also fit, where each phase represents a distinct exponential component. The two-phase models proved to be the best (R2 = .0.84 for females, 0.91 for males), suggesting that there are two growth spurts, one in infancy and one at puberty. The timing of the beginning and end of the first spurt is the same in males and females, but the rate, and value of the asymptote for this phase, is greater in males. The timing of the second spurt is earlier, and the rate of growth for this spurt is smaller in females than males. The sexual dimorphism in these species is not a simple rate change, but a complex interaction of timing and rate over the entire period of growth. It would be impossible to separate these entities with a linear, polynomial, or single-phase model of the data. While these data and results complement much of the existing work on adult dimorphism, they also emphasize the vital role that ontogenetic data have in elucidating the underlying evolutionary mechanisms that generate sexual dimorphism.

Neonatal nutrition and longitudinal growth from birth to adolescence in baboons

Clinically normal baboons (Papio cynocephalus anubis [Kingfjdon, 1971]) were used in an experiment which (1) examined growth in 48 subjects randomly assigned to three diet treatments (LC = low calorie; MC = medium calorie; HC = high calorie); (2) tested the hypothesis that different amounts of caloric availability during the neonatal period (birth to 16 weeks) had a significant effect on growth and development as measured by weight, crown-rump length, and triceps circumference in the subsequent infant, juvenile, and adolescent periods; (3) evaluated the rate of growth in these subjects; and (4) evaluated the extent to which they were capable of canalization (catch-up and catch-down growth). The LC subjects were fed 40% fewer calories than MC subjects and HC subjects were fed 40% more calories than MC subjects. Early in life baboon growth was influenced by caloric shortages and excesses. Canalization of growth attainment occurred in both the LC and HC infants after preweaning dietary treatments had ceased. This suggested that removal of environmental (caloric) insults allowed growth to be regulated by its genetic component (developmental canalization) and to return to a more normal growth pattern. Catch-up growth of LC infants occurred by 26 weeks. Catch-down growth of HC infants to normal levels occurred by 26 weeks. This indicates that growth canalization can work in both directions (reduction from caloric excess and increase from caloric insufficiency) within the same time frame. Following infancy, there were few significant treatment differences in growth of males, whereas females retain the effects of neonatal dietary treatments throughout the 5-year study.