Linda D. Wolfe

Microscopic Characteristics of Hacking Trauma

The purpose of this study was to determine if it is possible to associate machetes, axes, and cleavers with the microscopic parallel striations they leave on the cut surfaces of the bone. Hacking trauma was experimentally inflicted on pig bones using machetes, axes, and cleavers. Negative impressions of both the cut surfaces of the bone and the weapon blades were analyzed using scanning electron microscopy. The results of this investigation indicate that it is possible to correlate a class of hacking weapons to trauma inflicted on bone by these weapons.

Hand preference in the Sifaka (propithecus verreauxi coquereli) during feeding in captivity

The Coquerels sifakas were chosen for this study on hand preference because little is known about handedness in Indriidae. Fifteen Coquerels sifakas were observed at the Duke University Primate Center as they fed on chopped fruit, vegetables, and primate chow. Analysis of age, sex, and hand preference indicated that the adult males both individually and as a group tended toward left-handedness. Adult females as a group did not show a trend in the direction of handedness. However, individual adult females showed consistent right- or left-hand preference. Younger sifakas tended toward ambipreference, suggesting that lateralization of hand preference is gradual, becoming more stable in adulthood. These findings suggest that sex and age may be strong indicators for lateralization of hand preference in Coquerels sifakas.

The potential effects of sex, posture and living condition on lateralized behaviors in ring-tailed lemurs (Lemur catta)

This research explores the effects of posture, sex, and living condition on hand and side preferences of semi-free-ranging, adult ring-tailed lemurs (Lemur catta) housed at the Duke University Primate Center in Durham, NC. Data were collected on 11 adult individuals (five females and six males) during normal daily activities over a ten-week period from May–July 2001. Variables analyzed in this study include unimanual behaviors (i.e., reach, hold, and limb used to start locomotion) and other potentially lateralized behaviors that do not involve handuse (i.e., whole-body turning and tail position). The data were analyzed to investigate potential individual and population level side biases for each behavior; potential sex biases in side preference for each behavior; and for ‘reach’, potential effects of posture (sitting, tripedal stance, or bipedal stance) on individual hand preferences. Additionally, to investigate potential effects of living condition on lateral biases, the data from this study were compared to data collected on the same individual Lemurs living under more restrictive living conditions during the previous year. Largely, as predicted based on available literature, we found that there was a significant sex difference across all hand-use categories and for whole-body turning, and that posture was a significant factor in the expression of hand preference for reaching. Contrary to previous research, the effect of living condition on lateral preferences was minimal, and no side preferences were found at the population level for any of the behaviors analyzed.

Carrying and Hand-use Patterns in Panamanian White-faced Capuchins (Cebus capucinus)

The aim of this project was to examine the potential influence of postural regulation on capuchin hand-use patterns by focusing on tasks that involved the carrying of objects. Two months were spent on Barro Colorado Island, Panama, collecting data on ten white-faced capuchins (Cebus capucicus) (four adult males/six adult females). Over 215 contact hours were spent with the monkeys, and a total of 213 carries were recorded. No hand preference bias at the population level was found for the carry task; and no detectable hand-use patterns for carry were correlated with the weight of the object carried (except a right-hand bias for carrying medium-sized objects), the plane of the monkeys movement, its locomotor pattern, or its height above the ground. Therefore, the results of this study do not support the hypothesis that the need for postural regulation while carrying an object influences hand-use patterns in free-ranging capuchins. Our results are especially important because they are contrary to the results of the only other free-ranging capuchin laterality study conducted to date (Panger, 1998).

Feeding habits of the rhesus monkeys (Macaca mulatta) of Jaipur and Galta, India

Between September 1987 and May 1988, the time budgets of two groups of rhesus monkeys were investigated. One group inhabited an old Observatory which is now a tourist attraction in the center of Jaipur, India. The other group lived in a hilly forest/temple complex on the outskirts of Jaipur known as Galta. Because it was believed that the monkeys of these two different areas ate different proportions of natural and provisioned food, it was expected that they would have different time budgets. To determine differences in time budgets, a combination of census taking and 10-minute interval scan samples were used to collect comparative data. The analysis of the data revealed that there were differences in the time budgets of the two groups — the Observatory monkeys foraged more, moved less, engaged in fewer aggressive acts, and slept less during the day than the Galta group. These differences are mainly attributed to the 1984–1987 drought, site differences in the variety of natural food resources, and the manner in which the monkeys are provisioned.