Stephen Phillip Easley

The Locomotor Behavior of Callicebus brunneus and Callicebus torquatus

This study presents data on the positional behavior of Callicebus torquatus and Callicebus brunneus collected from two different localities in Peru. C. brunneus primarily utilizes short-distance, bounding leaps, while C. torquatus relies predominantly on quadrupedal walking. Both species utilize small, horizontal and terminal branches more than any other substrate class. We relate the differences in locomotor behaviors between the two species to their utilization of different forest levels. C. brunneus tends to reside in the understory and brush layer forest levels. These more discontinuous strata necessitate higher frequencies of short-distance leaping. C. torquatus occupies the more continuous, interconnected canopy level, and much of its food is found in this level. Comparisons with other species show that Callicebus spp. locomote along smaller-sized, horizontal branches using quadrupedal progression and leaping.

Is Lipsmacking an Indicator of Social Status in Baboons

Lipsmacking is performed by many Old World monkey species, and some studies of baboons and macaques suggest that lipsmacking may be associated with social status. We studied 60 adult anubis baboons (Papio cynocephalus anubis) for 18 months, measured social status and the rate of lipsmacking, and used these data to test the hypothesis that lipsmacking is related to social status. Our results indicate that social status and lipsmacking were not significantly correlated for either males or females. Analysis of lipsmacking in relation to social class (high vs. low) showed no significant difference between status classes for either sex. Lipsmacking was, however, found to be positively associated with affinitive behaviors. These results suggest that baboon lipsmacking provides positive social communication independently of social status.

Training adaptations of baboons to light and moderate treadmill exercise

We evaluated training adaptations by 18 baboons (Papio cynocephalus anubis) to low and moderate quadrupedal walking exercise on a motorized treadmill. Moderate training produced 47% increases in lactate threshold, 63% increases in muscle citrate synthetase activity, increases in percentage of Type IIc muscle fibers, and reduced plasma insulin concentrations. Low training produced only reduced plasma insulin concentrations. Our results indicate that the baboon response to exercise training was similar to that of Homo sapiens, and dependent on exercise intensity.

Studies on the Effects of 60-Hz Electric and Magnetic Fields on Neuroendocrine Circadian Rhythmicity in Nonhuman Primates

Wilson et al. (1981, 1983, 1986) demonstrated that exposure of rats to electric fields for 3 weeks both reduces, by about 50%, the amplitude of the nocturnal peak in melatonin production by the pineal gland and delays, by about 2 hours, the time of peak melatonin production. Semm (1983), Welker et al. (1983), and Olcese and Reuss (1986) have demonstrated magnetic field effects on pineal melatonin synthesis in rodents.