Louis DiVincenti

The Evolution of Self-Control

Significance Although scientists have identified surprising cognitive flexibility in animals and potentially unique features of human psychology, we know less about the selective forces that favor cognitive evolution, or the proximate biological mechanisms underlying this process. We tested 36 species in two problem-solving tasks measuring self-control and evaluated the leading hypotheses regarding how and why cognition evolves. Across species, differences in absolute (not relative) brain volume best predicted performance on these tasks. Within primates, dietary breadth also predicted cognitive performance, whereas social group size did not. These results suggest that increases in absolute brain size provided the biological foundation for evolutionary increases in self-control, and implicate species differences in feeding ecology as a potential selective pressure favoring these skills. Cognition presents evolutionary research with one of its greatest challenges. Cognitive evolution has been explained at the proximate level by shifts in absolute and relative brain volume and at the ultimate level by differences in social and dietary complexity. However, no study has integrated the experimental and phylogenetic approach at the scale required to rigorously test these explanations. Instead, previous research has largely relied on various measures of brain size as proxies for cognitive abilities. We experimentally evaluated these major evolutionary explanations by quantitatively comparing the cognitive performance of 567 individuals representing 36 species on two problem-solving tasks measuring self-control. Phylogenetic analysis revealed that absolute brain volume best predicted performance across species and accounted for considerably more variance than brain volume controlling for body mass. This result corroborates recent advances in evolutionary neurobiology and illustrates the cognitive consequences of cortical reorganization through increases in brain volume. Within primates, dietary breadth but not social group size was a strong predictor of species differences in self-control. Our results implicate robust evolutionary relationships between dietary breadth, absolute brain volume, and self-control. These findings provide a significant first step toward quantifying the primate cognitive phenome and explaining the process of cognitive evolution.

Inherently analog quantity representations in olive baboons (Papio anubis)

Strong evidence indicates that non-human primates possess a numerical representation system, but the inherent nature of that system is still debated. Two cognitive mechanisms have been proposed to account for non-human primate numerical performance: (1) a discrete object-file system limited to quantities <4, and (2) an analog system which represents quantities comparatively but is limited by the ratio between two quantities. To test the underlying nature of non-human primate quantification, we asked eight experiment-naive olive baboons (Papio anubis) to discriminate between number pairs containing small (<4), large (>4), or span (small vs. large) numbers of food items presented simultaneously or sequentially. The prediction from the object-file hypothesis is that baboons will only accurately choose the larger quantity in small pairs, but not large or span pairs. Conversely, the analog system predicts that baboons will be successful with all numbers, and that success will be dependent on numerical ratio. We found that baboons successfully discriminated all pair types at above chance levels. In addition, performance significantly correlated with the ratio between the numerical values. Although performance was better for simultaneous trials than sequential trials, evidence favoring analog numerical representation emerged from both conditions, and was present even in the first exposure to number pairs. Together, these data favor the interpretation that a single, coherent analog representation system underlies spontaneous quantitative abilities in primates.

Safety and clinical effectiveness of a compounded sustained-release formulation of buprenorphine for postoperative analgesia in New Zealand White rabbits

OBJECTIVE To determine the clinical effectiveness and safety of a compounded sustained-release formulation of buprenorphine, compared with effects of regular buprenorphine, for postoperative analgesia in rabbits. DESIGN Blinded randomized controlled clinical trial. ANIMALS 24 purpose-bred adult male New Zealand White rabbits. PROCEDURES Rabbits received titanium implants in each tibia as part of another study. Immediately prior to surgery, each rabbit received regular buprenorphine hydrochloride (0.02 mg/kg [0.009 mg/lb], SC, q 12 h for 3 days) or 1 dose of a compounded sustained-release formulation of buprenorphine (0.12 mg/kg [0.055 mg/lb], SC) followed by an equal volume of saline (0.9% NaCl) solution (SC, q 12 h for 3 days) after surgery. For 7 days after surgery, rabbits were evaluated for signs of pain by means of rabbit grimace and activity scoring and for adverse effects. RESULTS No significant differences were identified between treatment groups in grimace and activity scores at any point. No major adverse effects were detected for either drug. However, 3 rabbits that received regular buprenorphine had pain scores suggestive of moderate to severe pain by the time dose administration was due (ie, within the 12-hour administration interval). No clinically important differences were detected in intraoperative anesthetic or postoperative recovery variables. CONCLUSIONS AND CLINICAL RELEVANCE Sustained-release buprenorphine administered SC at 0.12 mg/kg was at least as effective as regular buprenorphine in providing analgesia for rabbits following orthopedic surgery without any major adverse effects. This sustained-release formulation represents an important alternative for rabbit analgesia with potential to improve rabbit welfare over existing analgesic standards.

Effects of housing density on nasal pathology of breeding mice housed in individually ventilated cages.

The 2011 edition of the Guide for the Care and Use of Laboratory Animals includes new recommendations for the amount of floor space that should be provided to breeding mice. When pairs or trios of continuously breeding mice are housed in shoebox cages, they may have less than this recommended amount of floor space. High housing densities may adversely affect animal health, for example, by compromising air quality inside the cage. Hence, some institutions are carefully reevaluating the microenvironments of breeding cages. The use of individually ventilated cages (IVCs) to house research mice allows for greater control over the quality of the cage microenvironment. The authors evaluated the microenvironments of shoebox cages in an IVC rack system housing breeding and non-breeding Swiss Webster mice. Ammonia concentrations were significantly higher in cages housing breeding trios with two litters. Histopathologic lesions attributable to inhaled irritants such as ammonia were found in mice housed in breeding pairs and trios. The authors conclude that the microenvironments of cages in an IVC rack system housing breeding pairs and trios may be detrimental to animal health.

COMPARISON OF SELECT HEMATOLOGY AND SERUM CHEMISTRY ANALTYES BETWEEN WILD-CAUGHT AND AQUARIUM-HOUSED LAKE STURGEON (ACIPENSER FULVESCENS)

Hematology and serum chemistry analytes were compared between wild-caught and aquarium-housed lake sturgeon (Acipenser fulvescens) to potentially improve understanding of medical issues in lake sturgeon. Blood samples were taken from 30 lake sturgeon exhibited in 11 institutions in the United States and from 23 experimentally stocked lake sturgeon caught in gill nets in the lower Genesee River in Rochester, New York, USA. For hematology, only segmented neutrophil count was significantly different, with wild-caught fish having a higher number of circulating neutrophils. For clinical chemistry analytes, chloride, uric acid, calcium, phosphate, glucose, aspartate aminotransferase, triglycerides, and creatine kinase were significantly different between the two cohorts. These differences are likely not clinically significant and are attributable to handling stress, variability in environmental parameters, or differences in nutritional status. This is the first report of hematology and serum chemistry values in aquarium-housed lake sturgeon and provides useful reference intervals for clinicians.

Interspecies pair housing of macaques in a research facility

The eighth edition of The Guide for the Care and Use of Laboratory Animals establishes social housing as the ‘default’ for social species including non-human primates. The advantages of social housing for primates have been well established, but small research facilities housing few primates in indoor cages have struggled with social housing as a result of limitations on appropriate housing and availability of compatible monkeys. Here, we report a novel approach to pair housing macaques – crossing species. We have successfully pair housed an intact male rhesus macaque with an intact male cynomolgus macaque, and an adult female rhesus macaque with numerous subadult female cynomolgus macaques. Monkeys in these pairs established dominant–subordinate relationships similar to same-species pairs. Rhesus and cynomolgus macaques can be successfully paired for the purpose of social housing in facilities with limited numbers of monkeys.

Social Behavior of Adult Male New Zealand White Rabbits Housed in Groups or Pairs in the Laboratory

Rabbits are usually singly housed in laboratories, but a new emphasis on providing social housing for social species has prompted exploration of alternative housing for this species. However, a paucity of literature on the social behavior of rabbits in captivity has prevented scientific-based recommendations for appropriate housing. This study involved a descriptive analysis of the social behavior of rabbit bucks in the laboratory in 3 different housing situations: in groups in pens, in pairs in cages, and singly in cages. Based on study observations and the natural history of wild rabbits, bucks engage in affiliative social behaviors, but current caging may not allow for the expression of species-typical behaviors, thereby resulting in continued aggression.