About
76
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Introduction
I am a broadly trained biological anthropologist with a primary research interest in the comparative neuroanatomy of large brained, social species. I am passionate about community engaged scholarship and as a first generation college student I am an ardent supporter of initiatives that help to expand STEM education. I am from South Africa and completed my graduate training at the University of Witwatersrand, teaching fellowship at UCSB and postdoctoral work at The George Washington University.
Current institution
Additional affiliations
July 2015 - present
Position
- Program Director of the Anatomy Graduate Program
Description
- Histology and quantitative MRI of large brained, social species. NeuroSMART high school STEM program,
August 2016 - November 2016
Position
- Lecturer
Description
- Principles of Anatomy Course BMS 447/547.Co taught along with colleagues at the ISU Veterinary School Drs. Bracha, Lyons, Berg and Starling. I delivered ~14 lectures to the MSc students on human and canine gross anatomy.
February 2016 - present
Position
- Professor (Assistant)
Description
- Contribution to the departments professional and graduate programs - 3D modelling of the canid brain and design of instructional resources - ISU Medical Illustration program and ISU College of Veterinary medicine. Ongoing collaborative research with Dr.Eric Rowe on laterality in domestic artiodactyla.
Education
January 1998 - July 2007
Publications
Publications (76)
The phylogenetic contextualization of human neuroanatomy is crucial for understanding the positive, neutral, and/or negative effects of therapeutic interventions derived from animal models. Here we determined the parcellation of, and quantified, orexinergic (or hypocretinergic) neurons in the hypothalami of humans and several species of primates, i...
Paleoneurology reconstructs the evolutionary history of nervous systems through direct observations from the fossil record and comparative data from extant species. While this approach can provide direct evidence of phylogenetic links among species, it is constrained by the availability and quality of data that can be gleaned from the fossil record...
The evolutionary history of canids and felids is marked by a deep time separation that has uniquely shaped their behavior and phenotype towards refined predatory abilities. The caudate nucleus is a subcortical brain structure associated with both motor control as well as cognitive, emotional and executive functions. We used a combination of three d...
Felids have evolved a specialized suite of morphological adaptations for obligate carnivory. Although the musculoskeletal anatomy of the Felidae has been studied extensively, the comparative neuroanatomy of felids is relatively unexplored. Little is known about how variation in cerebral anatomy of felids relates to species-specific differences in s...
Carnivorans are an important study object for comparative neuroscience, as they exhibit a wide range of behaviours, ecological adaptations, and social structures. Previous studies have mainly examined relative brain size, but a comprehensive understanding of brain diversity requires the investigation of other aspects of their neuroanatomy. Here, we...
Carnivorans are an important study object for comparative neuroscience, as they exhibit a wide range of behaviours, ecological adaptations, and social structures. Previous studies have mainly examined relative brain size, but a comprehensive understanding of brain diversity requires the investigation of other aspects of their neuroanatomy. Here, we...
The orexinergic system, while having several roles, appears to be a key link in the balance between arousal and satiety. In birds, to date, this system has only been examined anatomically in four species, all with brains smaller than 3.5 g and of a limited phylogenetic range. Here, using orexin-A immunohistochemistry, we describe the distribution,...
Cortical folding is related to the functional organization of the brain. The TMF-1 regulated protein (TRNP1) regulates the expansion and folding of the mammalian cerebral cortex, a process that may have been accelerated by the domestication of dogs. The objectives of this study were to sequence the TRNP1 gene in dogs and related canid species, prov...
Employing orexin-A immunohistochemistry, we describe the distribution, morphology, and nuclear parcellation of orexinergic neurons within the hypothalami of an Asiatic lion (Panthera leo subsp. persica), an African lion (Panthera leo subsp. melanochaita), and a Southeast African cheetah (Acinonyx jubatus subsp. jubatus). In all three felids, the cl...
The 2022 meetings of the J.B. Johnston Club for Evolutionary Neuroscience and Karger Workshop in Evolutionary Neuroscience will be held immediately before the annual meeting of the Society for Neuroscience on Thursday, November 10 (the Karger Workshop), and Friday, November 11 (the regular JBJC meeting). Both meetings will take place at the Horton...
Huntington’s disease is an autosomal dominant trinucleotide repeat disorder that causes the progressive degeneration of the basal nuclei. This degeneration leads to clinical symptoms affecting voluntary movement, cognitive impairment, and psychiatric disorders. The patient affected by this disease demonstrates anticipation, meaning that even though...
The pelvis and the skull are the two most utilised skeletal elements to estimate sex from skeletonised remains due to their sexually dimorphic traits. However, as increasingly more fragmented remains have been presented for analyses, other bones and their fragments have now been subjected to analyses for sex estimation. In the skull particularly, t...
The 2021 meetings of the J.B. Johnston Club for Evolutionary Neuroscience and Karger Workshop in Evolutionary Neuroscience is typically held immediately before the annual meeting of the Society for Neuroscience. This year the Karger Workshop will be held on Thursday, November 11. The regular JBJC meeting will be held on Friday, November 12. Due to...
In the current study we examined the number, distribution, and aspects of the neurochemical identities of infracortical white matter neurons, also termed white matter interstitial cells (WMICs), in the brains of a southern lesser galago (Galago moholi), a black-capped squirrel monkey (Saimiri boliviensis boliviensis) and a crested macaque (Macaca n...
To elucidate factors underlying the evolution of large brains in cetaceans, we examined 16 brains from 14 cetartiodactyl species, with immunohistochemical techniques, for evidence of non‑shivering thermogenesis. We show that, in comparison to the 11 artiodactyl brains studied (from 11 species), the 5 cetacean brains (from 3 species), exhibit an exp...
To elucidate causality underlying the evolution of large brains in cetaceans, we examined the brains of 16 cetartiodactyl species for evidence of non-shivering thermogenesis. In comparison to the artiodactyl brain, the cetacean brain exhibits an expanded expression of uncoupling protein 1 (UCP1, UCPs being mitochondrial inner membrane proteins that...
Once considered a hallmark of human uniqueness, brain asymmetry has emerged as a feature widely shared with other mammals, including chimpanzees, one of our closest living relatives. Most notable has been the discovery of asymmetries in homologs of cortical language areas in apes, particularly in the planum temporale (PT), considered a central node...
Once considered a hallmark of human uniqueness, brain asymmetry has emerged as a feature shared with several other species, including chimpanzees, one of our closest living relatives. Most notable has been the discovery of asymmetries in homologues of cortical language areas in apes, particularly in the planum temporale (PT), considered a central n...
Employing a range of neuroanatomical stains, we detail the organization of the main and accessory olfactory systems of the African wild dog. The organization of both these systems follow that typically observed in mammals, but variations of interest were noted. Within the main olfactory bulb, the size of the glomeruli, at approximately 350 μm in di...
The variegated pelage and social complexity of the African wild dog (Lycaon pictus ) hint at the possibility of specializations of the visual system. Here, using a range of architectural and immunohistochemical stains, we describe the systems‐level organization of the image‐forming, non‐image forming, oculomotor, and accessory optic, vision‐associa...
The African wild dog is endemic to sub‐Saharan Africa and belongs to the family Canidae which includes domestic dogs and their closest relatives (i.e. wolves, coyotes, jackals, dingoes and foxes). The African wild dog is known for its highly social behaviour, co‐ordinated pack predation, and striking vocal repertoire, but little is known about its...
The large external pinnae and extensive vocal repertoire of the African wild dog
(Lycaon pictus) has led to the assumption that the auditory system of this unique canid may be specialized. Here, using cytoarchitectural, myeloarchitectural and a range of
immunohistochemical stains, we describe the systems-level anatomy of the auditory system of the...
Over the last 15 years, research on canid cognition has revealed that domestic dogs possess a surprising array of complex socio‐cognitive skills pointing to the possibility that the domestication process might have uniquely altered their brains; however, we know very little about how evolutionary processes (natural or artificial) might have modifie...
An adaptation (in the evolutionary sense) is a feature/trait that serves a particular function in an organism’s environment and improves that organism’s ability to survive (i.e., its fitness).
Evolutionary medicine is a trans-disciplinary field of study aimed at applying evolutionary concepts and thinking to our understanding of medicine.
Human visual neuroscience is an interdisciplinary field of study which seeks to understand the processing of visual information by the eye and brain in humans and provides a well-studied model of how sensory systems enable organisms to interact with their environments.
Definition: Human visual neuroscience is an interdisciplinary field of study which seeks to understand the processing of visual information by the eye and brain in humans and provides a well-studied model of how sensory systems enable organisms to interact with their environments.
Evolutionary medicine is a trans-disciplinary field of study aimed at applying evolutionary concepts and thinking to our understanding of medicine.
The emergence of stone tools represents a significant milestone in hominin evolution culminating in the uniquely flexible abilities of humans to use and make tools. Studies on the evolution of tool use are aimed at reconstructing the evolutionary history of this adaptation. Although this area of inquiry has historically been the interest of archeol...
The emergence of stone tools represents a significant milestone in hominin evolution culminating in the uniquely flexible abilities of humans to use and make tools. Studies on the evolution of tool use are aimed at reconstructing the evolutionary history of this adaptation. Although this area of inquiry has historically been the interest of archeol...
The present study examines cortical neuronal morphology in the African lion (Panthera leo leo), African leopard (Panthera pardus pardus), and cheetah (Acinonyx jubatus jubatus). Tissue samples were removed from prefrontal, primary motor, and primary visual cortices and investigated with a Golgi stain and computer-assisted morphometry to provide som...
The brainstem (midbrain, pons and medulla oblongata) and cerebellum (diencephalic prosomere 1 through to rhombomere 11) play central roles in the processing of sensorimotor information, autonomic activity, levels of awareness and the control of functions external to the conscious cognitive world of mammals. As such, comparative analyses of these st...
This video provides elementary school learners with an introduction to cetaceans and the concept of relative abundance. To learn more visit www.go2science.com a STEM learning initiative by Beth Heidemann and Curtis Bentley.
The tree pangolin is one of the eight extant species of Pholidota, with connicting phylogeny. Despite the expanded olfactory gene family, it is unknown if the structural and neurochemical architecture of the pangolin olfactory system support its behavioural preference for olfactory cues. We used a range of neuroanatomical stains (Nissl; Myeline; An...
All domesticated mammals exhibit marked reductions in overall brain size, however, it is unknown whether the corpus callosum, an integral white matter fiber pathway for interhemispheric cortical communication, is affected by domestication differentially or strictly in coordination with changes in brain size. To answer this question, we used quantit...
Relatively little neuroscience research has been focused on artiodactyls. Recent observations of complex social interactions in domestic and wild species suggests that analyses of artiodactyl brain anatomy would be of comparative value. In the current study, we examined how the distribution of cortical neuropil space (a proxy for connectivity) vari...
This study employed a range of neuroanatomical stains to determine the organization of the main and accessory olfactory systems within the brain of the tree pangolin. The tree pangolin has a typically mammalian olfactory system, but minor variations were observed. The main olfactory system is comprised of the layered main olfactory bulb (MOB), the...
We examined the effect of chronic prenatal alcohol exposure (PAE) on the process of adult neurogenesis in C57BL/6J mice at early adulthood (PND 56). Pregnant mice, and their in utero litters, were exposed to alcohol, through oral gavage, on gestational days 7–16, with recorded blood alcohol concentrations averaging 184 mg/dL (CA group). Two control...
Gigantopyramidal neurons, referred to as Betz cells in primates, were first identified in the primary motor cortex by Betz (1874) and are characterized by large somata and extensive basilar dendrites. Although there have been morphological descriptions and drawings of gigantopyramidal neurons in a limited number of species, quantitative investigati...
The hand metrics of Palaeolithic artists show a number of distinctive features that contrast with the low-variance hand metrics of modern Europeans, and with the majority of other modern humans. For example, the D2/D4 ratio in the Palaeolithic artists has a much greater spread of values and a greater degree of sexual dimorphism. We find that living...
We examined the effect of chronic prenatal alcohol exposure on the process of adult neurogenesis in C57BL/6J mice at early adulthood (PND 56). Pregnant mice, and their in utero litters, were exposed to alcohol, through oral gavage, on gestational days 7 – 16, with recorded blood alcohol concentrations averaging 184 mg/dL (CA group). Two control gro...
While cetaceans have captivated the imagination of the public, resulting in many anthropomorphic accounts of cetacean behavior, our current understanding of the cetacean brain is one that highlights the aberrant and divergent neural architecture of this group of mammals. This unusual structural arrangement of the cetacean brain stands in stark cont...
To the common observer, it would seem obvious that animals differ in their intelligence and that human intelligence, at least from our own biased perspective, is far superior to that of other animals. But what exactly is animal intelligence and how is it linked to the parameters of the brain? Knowledge on animal intelligence is not only of interest...
The present study describes the nuclear organization of the cholinergic, catecholaminergic, serotonergic and orexinergic systems in the brains of the springhare and Beecroft’s scaly-tailed squirrel following immunohistochemical labelling. We aimed to investigate any differences in the nuclear organization of these neural systems when compared to pr...
Definition: Evolutionary neuroscience is an interdisciplinary field of study which seeks to understand the evolution of the brain and nervous system and provides a framework for interpreting evolutionary changes in brain and brain component size or shape.
The field of evolutionary neuroscience has provided us with an enormous amount of comparative...
The current study provides the first systematic immunohistochemical neuroanatomical investigation of the systems involved in the control and regulation of sleep in an odontocete cetacean, the harbour porpoise (Phocoena phocoena). The odontocete cetaceans show an unusual form of mammalian sleep, with unihemispheric slow waves, suppressed REM sleep a...
This study provides the first systematic analysis of the nuclear organization of the neural systems related to sleep and wake in the basal forebrain, diencephalon, midbrain and pons of the river hippopotamus, one of the closest extant terrestrial relatives of the cetaceans. All nuclei involved in sleep regulation and control found in other mammals,...
The current study analyses the nuclear organization of the neural systems related to the control and regulation of sleep and wake in the basal forebrain, diencephalon, midbrain and pons of the minke whale, a mysticete cetacean. While odontocete cetaceans sleep in an unusual manner, with unihemispheric slow wave sleep (USWS) and suppressed REM sleep...
The species of the cetacean and artiodactyl suborders, which constitute the order Cetartiodactyla, exhibit very different sleep phenomenology, with artiodactyls showing typical bihemispheric slow wave and REM sleep, while cetaceans show unihemispheric slow wave sleep and appear to lack REM sleep. The aim of this study was to determine whether cetac...
The minicolumn has been defined as the smallest functional unit of the cortex with the widely-held view that there is a conservation of structure for this cortical processing unit. However, comparative data reveal significant differences among species in both the structure and composition of minicolumns. Here we review the available data on intersp...
The hippocampus is essential for the formation and retrieval of memories and is a crucial neural structure sub-serving complex cognition. Adult hippocampal neurogenesis, the birth, migration and integration of new neurons, is thought to contribute to hippocampal circuit plasticity to augment function. We evaluated hippocampal volume in relation to...
A previous study investigating potential adult hippocampal neurogenesis in microchiropteran bats failed to reveal a strong presence of this neural trait. As microchiropterans have a high field metabolic rate and a small body mass, it is possible that capture/handling stress may lead to a decrease in the detectable presence of adult hippocampal neur...
The structure of the hippopotamus brain is virtually unknown because few studies have examined more than its external morphology. In view of their semi-aquatic lifestyle and phylogenetic relatedness to cetaceans, the brain of hippopotamuses represents a unique opportunity for better understanding the selective pressures that have shaped the organiz...
It is a central assumption that larger bodies require larger brains, across species but also possibly within species with continuous growth throughout the lifetime, such as the crocodile. The current study investigates the relationships between body growth (length and mass) and the rates of growth of various subdivisions of the central nervous syst...
The current paper details our developing understanding of the evolution of large brains in mammals. In order to do this, we first define brains that we consider to be large – those that have passed the apparent 700-gram ceiling on brain mass evolution in the class Mammalia. The over-700-gram club includes certain species within the genus Homo, orde...
The current study provides a number of novel observations on the organization and structure of the cerebellar cortex of the African elephant by using a combination of basic neuroanatomical and immunohistochemical stains with Golgi and stereologic analysis. While the majority of our observations indicate that the cerebellar cortex of the African ele...
Increased connectivity of high-order association regions in the neocortex has been proposed as a defining feature of human brain evolution. At present, however, there are limited comparative data to examine this claim fully. We tested the hypothesis that the distribution of neuropil across areas of the neocortex of humans differs from that of one o...
The current chapter examines allometric exponents as they apply to the evolution of the size, or mass, of the modern human brain relative to the mass of the body. The mass of the brain is considered as a single level of organisation of the nervous system and is treated separately to other levels of organisation. A comprehensive dataset is used to e...
The current study used MR imaging to determine the volume of the cerebellum and its component parts in the brain of three adult male African elephants (Loxodonta africana) and compared this with published data from Asian elephants and other mammalian species including odontocete cetaceans, primates, chiropterans, insectivores, carnivores, and artio...
It is argued in this article that the human body both in health and disease cannot be fully understood without adequately accounting for the different levels of human variation. The article focuses on variation due to ancestry, arguing that the inclusion of information pertaining to ancestry in human anatomy teaching materials and courses should be...
In this paper we present a pilot survey focusing on the chiropractors' views on possible racial differences in their patients' response to treatment. A questionnaire was developed and validated through this study. Results of this -pilot survey -show that the majority of respondents did not see biological race as a significant factor in chiropractic...
This study used magnetic resonance imaging (MRI) to determine the volume of the ventricular system in the brain of three adult male African elephants (Loxodonta africana). The ventricular system of the elephant has a volume of ∼240 mL, an order of magnitude larger than that seen in the adult human. Despite this large size, allometric analysis indic...
The mammalian neocortex contains a great variety of neuronal types. In particular, recent studies have shown substantial morphological diversity among spiny projecting neurons in species that diverged close to the base of the mammalian radiation (e.g., monotremes, afrotherians, and xenarthrans). Here, we used a Golgi technique to examine different...
Human language is distinctive compared with the communication systems of other species. Yet, several questions concerning its emergence and evolution remain unresolved. As a means of evaluating the neuroanatomical changes relevant to language that accompanied divergence from the last common ancestor of chimpanzees, bonobos and humans, we defined th...
It is fitting that this book on Teaching Human Variation appear in 2009, for this year marks the bicentenary of the birth of Charles Darwin and the sesquicentenary of the publication of The Origin of Species by Means of Natural Selection. The concept of Natural Selection was put forward as a mechanism to explain how evolutionary change might have o...
Neural changes that occurred during human evolution to support language are poorly understood. As a basis of comparison to humans, we used design-based stereological methods to estimate volumes, total neuron numbers, and neuron densities in Brodmann's areas 44 and 45 in both cerebral hemispheres of 12 chimpanzees (Pan troglodytes), one of our speci...
Neocortical columns are functional and morphological units whose architecture may have been under selective evolutionary pressure in different mammalian lineages in response to encephalization and specializations of cognitive abilities. Inhibitory interneurons make a substantial contribution to the morphology and distribution of minicolumns within...
Inhibitory interneurons participate in local processing circuits, playing a central role in executive cognitive functions of the prefrontal cortex. Although humans differ from other primates in a number of cognitive domains, it is not currently known whether the interneuron system has changed in the course of primate evolution leading to our specie...
In this study, we assessed the distribution of cortical neurons immunoreactive for tyrosine hydroxylase (TH) in prefrontal cortical regions of humans and nonhuman primate species. Immunohistochemical methods were used to visualize TH-immunoreactive (TH-ir) neurons in areas 9 (dorsolateral prefrontal cortex) and 32 (anterior paracingulate cortex). T...
The derivation of discriminant function equations for skeletal elements of South African populations continues to be an area of interest to both forensic anthropologists and skeletal biologists alike. The skull of black South Africans has previously been subjected to discriminant function analysis, using four measurements and two indices; however,...
Estimating body mass/size/weight remains a crucial precursor to the evaluation of relative brain size and to achieving an understanding of brain evolution in fossil species. Despite the obvious close association between the metrics of postcranial elements and body mass a number of factors combine to reduce their utility. This study examines the fea...
The largely dominant adaptationist argument is currently used as the framework within which hominid brain evolution is explained; however these adaptationist explanations are inherently problematic and only suffice to ‘clutter’ our knowledge of the possible causes of hominid brain evolution. This study addresses the caveats observed in the fossil r...
