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PubMed1985

Mechanics of increased support of weight by the hindlimbs in primates.

Quadrupedal primates support most of their weight on their hindlimbs during locomotion. Neither the position of their center of gravity nor the average position of their foot contacts is substantially different from that of other quadrupeds supporting most of their weight on their forelimbs. Arguments are presented to support the theory that high levels of hindlimb retractor activity will produce this shift of support to the hindlimbs. If this muscular activity is appropriately timed, it will generate only low horizontal accelerations, which can be offset by small changes in the average position of the limbs. Estimates of muscular force are derived from force plate and kinematic data, which indicate that primates in fact do exhibit the postulated pattern of muscular activity. It is suggested that this shift occurs to reduce the compressive forces on the forelimbs.

Animals↗
PubMed1986

Ecological significance of hypometabolism in nonhuman primates: allometry, adaptation, and deviant diets.

The "Kleiber relationship" describes the interspecific allometry between body size and metabolism. Like other allometric relationships, the Kleiber relationship not only summarizes scaling effects across species but also provides a standard by which species can be compared. One well-noted deviation from the Kleiber relationship is "hypometabolism": metabolic rates below that expected for a given size. It has been suggested in the literature that hypometabolism may be a primitive mammalian trait, a thermoregulatory adaptation, an adaptation to arboreal folivory, or an adaptation to a diet that is deviant for body size. Data on primate physiology and behavior are used to evaluate these hypotheses. Only the deviant-diet hypothesis is supported by the data on nonhuman primates. Indeed, the Jarman-Bell relationship, which is the basis for this hypothesis, provides a more coherent explanation of correlated features of animal physiology and behavior than do the alternative models. Hypometabolism may be an energy-conserving adaptation to a variety of nutritional stresses. The present analysis underscores the point that metabolic rate, like foraging behavior, should be thought of as evolutionarily labile.

Adaptation, Physiological↗
PubMed1989

Gestation length, metabolic rate, and body and brain weights in primates: epigenetic effects.

The relationship of brain and body weights can be expressed in log-log regression: log (brain weight) = log (A) + B log (body weight). To investigate further the weights' similarity, gestation length and brain and body weights were determined from the literature for 46 primate genera. The results of allometric and path regression analyses suggest that the relationship between brain and body weights may not be mainly pleiotropic in the order Primates. The correlation between brain and body weights appears to be due to epigenetic factors in hyperplastic growth related to time constraint by gestation length and to energy utilization limitations imposed by metabolic rate.

Animals↗
PubMed1992

Brief communication: the popliteal sesamoid bone (cyamella) in primates.

A study of 246 adult nonhuman primates belonging to 34 genera indicates that a popliteal sesamoid bone is always present in the tendon of the popliteus muscle in Prosimii and Callitrichidae. The bone occurs only variably in Atelidae and Pongo, and is usually absent in Gorilla. The bone is absent, or very rare, in Cebus, Cercopithecidae, Hylobatidae, Pan, and humans. When the bone is present, it articulates with the posterior part of the articular surface of the lateral condyle of the tibia, and lies very close to the head of the fibula, at the angulated part of the popliteal tendon, near the tendomuscular junction. The presence of the popliteal sesamoid bone in primates is a primitive character.

Animals↗
PubMed1992

Erosive arthritis and spondyloarthropathy in Old World primates.

Presence of spine and sacroiliac involvement and the nature and distribution of the erosive lesions allow definitive diagnosis of spondyloarthropathy. Thus, spondyloarthropathy was identified in Theropithecus, Papio, Cercopithecus, Macaca, Colobus, Presbytis, and Hylobates. Only monarticular erosive disease was present in prosimians, precluding a diagnosis of spondyloarthropathy for that group. The distribution of erosive disease and axial joint involvement in 1,349 non-prosimian Old World primates is quite characteristic of that noted in human psoriatic arthritis. While Reiter's syndrome must also be considered, the histologic appearance of skin lesions in Macaca is characteristic of psoriasis. Evidence of spondyloarthropathy abounds in the literature of primate skeletal disease. Environmentally based contagions may be important in the pathophysiology of spondyloarthropathy. The wide geographic distribution of the phenomena in monkeys suggests a "panendemic," with limited individual susceptibility (compared to that noted in gorillas and chimpanzees). Identical occurrence of erosive arthritis/spondyloarthropathy in free-ranging and artificially restrained animals suggests that spondyloarthropathy can validly be studied in artificially restrained populations. This perspective should allow application of human therapeutic approaches to and perhaps improve the quality of life for artificially restrained, afflicted individuals.

Animals↗
PubMed1994

New early eocene anaptomorphine primate (Omomyidae) from the Washakie Basin, Wyoming, with comments on the phylogeny and paleobiology of anaptomorphines.

Recent paleontological collecting in the Washakie Basin, southcentral Wyoming, has resulted in the recovery of over 100 specimens of omomyid primates from the lower Eocene Wasatch Formation. Much of what is known about anaptomorphine omomyids is based upon work in the Bighorn and Wind River Basins of Wyoming. This new sample documents greater taxonomic diversity of omomyids during the early Eocene and contributes to our understanding of the phylogeny and adaptations of some of these earliest North American primates. A new middle Wasatchian (Lysitean) anaptomorphine, Anemorhysis savagei, n. sp., is structurally intermediate between Teilhardina americana and other species of Anemorhysis and may be a sister group of other Anemorhysis and Trogolemur. Body size estimates for Anemorhysis, Tetonoides, Trogolemur, and Teilhardina americana indicate that these animals were extremely small, probably less than 50 grams. Analysis of relative shearing potential of lower molars of these taxa indicates that some were primarily insectivorous, some primarily frugivorous, and some may have been more mixed feeders. Anaptomorphines did not develop the extremes of molar specialization for frugivory or insectivory seen in extant prosimians. Incisor enlargement does not appear to be associated with specialization in either fruits or insects but may have been an adaptation for specialized grooming or food manipulation.

Adaptation, Physiological↗
PubMed1994

Incisor microwear of Sumatran anthropoid primates.

Several studies have suggested that incisor microwear reflects diet and feeding adaptations of anthropoids. However, such studies have been largely qualitative, and interpretations have relied on anecdotal references to diet and tooth use reported in the socioecology literature. The current study relates incisor microwear in four anthropoid primates to specific ingestive behaviors and food types. Central incisor casts of wild-shot museum specimens of Hylobates lar, Macaca fascicularis, Pongo pygmaeus, and Presbytis thomasi were examined by scanning electron microscopy, and analyzed using a semiautomated image analysis procedure. Microwear patterns were used to generate predictions regarding diet and anterior tooth use. These predictions were evaluated using data collected during a 1 year study of feeding behavior of these same taxa in the wild (Ungar, 1992, 1994a,b). Results suggest that (1) enamel prism relief is associated with the effectiveness of etching reagents in foods, (2) dental calculus buildup results from a lack of incisor use and perhaps the ingestion of sugar-rich foods, (3) striation density varies with degree of anterior tooth use in the ingestion of abrasive food items, (4) striation breadth is proposed to relate to the ratio of exogenous grit to phytoliths consumed; and (5) preferred striation orientation indicates the direction that food items are pulled across the incisors during ingestion. It is concluded that incisor microwear studies can contribute to the understanding of diets and feeding behaviors of extinct primates.

Analysis of Variance↗
PubMed2006

Hindlimb adaptations in Ourayia and Chipetaia, relatively large-bodied omomyine primates from the Middle Eocene of Utah.

North American omomyids represent a tremendous Eocene radiation of primates exhibiting a wide range of body sizes and dietary patterns. Despite this adaptive diversity, relatively little is known of the postcranial specializations of the group. Here we describe hindlimb and foot bones of Ourayia uintensis and Chipetaia lamporea that were recovered from the Uinta B member (early Uintan Land Mammal Age), Uinta Formation, Utah. These specimens provide insights into the evolution of postcranial adaptations across different body sizes and dietary guilds within the Eocene primate radiation. Body mass estimates based on talar measurements indicate that Ourayia uintensis and Chipetaia lamporea weighed about 1,500-2,000 g and 500-700 g, respectively. Skeletal elements recovered for Ourayia include the talus, navicular, entocuneiform, first metatarsal, and proximal tibia; bones of Chipetaia include the talus, navicular, entocuneiform, and proximal femur. Both genera had opposable grasping big toes, as indicated by the saddle-shaped joint between the entocuneiform and first metatarsal. Both taxa were arboreal leapers, as indicated by a consistent assemblage of characters in all represented bones, most notably the somewhat elongated naviculars, the high and distinct trochlear crests of the talus, the posteriorly oriented tibial plateau (Ourayia), and the cylindrical head of the femur (Chipetaia). The closest resemblances to Ourayia and Chipetaia are found among the Bridger omomyines, Omomys and Hemiacodon. The results of our comparisons suggest that the later, larger, more herbivorous omomyines from Utah retained a skeletal structure characteristic of earlier, smaller North American omomyids.

Adaptation, Physiological↗
PubMed2004

Distribution of olfactory epithelium in the primate nasal cavity: are microsmia and macrosmia valid morphological concepts?

The terms "microsmatic" and "macrosmatic" are used to compare species with greater versus lesser olfactory capabilities, such as carnivores compared to certain primates. These categories have been morphologically defined based on the size of olfactory bulb and surface area of olfactory epithelium in the nasal fossa. The present study examines assumptions regarding the morphological relationship of bony elements to the olfactory mucosa, the utility of olfactory epithelial surface area as a comparative measurement, and the utility of the microsmatic concept. We examined the distribution of olfactory neuroepithelium (OE) across the anteroposterior length of the nasal fossa (from the first completely enclosed cross-section of the nasal fossa to the choanae) in the microsmatic marmoset (Callithrix jacchus) compared to four species of nocturnal strepsirrhines (Otolemur crassicaudatus, O. garnetti, Microcebus murinus, and Cheirogaleus medius). Adults of all species were examined and infant C. jacchus, O. crassicaudatus, M. murinus, and C. medius were also examined. All specimens were serially sectioned in the coronal plane and prepared for light microscopic study. Distribution of OE across all the turbinals, nasal septal surfaces, and accessory spaces of the nasal chamber was recorded for each specimen. The right nasal fossae of one adult C. jacchus and one neonatal M. murinus were also three-dimensionally reconstructed using Scion Image software to reveal OE distribution. Findings showed OE to be distributed relatively more anteriorly in adult C. jacchus compared to strepsirrhines. It was also distributed more anteriorly along the nasal septal walls and recesses in neonates than adults. Our findings also showed that OE surface area was not a reliable proxy for receptor neuron numbers due to differing OE thickness among species. Such results indicate that nasal cavity morphology must be carefully reconsidered regarding traditional functional roles (olfaction versus air conditioning) assigned to various nasal cavity structures. At present, the microsmatic concept itself lacks a basis in nasal chamber morphology, since OE may have varying patterns of distribution among different primates.

Adaptation, Physiological↗
PubMed2004

Comparative analysis of the role of olfaction and the neocortex in primate intrasexual competition.

In strepsirrhine primates, the accessory olfactory system plays an important role in intrasexual competition. However, it does not play the same role in most haplorhines. In these primates, the main olfactory system and neocortex may have evolved to serve similar functions as the accessory olfactory system in strepsirrhines. To test these hypotheses, the relative size of the main olfactory bulb and neocortex were analyzed for associations with male and female competition frequency and intensity (categorized as low or high). Because neocortex size and competition intensity are associated with diet, only frugivorous species were analyzed (catarrhines, n = 7; platyrrhines, n = 8). Neither the size of the main olfactory bulb nor the neocortex was significantly associated with intrasexual competition among males. However, neocortex size was related to the frequency of female competition. Because the main olfactory system and neocortex both serve multiple purposes, there may not be a single behavioral variable that has selected for their size. Furthermore, categorization of male and female competition intensity reflects physically aggressive behavior. Use of the neocortex for social manipulation may allow males to obtain copulations and females to obtain food resources despite poor physical fighting abilities and low dominance rank.

Animals↗
PubMed2004

Expression of neuron-specific markers by the vomeronasal neuroepithelium in six species of primates.

Vomeronasal organ (VNO) morphology varies markedly across primate taxa. Old World monkeys display no postnatal VNO. Humans and at least some apes retain a vestigial VNO during postnatal life, whereas the strepsirrhines and New World Monkeys present a morphologically well-defined VNO that, in many species, is presumed to function as an olfactory organ. Available microanatomical and behavioral studies suggest that VNO function in these species does not precisely duplicate that described in other mammalian taxa. The questions of which species retain a functional VNO and what functions they serve require inquiry along diverse lines but, to be functional, the vomeronasal epithelium must be neuronal and olfactory. We used immunohistochemistry to establish these criteria in six primate species. We compared the expression of two neuronal markers, neuron-specific beta-tubulin (BT) and protein gene product 9.5, and olfactory marker protein (OMP), a marker of mature olfactory sensory neurons, in paraffin-embedded VNO sections from two strepsirrhine and four haplorhine species, all of which retain morphologically well-defined VNOs during postnatal life. The infant Eulemur mongoz, adult Otolemur crassicaudatus, neonatal Leontopithicus rosalia, and adult Callithrix jacchus express all three proteins in their well-defined vomeronasal neuroepithelia. The infant Tarsius syrichta showed some BT and OMP immunoreactivity. We establish that two strepsirrhine species and at least some New World haplorhines have mature sensory neurons in the VNO. In contrast, at all ages examined, Saguinus geoffroyi VNO expresses these markers in only a few cells.

Aging↗
PubMed2005

Functional shape of the skull in vertebrates: which forces determine skull morphology in lower primates and ancestral synapsids?

In order to determine the extent to which the shape of the synapsid skull is adapted for resisting the mechanical loads to which it is subjected, block- or simple plate-shaped finite-element models were constructed and loaded with external muscle and bite forces in locations estimated to resemble points of application of these forces. These 2D or 3D finite-element models were iteratively loaded and modified by removing elements that experience only low stresses, and the resulting morphologies of the models were compared with fossil skulls of synapsids and the skulls of extant mammals. The results suggest that the stress flows in these unspecific models are very similar to the arrangement of bone material in real skulls. Morphological differences between taxa depend on a few a priori conditions: length and position of the tooth rows in relation to the braincase, arrangement of muscles, position of the orbits, and position of the nasal opening. Given these initial conditions, finite-element analysis consistently reveals the close similarity between stress flows and real skulls. The major difference between mammal-like reptiles and primates is the size of the braincase. This difference accounts for most of the morphological divergence. The postorbital bar seems to be a constructional element of the skull, rather than a means to protect the eyes. The skull shapes of higher primates are determined mainly by masticatory forces and less by external forces acting on the head. This study demonstrates the utility of finite-element modeling for testing hypotheses regarding relationships between form and function in vertebrate skulls.

Animals↗
PubMed2006

Specializations of the granular prefrontal cortex of primates: implications for cognitive processing.

The biological underpinnings of human intelligence remain enigmatic. There remains the greatest confusion and controversy regarding mechanisms that enable humans to conceptualize, plan, and prioritize, and why they are set apart from other animals in their cognitive abilities. Here we demonstrate that the basic neuronal building block of the cerebral cortex, the pyramidal cell, is characterized by marked differences in structure among primate species. Moreover, comparison of the complexity of neuron structure with the size of the cortical area/region in which the cells are located revealed that trends in the granular prefrontal cortex (gPFC) were dramatically different to those in visual cortex. More specifically, pyramidal cells in the gPFC of humans had a disproportionately high number of spines. As neuron structure determines both its biophysical properties and connectivity, differences in the complexity in dendritic structure observed here endow neurons with different computational abilities. Furthermore, cortical circuits composed of neurons with distinguishable morphologies will likely be characterized by different functional capabilities. We propose that 1. circuitry in V1, V2, and gPFC within any given species differs in its functional capabilities and 2. there are dramatic differences in the functional capabilities of gPFC circuitry in different species, which are central to the different cognitive styles of primates. In particular, the highly branched, spinous neurons in the human gPFC may be a key component of human intelligence.

Animals↗
PubMed2005

From the margins of the genome: mobile elements shape primate evolution.

As is the case with mammals in general, primate genomes are inundated with repetitive sequence. Although much of this repetitive content consists of "molecular fossils" inherited from early mammalian ancestors, a significant portion of this material comprises active mobile element lineages. Despite indications that these elements played a major role in shaping the architecture of the genome, there remain many unanswered questions surrounding the nature of the host-element relationship. Here we review advances in our understanding of the host-mobile element dynamic and its overall impact on primate evolution.

Alternative Splicing↗
PubMed1985

Differences among primates in defence against infection: sensitivity of polymorphonuclear leukocytes to fMet-Leu-Phe.

The sensitivity of polymorphonuclear leukocytes (PMN) to N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) for chemotaxis and for lysosomal enzyme release was examined using the PMN of four primate species, human (H. sapiens), chimpanzee (P. troglodytes), rhesus monkey (M. mulatta), and cotton-headed tamarin (S. (O) oedipus). The 50 per cent effective concentrations (EC50) of fMet-Leu-Phe for chemotaxis were 2.5 X 10(-9) M in human, 10(-9) M in chimpanzee, 8 X 10(-8) M in rhesus monkey, and 3.3 X 10(-6) M in tamarin. The EC50 values of fMet-Leu-Phe for myeloperoxidase (MPO) release were 10(-8) M in human, 4 X 10(-8) M in chimpanzee, 4 X 10(-8) M in rhesus monkey, and 10(-6) M in tamarin and those for beta-glucuronidase release were 4 X 10(-9) M, 6.4 X 10(-8) M, 1.8 X 10(-7) M, and 1.6 X 10(-6) M, respectively. Thus, the sensitivity to fMet-Leu-Phe for chemotaxis was in the order: chimpanzee congruent to human greater than rhesus monkey greater than tamarin, and that for the release of lysosomal enzymes, MPO and beta-glucuronidase, was in the order: human greater than chimpanzee greater than rhesus monkey greater than tamarin. These results appear to indicate that the sensitivity to fMet-Leu-Phe increases in the order of evolution of primates toward the human, and suggest that the sensitivity of PMN in the defence function against infection also increases in the same order.

Animals↗
PubMed1975

Cerebellar corticovestibular fibers of the posterior lobe in a prosimian primate, the lesser bushbaby (Galago senegalensis).

The orginization of cerebellar corticovestibular fibers was studied in a prosimian primate (Galago senegalensis) using the Fink and Heimer ('67) method. The vestibular complex of Galago is larger than in other mammals and some higher primates. Vermis lobule IX contributes the largest number of fibers to the ipsilateral vestibular complex. Lobules VI and VIII give rise to lesser, but similar, numbers of fibers which also pass into the ipsilateral vestibular nuclei. Vermis lobule VII and the paravermal and lateral cortices contribute extremely sparse numbers of fibers to the dorsal area of the ipsilateral vestibular complex. All degenerated fibers enter the vestibular nuclei through a large diffusely organized juxtarestiform body. Fibers from vermis lobule VII and the paravermal and lateral cortices terminate in dorsal areas of the ipsilateral vestibular nuclei. Vermis lobule VI projects into dorsal and lateral regions of the ipsilateral SVN, LVN and SpVN. Vermis lobules VIII and IX project into the dorsal and into progressively more central and medial regions of the ipsilateral SVN, LVN, and SpVN. This gives the clear impression of a rostro-caudal origin of fibers from the posterior lobe vermis which terminate in an overlapping lateral to medial sequence in the vestibular complex. In addition to its projection into the vestibular nuclei, lesions of vermis lobule IX also elicit degeneration in dorsal areas of the ipsilateral medullary reticular formation and in the ipsilateral parabrachial nuclei.

Animals↗
PubMed1986

The accessory optic system in a prosimian primate (Microcebus murinus): evidence for a direct retinal projection to the medial terminal nucleus.

The accessory optic system (AOS) was studied in the prosimian primate, Microcebus murinus, by using intraocular injections of the anterograde tracers 3H-proline and horseradish peroxidase (HRP). Retinal fibers were found to terminate bilaterally in all three mesencephalic AOS nuclei as defined by Hayhow ('66, J. Comp. Neurol. 126:653-672). In contrast to previous reports in primates, we find that both the ventral and dorsal divisions of the medial terminal nucleus (MTN) receive projections from the retina. The ventral MTN is composed of a compact triangular group of cells, situated at the medial base of the cerebral peduncle, rostral to the rootlets of the third cranial nerve. The dorsal MTN extends dorsomedial to the substantia nigra and is composed of characteristic fusiform cells embedded in a fibrous neuropil. Although the cells of the dorsal MTN intermingle somewhat with the nigral cells, the nucleus is clearly distinguished by cyto- and myeloarchitectural features. The large lateral terminal nucleus (LTN) receives a dense projection from the retina and forms a prominent bulge on the lateral surface of the cerebral peduncle. The dorsal terminal nucleus (DTN) is located between the brachia of the superior and inferior colliculi, near the origin of the superior fasciculus of the accessory optic tract (AOT). This fasciculus is composed of anterior, middle, and posterior branches. In addition, a ventral group of fibers, corresponding to the inferior fasciculus of the AOT previously described in nonprimates, was identified in all planes of section. The results confirm the existence of a common plan of AOS organization in mammals.

Adaptation, Biological↗
PubMed1989

Starburst amacrine cells of the primate retina.

A group of readily recognized amacrine cells were observed in Golgi-impregnated and flat-mounted macaque, baboon, and human retinas. These cells had roughly-circular or oval dendritic fields that were narrowly stratified within the inner plexiform layer (IPL). Most of these cells stratified in the inner half (sublamina b) of the IPL, and they had their somata in the ganglion-cell layer; a few stratified in the outer half (sublamina a) of the IPL and had their somata in the amacrine-cell layer. Typically, a single dendrite issued from the soma, and, after passing for 10 microns or so, gave rise to five or more radiate processes. As these processes neared the edge of the dendritic field they branched, turned, and became varicose. Most showed no evidence of an axon, although a few had a short process extending inward, toward the optic-fiber layer. Dendritic-field diameters were about 100 microns near the fovea and increased to about 350 microns in the peripheral retina. Mean somal diameter also increased slightly from near the fovea (7.8 microns) to the periphery (8.7 microns). Although the primate cells are smaller, and there are some minor differences in the form of the dendritic fields, these cells appear to be morphologically equivalent to the starburst amacrines of the rabbit retina, whose counterparts have also been observed in the retinas of rats and cats. Presuming that these cells correspond to the choline acetyltransferase immunoreactive primate cells described by Mariani and Hersh (J. Comp. Neurol. 267:269-280, '87), their overlap factor is about ten for the type whose somata lay in the ganglion-cell layer and about 0.25 for those whose somata lay in the amacrine-cell layer.

Animals↗