Neocortex Size Predicts Group Size in Carnivores and Some Insectivores

Neocortex size has been shown to correlate with group size in primates. Data for carnivores and insectivores are used to test the generality of this relationship. The data suggest that carnivores lie on the same grade as the primates, but that insectivores lie on a separate grade to the left of these two orders. Among the insectivores, there appears to be a distinction between the ‘advanced’ genera (which show a relationship between group size and neocortex size) and the ‘basal’ genera (which do not).     

Comparative aspects of a study of the self-regulation of higher nervous activity in experimental neuroses in dogs, cats and rats

The higher nervous activity has been studied by means of motor-alimentary conditioned reflexes and delayed reactions in dogs, cats and albino rats at early stages of development of experimental informational neurosis. It was shown that formation of stable pathological reactions is preceeded by self- regulational activity of the brain directed towards elimination of a pathological situation, as well as to the increase of the stability of the nervous system to pathogenic agents. Comparative studies on rodents and predatory animals indicate that in different species the same pathogenic effects on the brain may elicit different forms of self-regulation of the higher nervous activity.     

The insertions of the cruropedal muscles and implications for the locomotor evolution in primates

We examined gross-anatomically the cruropedal muscles, which control the toe movements, in some species of insectivores, rodents and primates including humans, with a focus on the phylogenetic developments of these muscles including the distribution patterns of the tendons to the toes. Morphological changes corresponding to the phylogenetic advancement from primitive terrestrial mammals to arboreal primates were found in the short extensors and flexors, presumably in association with the enhancement of independent digital mobility. In contrast, the changes which correspond to the acquisition of terrestrial bipedality in humans were identified in the development of extensors and flexors which govern the first toe, as well as in establishment of the peroneus tertius that dorsi-flexes the talocrural joint.     

Inference of mutation parameters and selective constraint in mammalian coding sequences by approximate Bayesian computation

We develop an inference method that uses approximate Bayesian computation (ABC) to simultaneously estimate mutational parameters and selective constraint on the basis of nucleotide divergence for protein-coding genes between pairs of species. Our simulations explicitly model CpG hypermutability and transition vs. transversion mutational biases along with negative and positive selection operating on synonymous and nonsynonymous sites. We evaluate the method by simulations in which true mean parameter values are known and show that it produces reasonably unbiased parameter estimates as long as sequences are not too short and sequence divergence is not too low. We show that the use of quadratic regression within ABC offers an improvement over linear regression, but that weighted regression has little impact on the efficiency of the procedure. We apply the method to estimate mutational and selective constraint parameters in data sets of protein-coding genes extracted from the genome sequences of primates, murids, and carnivores. Estimates of CpG hypermutability are substantially higher in primates than murids and carnivores. Nonsynonymous site selective constraint is substantially higher in murids and carnivores than primates, and autosomal nonsynonymous constraint is higher than X-chromsome constraint in all taxa. We detect significant selective constraint at synonymous sites in primates, carnivores, and murid rodents. Synonymous site selective constraint is weakest in murids, a surprising result, considering that murid effective population sizes are likely to be considerably higher than the other two taxa.     

Molecular distance and divergence time in carnivores and primates

Numerous studies have used indices of genetic distance between species to reconstruct evolutionary relationships and to estimate divergence time. However, the empirical relationship between molecular-based indices of genetic divergence and divergence time based on the fossil record is poorly known. To date, the results of empirical studies conflict and are difficult to compare because they differ widely in their choice of taxa, genetic techniques, or methods for calibrating rates of molecular evolution. We use a single methodology to analyze the relationship of molecular distance and divergence time in 86 taxa (72 carnivores and 14 primates). These taxa have divergence times of 0.01-55 Myr and provide a graded series of phylogenetic divergences such that the shape of the curve relating genetic distance and divergence time is often well defined. The techniques used to obtain genetic distance estimates include one- and two-dimensional protein electrophoresis, DNA hybridization, and microcomplement fixation. Our results suggest that estimates of molecular distance and divergence time are highly correlated. However, rates of molecular evolution are not constant; rather, in general they decline with increasing divergence time in a linear fashion. The rate of decline may differ according to technique and taxa. Moreover, in some cases the variability in evolutionary rates changes with increasing divergence time such that the accuracy of nodes in a phylogenetic tree varies predictably with time.     

Individual typological features reflected in different stages of learning and related changes in dopamine transport in the mesolimbic brain

A hypothesis is proposed according to which there is a strong similarity between the individual typological features of animals (humans) and different stages of learning processes. The hypothesis is supported by the results of comparisons of psychophysiological and neurochemical indices of different stages of conditioning and various typologies of higher nervous activity. Such comparisons reveal a high similarity between the generalization phase and impulsivity, the phase a learned conditioned reflex and self-controlled behaviour, and overlearned CR and a state of "psychosis". Functional states close to pathology and possibilities of development and manifestation of several psychotic states depending on psychophysiological and neurochemical organization of learning processes are also considered.     

A cross-species analysis of carnivore,primate, and hominid behaviour

The traditional assumption that the origin of human behavior is found within the higher primates rather than the social carnivores is based on failure to adequately define primate and carnivore behavior. Phyletic classification takes no account of convergence and divergence; the behavior of a species is not necessarily characteristic of its order. Of 8 behavior variables that distinguish the order primates from the order carnivora, preagricultural man resembles the carnivores on 7 items: food sharing, food storing, cannibalism, surplus killing, interspecies intolerance, feeding of young, and division of labor; resembling the order primates only in group defense. The original form of much human behavior is found within the carnivores.     

Conditioned reflex activity and several vegetative reactions in dogs during the recovery period following repeated reanimation]

Conditioned activity and vegetative reactions were studied in dogs which repeatedly underwent clinical death from electrical trauma and were reanimated by donor artificial blood circulation. (The first clinical death was provoked 15 to 18 months prior to the repeated death and was caused by drowning and blood loss). On the first few days after reanimation the functions of the higher parts of the CNS and the vegetative nervous system were considerably disturbed. This was manifested in diminished effector reactions to conditioned stimuli, in narcotic and ultraparadoxal phases in conditioned activity, in tachycardia and a higher respiratory rate. The disturbances gradually diminished and by the 5th to 13th day following reanimation completely disappeared. The nature and depth of the disturbances correlated with the basic properties of the animals' type of higher nervous activity. The conditioned reactions were restored despite the retained pronounced dystrophic and destructive changes in the cerebral cortex. This is significant proof of important compensatory capacity for conditioned activity in dogs.     

Peculiarities of modifying influence of the factors forming the functional status of the central nervous system on dynamics of the rat higher nervous activity disturbances totally exposed to electron and gamma-radiation at a dose of 100 Gy

The dynamics of using a stabilized motor defensive conditioned reflex of active avoidance in "shuttle-box" in rats after the total influence of high energy electrons and gamma-rays at a dose of 100 Gy and a modifying influence of the two most important factors forming the functional status of the central nervous system: the stage of the conditioned reflex consolidation and typological peculiarities of the higher nervous activity have been investigated. The influence of both types of ionizing radiation has been shown to cause far more profound disturbances of non consolidated conditioned reflexes in comparison with the automatized conditioned reflexes and provoke an inverted picture of disturbances in the animals with opposed peculiarities of the higher nervous activity. The qualitative picture of the dynamics of disturbances that are caused by these types of radiation is identical. In summary, the studied conditions that form the functional status of the central nervous system determine the nature of neuroradiation syndrome to a greater extent than differences in the effectiveness of these types of radiation.     

Molar microwear in extant small-bodied faunivorous mammals: An analysis of feature density and pit frequency

This study quantitatively examined molar microwear in nine species of extant small-bodied faunivorous primates and microchiropterans. Comparative analyses were performed within the food category faunivory, both between hard- and soft-object feeding faunivores and between primarily insectivorous and carnivorous taxa. Additionally, microwear in faunivores was compared to that reported in the literature for frugivorous and folivorous primates. The results indicated that although insectivores and carnivores could not be distinguished by microwear analyses, hard-object faunivores (i. e., those that primarily consume beetles or actively comminute bone) can be readily distinguished from soft-object faunivores (i. e., moth, caterpillar, or vertebrate flesh specialists). The hard-object faunivores consistently exhibited greater pit frequencies (in excess of 40%). Furthermore, comparisons of these microwear data on faunivorous mammals to previous work on frugivorous and folivorous primates (Teaford, 1988, pers. comm.; Teaford and Runestad, 1992, pers. comm.; Teaford and Walker: American Journal of Physical Anthropology 64:191–200, 1984) permitted three observations to be made. 1) Faunivores tend to have higher mean feature densities than either frugivores or folivores, although these differences are not consistently statistically distinct. 2) Faunifores and frugivores that feed on hard-objects have comparable mean pit frequencies. 3) Although it is impossible to distinguish faunivores and folivores on the basis of metric analysis of gross molar morphology, this distinction can be made on microwear criteria. Both hard- and soft-object faunivores exhibit much higher mean pit frequencies than primarily folivorous species. © 1993 Wiley-Liss, Inc.     

An annotated checklist of mammals of Kenya

Kenya has a rich mammalian fauna. We reviewed recently published books and papers including the six volumes of Mammals of Africa to develop an up-to-date annotated checklist of all mammals recorded from Kenya. A total of 390 species have been identified in the country, including 106 species of rodents,104 species of bats, 63 species of even-toed ungulates(including whales and dolphins), 36 species of insectivores and carnivores, 19 species of primates,five species of elephant shrews, four species of hyraxes and odd-toed ungulates, three species of afrosoricids, pangolins, and hares, and one species of aardvark, elephant, sirenian and hedgehog. The number of species in this checklist is expected to increase with additional surveys and as the taxonomic status of small mammals(e.g., bats, shrews and rodents) becomes better understood.     

Patterns in the transition from normal to neurosis in dogs with different typological traits in food and defensive situations

At comparison of the formation of neurosis in dogs with different typological characteristics in conditions with alimentary and pain reinforcement, a resemblance was revealed of transition from norm to the initial stage of pathology. In strong animals a development was seen of compensatory tachycardia at circular changes of conditioned activity. Weak type dogs are characterized by a lowering or full disappearance of reflexes in combination with bradycardia. The method of differentiation, allowing in situations with alimentary reinforcement to classify the tested animals according to the type of higher nervous activity and differentiate the states of "norm" and "initial stage of neurosis", proved to be effective for the analogous aims also in studies with defensive reinforcement.     

Patterns in the ontogenetic development of certain forms of higher nervous activity in rhesus macaques

Studies have been made on ontogenetic development of simple and complex behavioural forms, realization of certain sequence of motor feeding conditioned reflexes, visual differentiation of signals, short-term memory and probability prediction in rhesus monkeys. Evolutionary features of ontogenetic development of some of the forms of the higher nervous activity were revealed. Both similarities and differences were noted in animals from three age groups. In ontogenesis of lower monkeys, the development of the main nervous processes of the higher nervous activity (learning, memory, etc.) takes place gradually depending on the age of a baby and the level of integrative activity of the brain.     

Molecular evolution inferred from immunological cross-reactivity of immunoglobulin G among Chiroptera and closely related species.

We examined the relationships between Megachiroptera and Microchiroptera, and between Chiroptera and other closely related species by the cross-reactivity of immunoglobulin epitopes. Rabbit polyclonal antibody to bat IgG was used for determining the cross-reactivity by a competitive ELISA method. Megachiroptera and Microchiroptera showed high cross-reactivity, over 95.3%, with each other. However, primates and insectivores showed very low cross-reactivity, 8.6 to 20.2% and 5.3 to 12.7%, respectively. These results suggest that suborders of Chiroptera are monophyletic and Chiroptera have a relatively closer relationship to primates than to insectivores.     

Features of the formation and dynamics of short-term image memory in the rat

Direct and indirect methods of delayed reactions showed that short-term image memory of rats elaborated on the basis of conditioned signals in poorly developed and its duration is not more than 1 s. While testing this memory, changes in the behaviour were seen, pointing to the development of "hard state" in the higher nervous activity of animals. Short-term image memory based on complex perception was shown to be well developed in rats, and by many characteristics it approximated to the memory of highly organized animals. The ability to reproduce the short-term image memory on the basis of conditioned signals is supposed to be a complex form of psychonervous activity of animals, and in rodents it appears to be at an initial stage of development.     

Volume comparisons in the cerebellar complex of primates. I. Ventral pons

Volumes of the ventral pons (VPo) were measured in 82 brains of primates, Scandentia, and Insectivora, and the relative size of the VPo was expressed by size indices. The reference line was through the prosimian average; the mean index of prosimians was set at 1. The taxonomic groups arranged in a sequence of ascending mean VPo indices were: Insectivora (0.04), prosimians (1.00), monkeys (2.55), apes (4.48) and man (9.44). Thus, the VPo of man is more than 9 times larger than that of isoponderous average prosimians, and more than 230 times larger than that of isoponderous "basal' insectivores. The indices may reflect trends and extent of VPo evolution in primate phylogeny.     

Relief index of second mandibular molars is a correlate of diet among prosimian primates and other euarchontan mammals

This study describes and tests a new method of calculating a shape metric known as the relief index (RFI) on lower second molars of extant euarchontan mammals, including scandentians (treeshrews), dermopterans (flying lemurs), and prosimian primates (strepsirhines and tarsiers). RFI is the ratio of the tooth crown three-dimensional area to two-dimensional planar area. It essentially expresses hypsodonty and complexity of tooth shape. Like other measurements of complexity, RFI ignores taxon-specific features, such as certain cusps and crests, which are usually considered in more traditional studies of tooth function. Traditional statistical analyses of the study sample show that RFI distinguishes taxa with differing amounts of structural carbohydrates in their diets, with frugivore/gramnivores being significantly lower in RFI than omnivores, and insectivores/folivores being significantly higher in RFI than the other two. Information on absolute size, or body mass, is needed to reliably parse out insectivores and folivores; however, if the study sample is limited to Primates, RFI alone distinguishes many folivores (lower) from insectivores (higher). Finally, phylogenetically independent contrasts of RFI and dietary preference are strongly correlated with one another, indicating that variance in RFI is better explained by dietary diversity than phylogenetic affinity in this sample. Because of the accuracy and phylogenetic insensitivity of the RFI among Euarchonta, this method can be applied to fossil primates and stem-primates (plesiadapiforms) and used to elucidate and compare their dietary preferences. Such comparisons are important for developing a more detailed view of primate evolution.     

Canine size, shape, and bending strength in primates and carnivores

Anthropoid primates are well known for their highly sexually dimorphic canine teeth, with males possessing canines that are up to 400% taller than those of females. Primate canine dimorphism has been extensively documented, with a consensus that large male primate canines serve as weapons for intrasexual competition, and some evidence that large female canines in some species may likewise function as weapons. However, apart from speculation that very tall male canines may be relatively weak and that seed predators have strong canines, the functional significance of primate canine shape has not been explored. Because carnivore canine shape and size are associated with killing style, this group provides a useful comparative baseline for primates. We evaluate primate maxillary canine tooth size, shape and relative bending strength against body size, skull size, and behavioral and demographic measures of male competition and sexual selection, and compare them to those of carnivores. We demonstrate that, relative to skull length and body mass, primate male canines are on average as large as or larger than those of similar sized carnivores. The range of primate female canine sizes embraces that of carnivores. Male and female primate canines are generally as strong as or stronger than those of carnivores. Although we find that seed-eating primates have relatively strong canines, we find no clear relationship between male primate canine strength and demographic or behavioral estimates of male competition or sexual selection, in spite of a strong relationship between these measures and canine crown height. This suggests either that most primate canines are selected to be very strong regardless of variation in behavior, or that primate canine shape is inherently strong enough to accommodate changes in crown height without compromising canine function.     

Comparative aspects of trophoblast development and placentation

Based on the number of tissues separating maternal from fetal blood, placentas are classified as epitheliochorial, endotheliochorial or hemochorial. We review the occurrence of these placental types in the various orders of eutherian mammals within the framework of the four superorders identified by the techniques of molecular phylogenetics. The superorder Afrotheria diversified in ancient Africa and its living representatives include elephants, sea cows, hyraxes, aardvark, elephant shrews and tenrecs. Xenarthra, comprising armadillos, anteaters and sloths, diversified in South America. All placentas examined from members of these two oldest superorders are either endotheliochorial or hemochorial. The superorder Euarchontoglires includes two sister groups, Glires and Euarchonta. The former comprises rodents and lagomorphs, which typically have hemochorial placentas. The most primitive members of Euarchonta, the tree shrews, have endotheliochorial placentation. Flying lemurs and all higher primates have hemochorial placentas. However, the lemurs and lorises are exceptional among primates in having epitheliochorial placentation. Laurasiatheria, the last superorder to arise, includes several orders with epitheliochorial placentation. These comprise whales, camels, pigs, ruminants, horses and pangolins. In contrast, nearly all carnivores have endotheliochorial placentation, whilst bats have endotheliochorial or hemochorial placentas. Also included in Laurasiatheria are a number of insectivores that have many conserved morphological characters; none of these has epitheliochorial placentation. Consideration of placental type in relation to the findings of molecular phylogenetics suggests that the likely path of evolution in Afrotheria was from endotheliochorial to hemochorial placentation. This is also a likely scenario for Xenarthra and the bats. We argue that a definitive epitheliochorial placenta is a secondary specialization and that it evolved twice, once in the Laurasiatheria and once in the lemurs and lorises.     

The dynamics of the autoimmune process in guinea pigs during their acquisition of an experimental neurosis

Pathogenetic role of the neuroautoimmune reactions in dynamics of the experimental neurosis development has been investigated. Application of the dynamic approach in estimation of the pathological process has permitted analyzing changes in the immunological indices in dynamics of the experimental neurosis development. The results obtained testify to that maximum content of autoantibodies to the nervous tissue, circulating immune complexes and changes in the reaction of neutrophilic injury are observed in the beginning of the experimental neurosis development.