Dental eruption sequence and eruption times in Erythrocebus patas

Erythrocebus patas has a short inter-birth interval, juveniles become independent from their mother early, females are young at first birth, and adult females have a high mortality rate. According to Schultz’s rule, the molars of fast-growing and shorter-lived primate species erupt early relative to the replacement teeth. Based on the life history of E. patas, we hypothesized that the molars would erupt before the replacement teeth and/or that the eruption time of its molars would be early. The purpose of the present study was to determine the dental eruption sequence and eruption times for E. patas and to test our hypothesis. The eruption sequence for the permanent teeth of E. patas is \frac\textM1  \textI1  \textI2  \textM2  \textP3  \textP4  [\textC  \textM3]\textM1  \textI1  \textI2  \textM2  \textP4  [\textP3  \textC]\textM3 \frac{{{\text{M1}}\;{\text{I1}}\;{\text{I2}}\;{\text{M2}}\;{\text{P3}}\;{\text{P4}}\;[{\text{C}}\;{\text{M3}}]}}{{{\text{M1}}\;{\text{I1}}\;{\text{I2}}\;{\text{M2}}\;{\text{P4}}\;[{\text{P3}}\;{\text{C}}]{\text{M3}}}} in males and \frac\textM1  \textI1  \textI2  [\textM2  \textP4  \textP3  \textC]\textM3\textM1  \textI1  \textI2  [\textM2  \textP4  \textP3  \textC]\textM3 \frac{{{\text{M1}}\;{\text{I1}}\;{\text{I2}}\;[{\text{M2}}\;{\text{P4}}\;{\text{P3}}\;{\text{C}}]{\text{M3}}}}{{{\text{M1}}\;{\text{I1}}\;{\text{I2}}\;[{\text{M2}}\;{\text{P4}}\;{\text{P3}}\;{\text{C}}]{\text{M3}}}} in females. Because these sequences constitute the general pattern seen in cercopithecines, Schultz’s rule could not be applied to E. patas. The emergence time of upper and lower first molar (M1) is earlier in E. patas than in macaques, baboons, and mandrills and is similar to that in Chlorocebus aethiops. The emergence time of deciduous upper and lower fourth premolar (dp4) is similar to that in the above-mentioned cercopithecines but is later than that in Ch. aethiops. The emergence times of upper and lower second molar (M2) and upper and lower third molar (M3) in E. patas are earlier than those in the above-mentioned cercopithecines but later than those in Ch. aethiops. However, the intervals of the emergence time between each permanent molar in E. patas are similar to those of the above-mentioned cercopithecines. The early appearance of M2 and M3 in E. patas is related to the short interval of emergence time between dp4 and M1.     

Dental eruption in afrotherian mammals

Background  

Afrotheria comprises a newly recognized clade of mammals with strong molecular evidence for its monophyly. In contrast, morphological data uniting its diverse constituents, including elephants, sea cows, hyraxes, aardvarks, sengis, tenrecs and golden moles, have been difficult to identify. Here, we suggest relatively late eruption of the permanent dentition as a shared characteristic of afrotherian mammals. This characteristic and other features (such as vertebral anomalies and testicondy) recall the phenotype of a human genetic pathology (cleidocranial dysplasia), correlations with which have not been explored previously in the context of character evolution within the recently established phylogeny of living mammalian clades.     

Dental eruption schedules of wild and captive baboons

Dental eruption schedules previously used to age wild baboons have in the past derived from studies of captive animals housed under standard conditions and fed standard laboratory diets. This paper reports for the first time eruption schedules derived from wild baboons, the yellow baboons (Papio hamadryas cynocephalus) of Mikumi National Park, Tanzania, and compares these schedules with those of other baboon subspecies inhabiting both similar and dissimilar environments. Eighteen males and twelve females from the Viramba groups, ranging in age from 21 to 103 months, were trapped, and dental impressions and notes were made of the state of eruption of each tooth. Eruption of all teeth were delayed at Mikumi relative to the baboon standards derived from the captive animals at the Southwest Foundation for Biomedical Research, San Antonio, Texas. Teeth of the canine-premolar 3 complex and third molars were most delayed, erupting up to a year and a half later than their counterparts from captive animals. Comparison with data on hamadryas baboons from Erer-Gota in Ethiopia revealed that both the hamadryas and yellow subspecies of baboons, with different genetic backgrounds and living under markedly different environmental conditions, followed the same schedule. This constancy of developmental schedules suggests that these Mikumi data may reasonably be used as standards for other wild baboon populations and that acceleration of dental maturation, as well us maturation of other somatic systems in captivity, is another manifestation of the short-term adaptive plasticity of the baboon species as a whole.     

Dental agenesis as evidence of possible genetic isolation in the colobine monkey,Rhinopithecus roxellana

In a sample of 24 skulls of the rare colobine monkey of China,Rhinopithecus roxellana, agenesis of the permanent upper third premolar was observed in 8 specimens (33%). Two of the individuals (8% of the sample) showed unilateral agenesis, while six (25%) showed bilateral agenesis. All of the affected individuals appear to have originated from two areas in central Sichuan Province in China, Moupin (Baoxing) and Wen Chuan, that lie approximately 120 km apart on the western rim of the Sichuan Basin. In this species agenesis of the upper third premolar was generally accompanied by rotation of the upper fourth premolar, but not by any other observable variation in tooth size, morphology, or number. Further, dental agenesis in this species appears to have had no effect craniofacial morphology. In certain human populations, a high prevalence of dental agenesis has been associated with small population effects and genetic isolation. Premolar agenesis inR. roxellana can probably be traced to a similar origin. Reconstruction of the evolutionary history of the species indicates that a severe reduction of the geographic range of the species occurred as a result of climatic deterioration during the Late Pleistocene. Although large numbers of populations appear to have become extinct, others survived to give rise to the modern populations of the species that inhabit China today. The two populations showing a high prevalence of premolar agenesis appear to have originated from one that passed through a population bottleneck and suffered the consequences of founder effect in the Late Pleistocene. This interpretation is supported by evidence of dental agenesis in a population of an insectivore species from the same region and by the fact that premolar agenesis is not found in any of the other species ofRhinopithecus. There is no evidence to support the interpretation that dental agenesis inR. roxellana is due to natural selection, mutation or an evolutionary force other than a small population effect.     

Dental microwear and diet in Venezuelan primates.

Recent microwear analyses have demonstrated that wear patterns can be correlated with dietary differences. However, much of this work has been based on analyses of museum material where dates and locations of collection are not well known. In view of these difficulties, it would be desirable to compare microwear patterns for different genera collected from the same area at the same time. The opportunity to do this was provided by the collections of the Smithsonian Venezuelan Project (Handley, 1976), in which multiple primate genera were collected from the same humid tropical forest sites within the same month. The monkeys represent a wide range of dietary preferences, and include Saimiri, Cebus, Chiropotes, Ateles, Aotus, Pithecia, and Alouatta. As in previous microwear analyses, epoxy replicas were prepared from dental impressions, as described by Rose (1983) and Teaford and Oyen (1989). Two micrographs were taken of facet 9 on an upper second molar of each specimen. Computations and analyses were the same as described by Teaford and Robinson (1989). Results reaffirm previously documented differences in dental microwear between primates that feed on hard objects versus those that do not--with Pithecia and Alouatta at the extremes of a range of microwear patterns including more subtle differences between species with intermediate diets. The subtle microwear differences are by no means easy to document in museum samples. However, additional results suggest that 1) the width of microscopic scratches may be a poor indicator of dietary differences, 2) large and small pits may be formed differently, and 3) there are very few seasonal differences in dental microwear in the primates at these humid tropical forest sites.     

Cross-species handling of colobine infants

At Tiwai Island, Sierra Leone, several instances of red colobus (Procolobus badius) adults handling white infants of black-and-white colobus monkeys (Colobus polykomos) were observed. These observations are described and their significance is discussed.     

Food partitioning among Malagasy primates

Summary Food partitioning among lemurs was studied in relation to food patch size and plant chemistry in the eastern rainforest and a western deciduous forest of Madagascar. Patch size (i.e. crown diameter of food trees) is significantly correlated with group body weight of different lemur species. But intraspecific variability is high and prevents effective species separation. Chemical analyses of more than 400 plant parts eaten by seven different lemur species revealed major differences in their food choice with respect to protein concentrations, condensed tannins and alkaloids. Among the leaf eating lemurs discriminant analysis segregates three groups à two species based on chemical characteristics of their food. Whereas differences in food chemistry are pronounced between groups they are lacking between the two species within each group. The two species of each group avoid interference competition by different activity rhythms. Actual competition for slowly renewable resources such as leaves and fruit, however, can not be reduced by different activities. Here interspecific differences in gross categories of food, food species composition and different habitat utilization due to other constraints may contribute to the possible coexistence of species. Thus interspecific differences in food selection in relation to primary and secondary plant chemicals is an integrated part of the mechanisms allowing several primate species to coexist in sympatry.     

Digestive strategy of the asian colobine genusTrachypithecus

The Asian colobines,Trachypithecus obscurus andT. cirstantus, eat plant-based diets containing 55–80% leaves. The structural polysaccharides in leaves and other plant parts require microbial fermentation before they can be used as an energy source by the monkeys. The major compartments of the gastro-intestinal tract ofTrachypithecus are a voluminous haustrated stomach, a long small itnestine and capacious haustrated hindgut, all of which contribute to the digestive strategy of these two species. Results of digesta marker passage studies indicate there is prolonged retention of digesta for fermentation in both the stomach and haustrated colon. The digestive strategy of these colobines is defined as gastro-colic fermentation, unlike that of other forestomach fermenters in which the hindgut fermentation is of secondary importance.     

Avoiding commitment: cathemerality among primates

Cathemeral animals distribute their activity more or less uniformly between the dark and light phases of the 24-hour day. This activity pattern is quite widely observed among major mammal taxa, although the number of species involved is relatively low. Among primates, cathemerality is seen principally, though not uniquely, in the strepsirhine (“lower primate”) family Lemuridae; it is ubiquitous in the genus Eulemur, among species of which it seems to be a stable activity pattern with a history going back at least 8 - 12 million years. Nocturnal primates have visual systems that accentuate sensitivity to light over visual acuity, showing large cornea size, high rod:cone ratios and large numbers of photoreceptors relative to ganglion cells. Diurnal forms do the reverse, while Eulemur species are intermediate in these respects, suggesting substantial accommodation of the visual system to the cathemeral lifestyle. Studies of one Eulemur species have revealed that its cathemerality is underpinned by a robust endogenous circadian timing mechanism with a free-running periodicity of over 25 hours. The lemurs appear to be entrained to the 24-hour day by the light/dark cycle, plausibly with dusk as the primary zeitgeber. The causes of cathemerality have been sought in such environmental influences as predator avoidance, energy conservation, dietary quality, and interspecies feeding competition. All of these factors seem to be relevant to the cathemeral lifestyle, but none appears to be a crucial determinant. Nothing is known of the underlying neural mechanisms that facilitate the lemurs' accommodation to the extremes to which 24-hour activity exposes them.     

Dental eruption in captive-bornCebus apella: From birth to 30 months old

This work reports on the ages of gingival eruption of deciduous and permanent teeth observed from the time of birth until 30 months old, captive-born individuals. All of the animals were born with the protrusive di₁ already through the gingival border. The dmp⁴ were the last teeth of the deciduous series which emerged at 24.5±3.11 weeks in the males and 27.8±2.95 weeks in the females. Significant sexual differences were found between the eruption period of the dpm₂, dmp⁴ (p<0.05), and dpm₄ (p<0.01), with the males being more precocious than the females. The first permanent tooth that emerged, usually, was the M₁ at 13.50±2.12 months in the males, and 14.00±0.82 months in the females. At 30 months of age, not one individual had replaced his deciduous canine or premolar teeth with the permanent ones, and, moreover, the M ₃ ³ had not yet emerged.     

Techniques for determining protein sequence evolution applied to primates

Each amino acid in a protein is considered to be an individual, mutable characteristic of the species from which the protein is extracted. For a branching tree representing the evolutionary history of the known sequences in different species, our computer programs use majority logic and parsimony of mutations to determine the most likely ancestral amino acid for each position of the protein at each node of the tree. The number of mutations necessary between the ancestral and present species is summed for each branch and the entire tree. The programs then move branches to make many different configurations, from which we select the one with the minimum number of mutations as the most likely evolutionary history. We used this method to elucidate primate phylogeny from sequences of fibrinopeptides, carbonic anhydrase, and the hemoglobin beta, delta and alpha chains. All available sequences indicate that the early Pongidae had diverged into two lines before the divergence of an ancestor for the human line alone. We have constructed some probable ancestral sequences at major points during primate evolution and have developed tentative trees showing the order of divergences and evolutionary distances among primate groups. Further questions on primate evolution could be answered in the future by the detemination of the appropriate sequences.     

Mitochondrial data support an odd-nosed colobine clade

To obtain a more complete understanding of the evolutionary history of the leaf-eating monkeys we have examined the mitochondrial genome sequence of two African and six Asian colobines. Although taxonomists have proposed grouping the "odd-nosed" colobines (proboscis monkey, douc langur, and the snub-nosed monkey) together, phylogenetic support for such a clade has not been tested using molecular data. Phylogenetic analyses using parsimony, maximum likelihood, and Bayesian methods support a monophyletic clade of odd-nosed colobines consisting of Nasalis, Pygathrix, and Rhinopithecus, with tentative support for Nasalis occupying a basal position within this clade. The African and Asian colobine lineages are inferred to have diverged by 10.8 million years ago (mya or Ma). Within the Asian colobines the odd-nosed clade began to diversify by 6.7 Ma. These results augment our understanding of colobine evolution, particularly the nature and timing of the colobine expansion into Asia. This phylogenetic information will aid those developing conservation strategies for these highly endangered, diverse, and unique primates.     

Dental formulae and dental eruption patterns in Parapithecidae (Primates, Anthropoidea)

The eruption sequence for the lower teeth of Apidium phiomense based on 18 juvenile specimens is dP3, dP4, M1, M2, P2, P4, (P3, M3), C. Only five specimens of Parapithecus grangeri show developing lower teeth. P2, M1, and M2 all erupted before P3 and P4; C and M3 were the last cheek teeth to erupt. Late eruption of the lower canines in parapithecids is a possible shared derived resemblance linking these species with Anthropoidea and Adapidae and distinguishing both from Omomyidae, Tarsiidae, and tooth-combed lemurs. Late eruption of M3 in parapithecids is a shared derived resemblance with Anthropoidea alone. The lower dental formula of Apidium phiomense is confirmed as 2 X 1 X 3 X 3 by additional specimens which show the incisors. Based in part on tooth socket counts, the deciduous lower dental formula was 2 X 1 X 3. New specimens of Parapithecus grangeri now demonstrate an adult mandibular dental formula of 0 X 1 X 3 X 3 (not 2 X 1 X 3 X 3 as previously thought) and a juvenile formula of 1 X 1 X 3. The number of incisors possessed by Parapithecus fraasi is again open to debate. Material is insufficient to judge whether this species had a pair of incisors in each lower jaw quadrant, by analogy with Apidium, or had undergone reduction to just one incisor. In any event, the presence of two incisors in another parapithecid Apidium shows anterior tooth reduction of Parapithecus grangeri occurred independent of, and should not be considered a shared derived similarity with, Tarsiidae, as was once thought.     

The function of peaceful post-conflict contacts among primates

Reconciliation has been the subject of considerable research in the last decade, and researchers have demonstrated that in many species of Old World monkeys and apes former opponents are more likely to engage in friendly interactions in the minutes that follow conflicts than they are at other times.de Waal has suggested that the function of these interactions is to mend relationships that have been damaged by conflict. Although peaceful post-conflict interactions are thought to have long-term effects upon the nature of social relationships, behavioral evidence presently indicates that the effects of these interactions may be limited to the post-conflict period. Theoretical considerations also raise some doubts about whether the relationship-repair hypothesis is cogent. Data that demonstrate that peaceful post-conflict interactions facilitate peaceful interactions and relieve victim's uncertainty and anxiety about whether conflict will be continued suggest that peaceful post-conflict interactions may be a means to reestablish contact with former opponents. Thus, they appear to function as predictive signals that the actor is going to stop fighting and behave peacefully. Such signals may be important in a broad range of social contexts.     

Grooming reciprocation among female primates: a meta-analysis

The theory of reciprocal altruism offers an explanation for the evolution of altruistic behaviours among unrelated animals. Among primates, grooming is one of the most common altruistic behaviours. Primates have been suggested to exchange grooming both for itself and for rank-related benefits. While previous meta-analyses have shown that they direct their grooming up the hierarchy and exchange it for agonistic support, no comprehensive evaluation of grooming reciprocation has been made. Here we report on a meta-analysis of grooming reciprocation among female primates based on 48 social groups belonging to 22 different species and 12 genera. The results of this meta-analysis showed that female primates groom preferentially those group mates that groom them most. To the extent allowed by the availability of kinship data, this result holds true when controlling for maternal kinship. These results, together with previous findings, suggest that primates are indeed able to exchange grooming both for itself and for different rank-related benefits.