Buccal enamel microwear variability in Cercopithecoidea Primates as a reflection of dietary habits in forested and open savanna environments

Dental microwear analysis has proved to be a good indicator of diet and dietary related behaviour in modern humans, fossil hominids and primates. The composition of the diet and the presence of dust and other abrasive particles, are related to microwear rates on the buccal enamel surfaces of molar teeth. Plant food materials such as leaves or stems include phitoliths in larger quantities than fruits or meat. These particles may scratch the enamel surface of teeth during mastication producing a microwear pattern that may be indicative of food choice and food preferences within primate species. In this study we present a dental microwear analysis of extant Cercopithecoidea primates, based on the analysis of more than 200 dental casts obtained from the osteological collection of the National Museum of Kenya (NMK). Specific, sub-specific and also ecological differences are shown to underlie the buccal microwear variability observed within the studied sample

Tooth replication techniques, SEM imaging and microwear analysis in Primates: methodological obstacles

Dental microwear analyses are among the most significant techniques though which a researcher can make dietary and ecological inferences from primate fossil specimens. Hard particles, such as plant phytoliths or silica-base sands, can scratch tooth enamel surfaces during food mastication producing a dietary specific pattern of microwear on the enamel surface. The density, axis length and orientation of microwear features, either striations or pits, are highly informative of dietary habits in both extant and fossil primates. The analysis of tooth enamel surfaces requires the use of scanning electron microscopy (SEM) techniques, because of its high resolution power, including gold-coating of teeth for observation. Problems arise when specimens to be analysed are unique and there is no possibility of a direct observation with an environmental microscope. Negative moulds must then be made and silicone-base components are indicated for high quality replication of enamel surfaces. A positive cast needs to be obtained, and epoxy-base resins are frequently used for their good quality and durability. However, successive silicon and epoxy replications result in the loosing of surface detail and precision. Surface observation errors can also be caused be the SEM technology itself, especially if back-scattered electrons are used instead of secondary electrons for maximizing the topographical information of enamel images. This paper reviews the most commonly used methodological approaches to tooth moulding and casting, comparing SEM micrographs of casts with actual tooth surfaces, and contrasting the reliability of SEM images for dietary interpretation of tooth microwear in both extant and fossil primates

Age and individual foraging behavior predict tooth wear in Amboseli baboons

Teeth represent an essential component of the foraging apparatus for any mammal, and tooth wear can have significant implications for survival and reproduction. This study focuses on tooth wear in wild baboons in Amboseli, southern Kenya. We obtained mandibular and maxillary tooth impressions from 95 baboons and analyzed digital images of replicas made from these impressions. We measured tooth wear as the percent dentine exposure (PDE, the percent of the occlusal surface on which dentine was exposed), and we examined the relationship of PDE to age, behavior, and life history variables. We found that PDE increased significantly with age for both sexes in all three molar types. In females, we also tested the hypotheses that long-term patterns of feeding behavior, social dominance rank, and one measure of maternal investment (the cumulative number of months that a female had dependent infants during her lifetime) would predict tooth wear when we controlled for age. The hypothesis that feeding behavior predicted tooth wear was supported. The percent of feeding time spent consuming grass corms predicted PDE when controlling for age. However, PDE was not associated with social dominance rank or maternal investment

Testing dietary hypotheses of East African hominines using buccal dental microwear data

Abstract There is much debate on the dietary adaptations of the robust hominin lineages during the Pliocene-Pleistocene transition. It has been argued that the shift from C3 to C4 ecosystems in Africa was the main factor responsible for the robust dental and facial anatomical adaptations of Paranthropus taxa, which might be indicative of the consumption of fibrous, abrasive plant foods in open environments. However, occlusal dental microwear data fail to provide evidence of such dietary adaptations and are not consistent with isotopic evidence that supports greater C4 food intake for the robust clades than for the gracile australopithecines. We provide evidence from buccal dental microwear data that supports softer dietary habits than expected for P. aethiopicus and P. boisei based both on masticatory apomorphies and isotopic analyses. On one hand, striation densities on the buccal enamel surfaces of paranthropines teeth are low, resembling those of H. habilis and clearly differing from those observed on H. ergaster, which display higher scratch densities indicative of the consumption of a wide assortment of highly abrasive foodstuffs. Buccal dental microwear patterns are consistent with those previously described for occlusal enamel surfaces, suggesting that Paranthropus consumed much softer diets than previously presumed and thus calling into question a strict interpretation of isotopic evidence. On the other hand, the significantly high buccal scratch densities observed in the H. ergaster specimens are not consistent with a highly specialized, mostly carnivorous diet; instead, they support the consumption of a wide range of highly abrasive food items

Enterrament d'època tardoromana d'un macaco amb 'aixovar' al jaciment de Les Colomines (Llívia, La Cerdanya)

[spa] El yacimiento de Les Colomines se ubica en una franja de terreno situada al pie del puig del Castell, al norte de la villa de Llivia (La Cerdanya). La intervención arqueológica se efectuó entre 1997 y 2001 como consecuencia de un proyecto de urbanización. En esta última se descubrió la tumba de un macaco (Macaca sylvanus), junto a un 'ajuar' asociado al primate, de piezas metálicas pertenecientes a otros tantos cinturones de tradición militar romana bajoimperial. La relación estratigráfica de la tumba y el material apuntan una cronoiogia, para el enterramiento, de siglo V-VI La tumba se relaciona con la fase 3 y última de la ocupación del asentamiento, caracterizada por la compartimentación de una planta inicial regular perteneciente a un gran edificio público levantado durante los siglos I y II. En relación al individuo en cuestión, se llevó a cabo un estudio osteológico y biométrico, lo que permitió caracterizarlo a nivel de especie, edad y sexo, asi como un análisis del patrón de microestriación dentaria, y paralelamente un profundo estudio del contexto histórico.[eng] In 2001 was discovered, in the site of Les Colomines (Llívia, Cerdanya), the remains of an african monkey's burial, a macaque (Macaca sylvanus), containing the skeleton of the animal, with some objects. This group consisted basically in decorated metalic pieces; we can speak, among them, about some bronze military belt fittings, used in the Late Roman Empire. After the excavation, we agree to think al1 this objects were disposed in the moment of the burial. Chronologically: this whole belongs to the V-VI centuries A.O. (Studying this material and the stratigraphic relations of this structure, we can associate this tomb with the third phase of occupation of Les Colomines. This settlement caracterized by important structures, including habitations, and materiais (specially ceramics, but also an epigraphic lnscription), was a public building (maybe a forum), during the romanization period and after (1-11 centuries A.O.). in their third phase, along with the tomb, we discovered an important reestructuration of the buildings, anda group of 204 coins from the period. The interpretation of the tomb and its caracteristics can be associated with diferents military struggles to controi the strategic Pyrennes in the last stages of Roman control of Hispania, between different emperors, and between the Roman Imperial Army and the Barbarians also. Possibly this macacus belonged to an official or a general. Once recuperated, osteological and biometric studies have been made with the bones, and complementary studies about the age, sex, and teeth also. No other exemple has been discovered in the classical world with this caracteristics

Buccal dental microwear analyses support greater specialization in consumption of hard foodstuffs for Australopithecus anamensis

Molar occlusal microwear texture and anisotropy analyses of 3 Australopithecus anamensis fossil specimens have shown complexity values similar to those of Au. afarensis, indicating that neither of these hominin species had a diet dominated by hard food. However, many researchers have suggested that these were some of the earliest hominins to have such diets. Here we examine buccal microwear patterns of 5 Au. anamensis, 26 Au. afarensis, 48 Hominoidea and 80 Cercopithecoidea primate specimens for independent evidence of dietary adaptations of Au. anamensis. The buccal microwear results obtained suggest that the diet of Au. anamensis relied heavily on hard, brittle food, at least seasonally. This is similar to the diet of the extant Cercopithecoidea primates, including Papio anubis and Chlorocebus aethiops, both of which live in wooded, seasonal savannah environments and have diets that include fruit and grasses, but also underground storage organs (USOs), such as corms or blades, as well as leaves and seeds, and also Mandrillus and Cercocebus, from forested environments with frugivorous-granivorous diets. Furthermore, the buccal microwear patterns of Au. anamensis and Au. afarensis clearly differed -in clear contrast to occlusal enamel texture observations-, which support previous dietary interpretations based on both anatomical and palaeocological reconstructions

Dominance rank but not body size influences female reproductive success in mountain gorillas

According to life history theory, natural selection has shaped trade-offs for allocating energy among growth, reproduction and maintenance to maximize individual fitness. In social mammals body size and dominance rank are two key variables believed to influence female reproductive success. However, few studies have examined these variables together, particularly in long-lived species. Previous studies found that female dominance rank correlates with reproductive success in mountain gorillas (Gorilla beringei beringei), which is surprising given they have weak dominance relationships and experience seemingly low levels of feeding competition. It is not currently known whether this relationship is primarily driven by a positive correlation between rank and body size. We used the non-invasive parallel laser method to measure two body size variables (back breadth and body length) of 34 wild adult female mountain gorillas, together with long-term dominance and demography data to investigate the interrelationships among body size, dominance rank and two measures of female reproductive success (inter-birth interval N = 29 and infant mortality N = 64). Using linear mixed models, we found no support for body size to be significantly correlated with dominance rank or female reproductive success. Higher-ranking females had significantly shorter inter-birth intervals than lower-ranking ones, but dominance rank was not significantly correlated with infant mortality. Our results suggest that female dominance rank is primarily determined by factors other than linear body dimensions and that high rank provides benefits even in species with weak dominance relationships and abundant year-round food resources. Future studies should focus on the mechanisms behind heterogeneity in female body size in relation to trade-offs in allocating energy to growth, maintenance and lifetime reproductive success

Nota metodológica: Alteración del patrón de microestriación dentaria por el efecto wrinkle.

Se describe el efecto wrinkle observado por primera vez sobre moldes dentarios realizados con resinas epoxy y metalizados en oro para su observación mediante microscopía electrónica de barrido (SEM). Con el fin de determinar en qué medida puede afectar al análisis del patrón de microestriación vestibular, se analizan dos muestras dentales de tres especies de Hominoideos, una de ellas incluyendo moldes con presencia de"aguas" relacionadas con el proceso de metalización. Se observa un descenso marcado de la variabilidad del patrón de microestriación dentaria anque las diferencias entre las dos muestras por especie no son estadísticamente significativas. El efecto wrinkle reduce significativamente el porcentaje de clasificación correcta de las especies analizadas a partir del patrón de microestriación y rugosidad dental utilizando un Análisis Discriminante. Se aconseja evitar la inclusión de las muestras afectadas por aguas en los estudios del patrón de microestriación dentaria

New evidence and interpretation of subvertical grooves in eandertal teeth from Cueva de Sidrón (Spain) and Figueira Brava (Portugal)

Interproximal tooth wear is caused by tooth-to-tooth rubbing that results in the formation of flat wear surfaces characterized by an intense pattern of enamel pitting caused by prism-plucking. The rate of wear of such surfaces depends on the forces involved in food processing and chewing. In some instances, the interproximal wear facets, mainly of molar teeth, show a number of subvertical grooves with a nearly vertical direction. These grooves are mostly present in Neanderthal teeth, but have also been described in some African fossil teeth and in European Homo heidelbergensis, as well as in several modern hunter-gatherer populations, such as Australian Aborigines. Subvertical grooves have seldom been attributed to taphonomic processes, although most probably they are caused by natural biomechanical processes during mastication of hard objects included in the diet. They have also been associated to acidic dietary habits given their radial disposition and their inter-digitalisation. The present study analyses the subvertical grooves observed in the Neanderthal dentition of Cueva de Sidrón (Spain). Comparisons are made with the similar interproximal grooves pattern observed in the Neanderthal specimen from Figueira Brava (Portugal) and some remains of H. heidelbergensis from Sima de los Huesos (Spain). Other cases have been described for the Neanderthal sites of Genay and Le Fate (France). The results obtained allow discarding a post-mortem origin of these structures, the most probable cause of the subvertical grooves being natural biomechanical chewing processes combined with some dietary habits indicative of hard plant foods ingestion

El Patró de microestriació dental de primats "Catarrhini": un model ecològic per primats fòssils i homínids

[cat] Aquest treball proposa una metodologia que permet l'obtenció d'informació a nivell microscòpic de les corones dentals sense una excessiva manipulació dels espècimens originals dipositats en diverses col·leccions osteològiques. La tècnica consisteix en la realització de motlles dentals d'alta resolució i la posterior obtenció de positius amb resina o poliuretà, per disposar de rèpliques d'alta qualitat. Així mateix s'han considerat diversos aspectes tècnics en la utilització del Microscopi Electrònic de Rastreig (SEM) i els preparatius previs de la mostra per el correcte estudi de les superfícies d'esmalt. L'estudi del patró de microestriació dental en primats Cercopithecoidea s'ha centrat en diverses espècies dels gèneres Papio, Cercopithecus i Colobus. Els resultats indiquen, en primer lloc, que únicament un baix percentatge d'individus de les col·leccions presenten una bona preservació de les dents, amb patrons de microestriació analitzables, tot i que de manera desigual en funció de l'espècie. Les anàlisis dels patrons de microestriació ben preservats mostren grans diferències entre les espècies analitzades. Pel que fa a les anàlisis de les estries dels primats Hominoidea, s'ha descrit una gran homogeneïtat general interespecífica, tot i que també hi ha grans diferències en els patrons a nivell poblacional i relacionades amb qüestions ecològiques i estacionals en el consum d'aliments clau durant les èpoques d'escassetat d'aliments. El conjunt de la variabilitat dels patrons de microestriació dental dels primats Catarrhini actuals s'ha utilitzat com a marc de referència per comparar el patró de microestriació d'algunes espècies de primats fòssils amb l'objectiu d'interpretar la seva possible alimentació. Una anàlisis de tota la variabilitat mostra que els primats del Miocè, Dryopithecus laietanus i Oreopithecus bambolii, difereixen molt en els patrons de microestriació dental. El 80% dels Dryopithecus analitzats es van classifica com Gorilla, amb una alta probabilitat de classificació. Per altra banda, l'únic espècimen de Oreopithecus que va donar resultats fiables es va classificar amb els Papio. La caracterització de la dieta d'ambdues espècies fòssils és, doncs, contradictòria amb les conclusions d'estudis previs basats únicament en la morfologia dental. La gran similitud de Dryopithecus laietanus i Gorilla gorilla indica que aquest primat podria haver consumit recursos tròfics abrasius, com plantes herbàcies, fulles o medul·les, tot i que no es pot descartar el consum de fruits. Oreopithecus, malgrat la reduïda mostra analitzada, sembla presentar un patró de microestriació dental propi d'un primat de zones obertes amb un consum de recursos més generalista, però descartant la hipòtesis que hagués consumit fulles. L'apartat final de la tesi estudia la variabilitat poblacional dels Hominoidea, i com aquesta pot ajudar a interpretar l'alimentació de l'homínid africà Australopithecus afarensis. Els resultats indiquen que les poblacions de goril·les del Congo són les que presenten un patró de microestriació més diferenciat. Els goril·les i els ximpanzés del Camerún formen un grup molt homogeni i posseeixen patrons de microestriació dental molt semblants, possiblement perquè habiten el mateix ecosistema i l'exploten de manera molt similar. Les anàlisis discriminants de totes les variables quantitatives del patró de microestriació dental van permetre classificar als homínids. La màxima similitud la van presentar amb els papions, seguida dels goril·les del Camerún; però cap d'ells ho va fer com Pan troglodytes verus o els goril·les del Congo, que habiten entorns ecològics en mosaic on consumeixen una gran proporció d'aliments clau fibrosos de manera estacional. Aquests resultats suggereixen que aquests homínids no van explotar recursos estacionals molt fibrosos però, contràriament, presentarien una dieta basada en el consum d'aliments de baixa qualitat durant gran part de l'any, com farien els papions actuals i, així mateix, un consum de recursos vegetals semblants als utilitzats pels goril·les.[eng] The analysis of dental microwear is one of the techniques most used for the interpretation of the diet of hominids and fossil primates. The teeth of the primates are a source of very important information, not only for the studies of microwear, but for multiple studies of compared morphology or taxonomy. The quantification of dental microwear patterns from SEM images is done by using semiautomatic procedures, so the measurement of the microstriations has an associate inevitable mistake that depends on many intrinsic factors of the image, but also related to the observer. The present study approaches the quantification of these errors of measurement at interobserver and intraobserver levels. The study of the variability of dental microwear in Cercopithecoidea primates has been based on several species: Papio, Cercopithecus and Colobus. They can be considered a good group of primates to see if the ecological differences are related to dental microwear pattern. The whole variability of the dental microwear patterns including all Catarhini (Cercopithecoidea and Hominoidea) has been used as a reference for comparing the dental microwear of some fossil primates with the aim to interpret its possible diets. An analysis of the whole variability shows that the Miocene primates, Dryopithecus laietanus and Oreopithecus bambolii, differ very much in dental microwear patterns. 80% of the analyzed Dryopithecus laietanus are classified as Gorilla gorilla, but Oreopithecus bambolii is classified as Papio anubis. Finally, dental microwear variability of primates is used for the interpretation of Australopithecus afarensis diet and its ecological reconstruction. Results indicates that hominid microwear pattern are classified as baboons, followed by the gorillas from Cameroon; but none of them did it as Pan troglodytes verus or gorillas from Congo, which inhabit in a mosaic environments and consume a great proportion of keystone and fibrous food seasonally. These results suggest that these hominids did not exploit seasonally very fibrous resources but, in contrast they would present a diet based on a food consumption of low quality during great part of the year