Orang-like manual adaptations in the fossil hominoid Hispanopithecus laietanus: first steps towards great ape suspensory behaviours

Morphological and biometrical analyses of the partial hand IPS18800 of the fossil great ape Hispanopithecus laietanus (=Dryopithecus laietanus), from the Late Miocene (about 9.5Ma) of Can Llobateres (Catalonia, Spain), reveal many similarities with extant orang-utans (Pongo). These similarities are interpreted as adaptations to below-branch suspensory behaviours, including arm-swinging and clambering/postural feeding on slender arboreal supports, due to an orang-like double-locking mechanism. This is confirmed by the long and highly curved phalanges of Hispanopithecus. The short and stout metacarpals with dorsally constricted heads, together with the dorsally extended articular facets on proximal phalanges, indicate the persistence of significant degrees of palmigrady. A powerful grasping capability is indicated by the great development of basal phalangeal tubercles, the marked insertions for the flexors on phalangeal shafts and the large pits for the collateral ligaments. The morphology of the Hispanopithecus long bones of the hand indicates a unique positional repertoire, combining orthogrady with suspensory behaviours and palmigrade quadrupedalism. The retention of powerful grasping and palmigrady suggests that the last common ancestor of hominids might have been more primitive than what can be inferred on the basis of extant taxa, suggesting that pronograde behaviours are compatible with an orthograde bodyplan suitable for climbing and suspension.     

Does skeletal anatomy reflect adaptation to locomotor patterns? cortical and trabecular architecture in human and nonhuman anthropoids

Although the correspondence between habitual activity and diaphyseal cortical bone morphology has been demonstrated for the fore- and hind-limb long bones of primates, the relationship between trabecular bone architecture and locomotor behavior is less certain. If sub-articular trabecular and diaphyseal cortical bone morphology reflects locomotor patterns, this correspondence would be a valuable tool with which to interpret morphological variation in the skeletal and fossil record. To assess this relationship, high-resolution computed tomography images from both the humeral and femoral head and midshaft of 112 individuals from eight anthropoid genera (Alouatta, Homo, Macaca, Pan, Papio, Pongo, Trachypithecus, and Symphalangus) were analyzed. Within-bone (sub-articular trabeculae vs. mid-diaphysis), between-bone (forelimb vs. hind limb), and among-taxa relative distributions (femoral:humeral) were compared. Three conclusions are evident: (1) Correlations exists between humeral head sub-articular trabecular bone architecture and mid-humerus diaphyseal bone properties; this was not the case in the femur. (2) In contrast to comparisons of inter-limb diaphyseal bone robusticity, among all species femoral head trabecular bone architecture is significantly more substantial (i.e., higher values for mechanically relevant trabecular bone architectural features) than humeral head trabecular bone architecture. (3) Interspecific comparisons of femoral morphology relative to humeral morphology reveal an osteological \"locomotor signal\" indicative of differential use of the forelimb and hind limb within mid-diaphysis cortical bone geometry, but not within sub-articular trabecular bone architecture.     

ORIGINAL ARTICLE: Leptin associations with age,weight, and sex among chimpanzees (Pan troglodytes)

Background Leptin is a hormone secreted primarily by adipocytes, a lipostatic signal to the hypothalamus, and is often correlated with adiposity. Associations between leptin, age, and development are unknown in human’s closest evolutionary relative, the common chimpanzee (Pan troglodytes). Methods Serum leptin was assessed cross sectionally in association with age, weight, and sex in healthy captive chimpanzee males (n = 47) and females (n = 49) to test hypotheses related to predicted differences in leptin levels with body mass, development, and sexual dimorphism. Results Leptin increased with age and weight among females, but not in males. Leptin was overall higher in females compared to males. Conclusions Sex differences in leptin were most evident during adolescence and adulthood, despite similar increases in weight in both sexes indicating that sexual maturation is a key divergence point for differential somatic investment in adiposity and leptin levels between male and female chimpanzees.     

Intestinal Parasites in Gorillas,Chimpanzees, and Humans at Mondika Research Site,Dzanga-Ndoki National Park,Central African Republic

We report prevalences and eggs/protozoa per g (EPG; PPG) of helminths and protozoa in gorillas, chimpanzees, agile mangabeys, indigenous Ba'Aka and Bantu, and western researchers at a remote field site in the Central African Republic. We examined fecal samples for eggs, larvae, proglottids, cysts, amoeba, trophozoites, and flagellates. For helminths, strongylates were most prevalent, infecting 82–94% of nonhuman primates (NH) and 30–93% of human (H) groups, followed by ascaroids (14–88% NH; 0–15% H), and threadworms (0–22% NH; 0–29% H). For protozoa, Entamoeba histolytica (2–100% NH; 33–52% H) and trichomonads (11–88% NH; 0–54% H) were most prevalent. Among gorilla samples (n = 156) there were significant age/sex differences in EPG/PPG for strongylates, threadworms, Entamoeba histolytica, and trichomonads, with infants exhibiting the highest mean EPG/PPG for all parasites except trichomonads. Between group analyses revealed that the Ba'Aka had significantly higher mean EPG of strongylates, ascaroids and threadworms than all other primate groups, except the mangabeys. For Entamoeba histolytica, E. coli, Balantidium coli, and Iodamoeba butschlii, the agile mangabeys had significantly higher mean PPG than other groups; for trichomonads, the chimpanzees, and mangabeys had the highest mean PPG. Relative to other African ape sites, the gorillas and chimpanzees at Mondika appear to have high prevalences of intestinal parasites. This may be the result of the high proportion of swamp and seasonally flooded areas, which provide optimal viability for parasite eggs and ova. At Mondika, the significantly higher parasite levels of Ba'Aka probably result from more traditional methods of hygiene and lack of available medical treatment. All workers at research sites should be monitored and treated to minimize cross-transmission between humans and local fauna.     

Long bones of the primate upper limb: Monomorphic or dimorphic?

An important debate has been taking place during the last few years concerningAustralopithecus afarensis: can the Hadar sample be ascribed to one highly dimorphic species or should it be separated into two distinct taxa? A similar problem occurs with the Middle Miocene cercopithecoids from East Africa: does this material belong to one dimorphic group or can we recognize two different taxa? The study of the long bones of the upper limb of many extant primates suggests that the extremities in different taxa are very distinctive but that within taxa the joints are weakly or are not morphologically dimorphic although they can be markedly size dimorphic. The main shape and size differences which can be ascribed to sexual dimorphism occur in the shafts of the long bones. Examinations have been made inHomo, Pan, Gorilla, Pongo, Hylobates, Alouatta, Cebus, Saimiri, Ateles, Nasalis, Presbytis and some Cercopithecinae. It appears, then, that the extremities of the bones are shape monomorphic. If the same relationships occurred in the fossil record, then the differences observed in the hominid fossil elbow joints at Hadar suggest that at least two different taxa are represented in the collection. In addition, among the cercopithecoid material assigned toVictoriapithecus from Maboko and Nyakach in East Africa, we recognize two distinct elbow morphologies indicating that two different taxa occur in the localities.     

A reassessment of living hominoid postcranial variability: implications for ape evolution

In an analysis of hominoid postcranial variation, 'Evol. Anthrop. 6 (1998) 87' argued that many purportedly unique features of the hominoid postcranium are actually much more variable than previously reported and in many instances overlap with both suspensory (Ateles) and non-suspensory primates. Based on these results, it was concluded that parallelism in the living ape postcranium was a plausible and even likely possibility given the Miocene hominoid postcranial record. However, this analysis did not distinguish whether within-hominoid variability or overlap with non-hominoids involved one or all ape taxa, a distinction which has potentially important effects on the interpretation of results. To address this issue, primate postcranial morphometric data from the trunk and forelimb were reanalyzed using three techniques: cladistic analysis, principle components analysis, and cluster analysis. Results reveal that these postcranial characters distinguish not only suspensory and quadrupedal primates but also discriminate hominoids and Ateles from all other taxa, great apes from lesser apes and Ateles, cercopithecines from colobines, and cercopithecoids from platyrrhines. The majority of hominoid variability and overlap with Ateles occurs with Hylobates humeral head and shoulder joint characters related to brachiation. This suggests that Hylobates' specializations may skew analyses of hominoid postcranial uniqueness and variability, and that great apes are relatively similar in their postcranium.     

New material of Qatrania from Egypt with comments on the phylogenetic position of the parapithecidae (primates,Anthropoidea)

New material of the early anthropoid primate Qatrania wingi and a new species of that genus are described. Several features of the dental anatomy show that Qatrania, while quite primitive relative to other anthropoids in many ways, is most likely a parapithecid primate. The new material suggests that several dental features previously thought to ally parapithecids with the catarrhine primates were actually evolved in parallel in catarrhines and some parapithecids. Furthermore, all nonparapithecid anthropoids (including platyrrhines and catarrhines) share a suite of derived dental and postcranial features not found in parapithecids. Therefore, parapithecid origins may predate the platyrrhine/catarrhine split.     

Squirrel monkey locomotion on an inclined treadmill: Implications for the evolution of gaits

Three adult squirrel monkeys were trained to run on a motor-driven treadmill that was inclined downwardly and upwardly at 8°, 16° and 28°, and horizontally (0°). Films were used to compare the gait and kinematics of the animals across the inclines. All three animals used both lateral and diagonal sequence gaits, although the former was preferred at all but the upward 16° and 28° inclines. Cycle duration and hind limb stance and swing durations tended to increase as downward inclination decreased. Trunk inclination, except at 28° downward, tended to parallel the changes in treadmill inclination. The most dramatic and consistent change for the hind limb joint displacement patterns was that maximum extension during stance increased as the treadmill inclination increased from 28° downward to 28° upward. In contrast to an earlier study by Prost & Sussman (1969), we could find no evidence that squirrel monkeys are best adapted to run on upward inclines of about 16°. The utilization of diagonal sequence gaits on the upward inclines supports previous suggestions that the preference for these gaits in primates is associated with an evolutionary increase in climbing behaviors.