Structural patterns of enamel in the superfamily Ceboidea

A fundamental enamel structure was found in the superfamily Ceboidea, and tentatively named the nonserial pattern, as distinguished from the multiserial and uniserial patterns. In the nonserial pattern, almost all rows of enamel prisms are straight to slightly curved from the enameldentin junction to the surface of the tooth, and are nearly uniformly oriented. Accordingly, Schreger's band is definitely lacking throughout the length and width of enamel. The interprismatic bundles between both adjacent rows are well developed. The nonserial pattern has so far been found to be limited to some genera of which the molars preserve rather primitive external features; i.e.,Saimiri, Callicebus, Aotus, Alouatta, Saguinus andLeontopithecus. On the other hand, the multiserial pattern is fairly common in many genera of the Ceboidea. The nonserial pattern, which corresponds to the pattern I described byBoyde (1964), is the most primitive, judging from its occurrence, structural simplicity and other factors. The multiserial and uniserial patterns are assumed to be independently evolved from the nonserial pattern.     

Metatarsal robusticity in primates and a few other plantigrade mammals

By using a new technique for determining relative metatarsal robusticity, the distribution of the 1+5 pattern (in which M5 is the second most robust metatarsal after M1) and 15 pattern (in which M5 is the least robust of all metatarsals) was established in primates and a few other plantigrade mammals. The first pattern is associated with a terrestrial and the second with an arboreal substrate. Robusticity formulae are not connected with specific locomotor patterns, but a total robusticity quotient is associated with these patterns and substrate preference as well. Changes in substrate preference are accompanied by changes of total robusticity, an increased number of permutations and ultimately a change of the robusticity pattern. Intermetatarsal robusticity gradients are related to the direction and intensity of muscular activity. A combined analysis of all factors can reveal a great deal of the locomotor history of a taxon.Also ofThe Institute of Applied Biology, New York.     

The cross-sectional geometry of the hand and foot bones of the hominoidea and its relationship to locomotor behavior

Cheiridia are valuable indicators of positional behavior, as they directly contact the substrate, but systematic comparison of the structural properties of both metacarpals and metatarsals has never been carried out. Differences in locomotor behavior among the great apes (knuckle-walking vs. quadrumanous climbing) can produce biomechanical differences that may be elucidated by the parallel study of cross-sectional characteristics of metacarpals and metatarsals. The aim of this work is to study the cross-sectional geometric properties of these bones and their correlation with locomotor behavior in large-bodied hominoids. The comparisons between bending moments of metacarpals and metatarsals of the same ray furnished interesting results. Metacarpals III and especially IV of the knuckle-walking African apes were relatively stronger than those of humans and orangutans, and metatarsal V of humans was relatively stronger than those of the great apes. Interestingly, the relative robusticity of the metacarpal IV of the quadrumanous orangutan was between that of the African apes and that of humans. The main conclusions of the study are: 1) cross-sectional dimensions of metacarpals and metatarsals are influenced by locomotor modes in great apes and humans; 2) interlimb comparisons of cross-sectional properties of metacarpals and metatarsals are good indicators of locomotor modes in great apes and humans; and 3) the results of this study are in accord with those of previous analyses of plantar pressure and morphofunctional traits of the same bones, and with behavioral studies. These results provide a data base from which it will be possible to compare the morphology of the fossils in order to gain insight into the locomotor repertoires of extinct taxa.     

Hand locomotor functions, body structure, and epidermal ridge patterns: preliminary study

The purpose of this study was to determine whether any relationships exist between hand locomotor functions and dermatoglyphic characteristics and body structure. The pilot sample consisted of 71 adult normal individuals (30 males and 41 females). The locomotor function tests included a power grip and two precision grips; dermatoglyphic features were represented by finger and palmar pattern intensities and ridge counts, and body structure by 35 head, face, trunk, and limb anthropometric measurements. Univariate and multivariate correlation analyses reveal that on average half of the variance in the locomotor hand-function tests can be accounted for by a set of body and/or dermatoglyphic variables in males; this contribution is appreciably lower in females. Body longitudinal measurements and some facial measures, such as jaw length, were found to be the main correlates of either a power grip or a simple thumb-index squeeze, especially in males; head and face measurements and the size and intensity of patterns on fingers 1 and 2 were the main correlates of more complex precision tests involving complicated manipulation of objects using the thumb and index finger. These preliminary results identify some previously unknown sources of variation in dermatoglyphic patterns and contribute to a better understanding of the evolutionary aspects of the relationships between specific functional and morphologic traits in humans.     

The human extensor digitorum profundus muscle with comments on the evolution of the primate hand

Forelimb dissections on 14 genera of anthropoids including humans and 17 cases of human aneuploids has revealed a high incidence of “atavistic” musculature (Barash et al., 1970;Aziz, 1981a) in the aneuploids. The phenotypic specificity of this aneuploid musculature clearly manifests developmental retardation and instability (Shapiro, 1983) revealing not only the likely course of embryonic myogenesis in chromosomally normal humans (Cihak, 1972, 1977) but also information relevant to ontogenetic and evolutionary changes. The extensor digitorum profundus proprius complex is particularly illustrative of these characteristics of aneuploid musculature. Our examination of the variation of this muscle complex in human aneuploids and between primate genera reveals how normal ontogeny may proceed, as well as the morphological basis for the evolutionary changes in hand structure and function amongst Primates. We also consider the phylogenetic and functional significance of changes in the extensor digitorum profundus proprius with reference to the divergent locomotory and manipulative capabilities and behavior of Primates.     

Functional anatomy of the hand of Australopithecus africanus

The Sterkfontein hand bones, attributed to Australopithecus africanus, were analysed to determine potential hand function of the power grip type of this species. The metacarpus is as stable as that of modern humans, as indicated by the depth of the groove on the base of metacarpal 2, the styloid process of metacarpal 3, the base articular surface areas, and the ligament markings on the bases of the metacarpals. The flexion and rotation of metacarpal 5 might have been less than that of modern humans, due to a more marked ventral articular lip on the base. The metacarpus acts as a lever, acting in various planes. The extensor carpi ulnaris and extensor carpi radialis longus muscles were probably better developed than in modern humans. The extensor carpi radialis brevis and flexor carpi radialis muscles would probably have been as well developed as in modern humans. None of the long tendons have a mechanical disadvantage as compared to modern humans. The metacarpals have a high robusticity index. The proximal phalanges show some midshaft swelling, slightly greater curvature than in modern humans, and some side to side bowing: pongid features. The fibrous flexor sheath markings are well developed, but resemble those of modern humans rather than those of the pongids. A single middle phalanx resembles that of modern humans, and has well developed ridges for insertion of the flexor digitorum superficialis muscle. The distal phalanx of the thumb has a well developed region for insertion of the flexor pollicis longus muscle, and has a mechanical advantage over modern humans for action of this muscle at the interphalangeal joint. The features indicate that the hand of A. africanus was well adapted to powerful hand use, as in hammering, striking, chopping, scraping, and gouging actions, as well as for throwing and climbing activities.     

Evolution of the power ("squeeze") grip and its morphological correlates in hominids.

The "squeeze" form of power grip is investigated for the purposes of clarifying the hand posture and activities associated with the grip, assessing the potential in chimpanzees for using the grip, and identifying morphological correlates of an effective power grip that may be recognized in fossil hominid species. Our approaches include: (1) the analysis of the human grip, focusing on both the hand posture involved and hand movements associated with use of the grip in hammering; (2) the analysis of similar chimpanzee grips and associated movements; (3) comparative functional analysis of regions in the hand exploited and stressed by the grip and its associated movements in humans; and (4) a review of the literature on the power grip and its morphological correlates. Results of the study indicate that humans use a squeeze form of power grip effectively to wield cylindrical tools forcefully as extensions of the forearm. Several morphological features occur in high frequency among humans which facilitate the grip and are consistent with the large internal and external forces associated with it in hammering and in other tool-using activities. Chimpanzee hand postures resembling this form of human power grip are not fully comparable and lack some of these morphological correlates that facilitate its use. The hand of Australopithecus afarensis does not appear to have been stressed by use of the grip, but there is some evidence for this type of stress in the metacarpals from Sterkfontein Member 4. Hands from Olduvai and Swartkrans do not provide sufficient evidence for assessment of power grip capabilities.     

Taxonomic separation ofKengyilia (Poaceae: Triticeae) in relation to nearest relatedRoegneria,Elymus, andAgropyron,based on some morphological characters

Based on 100 species representative of the four genera, we scored 290 herbarium specimens for a number of morphological characters. The data were subjected to canonical discriminant analysis using characters different from those in the identification key to these genera byBaum, Yen, andYang (1991). These characters collectively support the four groupsAgropyron, Kengyilia, Roegneria, andElymus as previously defined. The four groups are also supported by the linear discriminant function with an overall rate of 83% correct classification. Length of lemma awn was found to be an additional diagnostic character asAgropyron andKengyilia have lemma awns shorter than 5 mm, whereasRoegneria andElymus have longer lemma awns with very few exceptions. Length of glume awns is also a useful supplementary generic diagnostic.Agropyron andElymus have glume awns, whereas the majority of species ofKengyilia and more than half of the species ofRoegneria lack them. If a glume awn is present it is usually not longer than 1 mm.     

The skeletal correlates of behavioral modification in the laboratory mouse (Mus musculus)

The effects of behavioral modification on the skeletal morphology of the laboratory mouse (Mus musculus) are investigated. Climibing, with increrased prehensile use of the foot, is found to bring about significant changes in metatarsal and long bone morphology. Differences in metatarsal robusticity related to weight-bearing differences associated with different locomotor patterns are reported for a natural history setting for Peromyscus.     

Toward a realistic optoelectronic-based kinematic model of the hand: representing the transverse metacarpal arch reduces accessory rotations of the metacarpophalangeal joints

A kinematic model representing the versatility of the human hand is needed to evaluate biomechanical function and predict injury risk in the workplace. We improved upon an existing optoelectronic-based kinematic hand model with grouped metacarpals by defining segmented metacarpals and adding the trapeziometacarpal joint of the thumb. Eight participants performed three static postures (neutral pose, cylinder grip, cap grip) to evaluate kinematic performance of three different models, with one, two, and four metacarpal segment(s). Mean distal transverse metacarpal arch angles in the four-segment metacarpal model were between 22.0° ± 3.3° (neutral pose) and 32.1° ± 3.7° (cap grip). Representation of the metacarpals greatly influenced metacarpophalangeal joint rotations. Both the two- and four-segment metacarpal models displayed significantly lower metacarpophalangeal joint ‘supination’ angles (than the one-segment model) for the fourth and fifth fingers. However, the largest reductions were for the four- versus one-segment models, with mean differences ranging from 9.3° (neutral pose) to 17.0° (cap grip) for the fourth finger and 16.3° (neutral pose) to 33.0° (cylinder grip) for the fifth finger. MCP joint abduction/adduction angles of the fourth and fifth fingers also decreased with segmentation of the metacarpals, although the lowest magnitudes generally occurred in the four-segment model. Overall, the four-segment metacarpal model produced the lowest accessory rotations in non-dominant axes, and best matched previous radiological studies that found MCP joint pronation/supination angles were typically less than 10°. The four-segment metacarpal model, with improved anatomic fidelity, will better serve future studies of detailed actions of the hand in clinical or work applications.     

Taxonomy and phylogeny of the tribePlucheeae (Asteraceae)

The tribePlucheeae (Benth.)A. Anderb., has been analysed cladistically by means of a computerized parsimony program (Hennig 86), using theArctotideae as outgroup. The results of the analysis are presented in a consensus tree and one cladogram. Four major monophyletic subgroups can be recognized: TheColeocoma group (3 genera), thePterocaulon group (3 genera), theLaggera group (6 genera), and thePluchea group (12 genera). All recognized genera are described and most genera are supplied with taxonomical notes including comments on their taxonomic status. Genera such asBlumea, Pluchea, andEpaltes are demonstrated to be unnatural assemblages.Monarrhenus andTessaria are both closely related to thePluchea complex. The old generic nameLitogyne Harv. has been taken up for one species ofEpaltes, the genusRhodogeron is reduced to a synonym ofSachsia, and the following new combinations are made;Litogyne gariepina (DC.)A. Anderb., andSachsia coronopifolia (Griseb.)A. Anderb.     

A discussion of the classesChlamydophyceae andChlorophyceae and their subordinate taxa

The diagnostic characters alleged byEttl (1981) andEttl &Komarek (1982) to distinguish the ClassesChlamydophyceae andChlorophyceae are discussed. The recognition of these classes ignores ultrastructural evidence of the close phylogenetic relationships of their members and produces an artificial redistribution of orders, families, and genera that can only lead to confusion in the taxonomy of the green algae. Suggestions for a more natural classification are made.     

Precision grips in young chimpanzees

A precision grip, thumb-finger opposition, has been regarded as an uniquely human trait. Napier's conclusion that chimpanzees were incapable of precision grip was based on two subjects and prehension of a single object (i.e., a grape). The purpose of the present study was to specify grip type and hand use by 13 young chimpanzees to prehend three different-sized food objects. The subjects were laboratory raised (eight males and five females) and ranged in age from 27 to 58 months. An ethogram was devised that comprised 43 different grip types: ten configurations of precision grips were found, in addition to imprecise or inefficient grip types (nine types), thumb-to-finger opposition (10 types), power grips (two types), and a variety of other grips (12 types). Subjects most often prehended were very small-sized (5 mm × 5 mm × 3 mm) or small-sized (10 mm × 10 mm × 3 mm) food objects with precision and imprecise grips. An analysis of latency to prehend, i.e., efficiency, revealed (1) precision grips were equally efficient for all object sizes; (2) power grips were most efficient with the largest object (a grape); (3) with imprecise grips, the left hand was more efficient than the right with small objects, and with power grips the right hand was more efficient than the left for medium-sized objects. No population handedness was observed, but individual handedness was seen in nine subjects for some grip types and some object sizes. This study provides evidence that young chimpanzees preferentially use a true precision grip to prehend small and very small objects. © 1996 Wiley-Liss, Inc.     

Robusticity and osteoarthritis at the trapeziometacarpal joint in a Bronze Age population from Tell Abraq, United Arab Emirates

Osteoarthritis (OA) is a progressive disease of the joints and can cause pain, reduced range of motion and strength, and ultimately loss of function at affected joints. Osteoarthritis often occurs at sites where biomechanical stress is acutely severe or moderate but habitual over the course of a lifetime. Skeletal remains from an Umm an-Nar tomb at Tell Abraq, United Arab Emirates (ca. 2300 BC), were recovered and represented over 300 individuals of all ages. The remains were disarticulated, commingled, and mostly fragmented. An analysis of 650 well-preserved adult metacarpal and carpal bones, from the tomb's western chamber, revealed that over 53% of the trapeziometacarpal joint facets showed signs of OA varying from mild to severe. The first and second metacarpals and trapezium bones were sided and evaluated for OA at the trapeziometacarpal joint articulations. Osteoarthritis was detected on 53% of the first metacarpals, 40% of the second metacarpals, and 57% of the trapezium bones. All specimens appeared enlarged, and the first metacarpals were assessed for sexual identification and robusticity. Eighty-five percent of the bones were probable males, and more than 80% of them had a robusticity index of 60 or higher. A strong correlation was found between OA, sex, and robusticity. High levels of OA and robusticity at the thumb suggest that the people of Tell Abraq were habitually involved in biomechanically challenging work with their hands.     

An application of isoelectric focusing to non-human primates hair Keratin

This study is an investigation on the Keratin of hair coming from 51 non-human Primates belonging to 11 families and 37 different species, using isoelectric focusing on thin layer of polyacrylmide gel (0.5 mm) in pH range 2.5–7.0 followed by silver staining. Our results highlight that animals belonging to the same species have identical isoelectrophoretic patterns. It was proved forLemur fulvus, Macaca fascicularis, Cercopithecus aethiops, Gorilla gorilla. Instead, regarding different species belonging to the same genus, we can say that the pattern obtained was not always characteristic of the species to which the protein belonged. In fact, whereas some species of theCercopithecus, Macaca andPapio genus show significantly different patterns, other species ofCercopithecus, Macaca, Papio, Cebus andSaimiri show identifical patterns. On the other hand, patterns belonging to different genus nearly always showed more marked differences. As for man, by means of this technique, it is possible to show a high number of polypeptides in the 3–4 pH range for non-human Primates as well. Thus, species belonging to different families and genus can always be distinguished; on the other hand, it is not always possible for species of the same genus (e.g.Cebus, Papio).     

Fossil primate hands: A review and an evolutionary inquiry emphasizing early forms

The paleontological evidence pertaining to the evolution of the modern diversity in structure and function of primate hands is reviewed. A reconstructed digit ofPlesiadapis shows characters and functional capacities typical of an arboreal way of life. In euprimates, we describe the strepsirhine morphotype hand, characterized by a relatively high degree of pollical divergence, features of the ulnocarpal articulation that imply an enhanced capacity for ulnar deviation, and relatively long digits; this hand is specialized for grasping. Hand remains ofSmilodectes, Adapis and a Messel adapiform reveal a remarkable diversity in carpal structure achieved in these Eocene adapiforms, due to differing locomotor evolutionary pathways. The subfossil lemuriformsMegaladapis andPalaeopropithecus both show stereotyped (but different) grasping capabilities. The simiiform morphotype hand combines a relatively low degree of pollical divergence, features of the ulnocarpal articulation that imply a limited capacity for ulnar deviation, and relatively long metacarpals and short digits. This type of hand anatomy is mechanically well-suited to arboreal palmigrade quadrupedalism. The hands ofPliopithecus andMesopithecus are generally monkey-like.Oreopithecus' hand fits with its presumed suspensory habits. The hand ofProconsul suggests palmigrade quadrupedalism and climbing.Australopithecus afarensis' hand remains primarily a branch-grasping organ, with indications of enhanced manipulatory abilities.Homo habilis andParanthropus robustus illustrate two lines of increased tool-use abilities. The euprimate morphotype hand was elongated, had a short carpus and limited mobility, but the corresponding locomotor mode remains speculative. Considerations on hand evolution in some living primate groups are included in the final summary of hand evolution in primates.     

Biometrical characteristics of primate hands

The lenght proportions of the primate hands and their elements are analyzed in 43 extant genera and 6 fossil genera. The length of the hand in relation to the forelimb length does not characterize taxonomic groups, but rather locomotor modes, such as vertical-clinging-and-leaping, claw-climbing, and terrestrial quadrupedalism, as opposed to arboreal quadrupedalism. The relative lengths of the carpus, metacarpus, and digits appear mainly related to the phylogenetic history of the primates. Paraxony, instead of mesaxony, is the most frequent pattern of the simiiform hand, whereas hypermesaxony characterizes humans, hylobatids, and tarsiers. The proportions of the primitive euprimate hand are discussed in the light of the hand proportions of extant primates. Proportions drawn from hand remains ofMegaladapis edwardsi, Proconsul africanus, Mesopithecus pentelici, Notharctus, Adapis parisiensis, andPlesiadapis insignis are compared to those of extant primates, and discussed from both phylogenetical and functional points of view. To the memory of our colleague Jacques Lessertisseur.     

Carrying and hand-use patterns in Panamanian white-faced capuchins (Cebus capucinus)

The aim of this project was to examine the potential influence of postural regulation on capuchin hand-use patterns by focusing on tasks that involved the carrying of objects. Two months were spent on Barro Colorado Island, Panama, collecting data on ten white-faced capuchins (Cebus capucicus) (four adult males/six adult females). Over 215 contact hours were spent with the monkeys, and a total of 213 carries were recorded. No hand preference bias at the population level was found for the carry task; and no detectable hand-use patterns for carry were correlated with the weight of the object carried (except a right-hand bias for carrying medium-sized objects), the plane of the monkey's movement, its locomotor pattern, or its height above the ground. Therefore, the results of this study do not support the hypothesis that the need for postural regulation while carrying an object influences hand-use patterns in free-ranging capuchins. Our results are especially important because they are contrary to the results of the only other free-ranging capuchin laterality study conducted to date (Panger, 1998).     

Taxonomic studies of Choanephoraceae in India

Summary A taxonomic study of the members of the family Choanephoraceae was undertaken. Almost all the species of the family have been isolated from various sources in India. Two genera, viz.,Blakeslea andChoanephora have been recognized and a key to the genera has been given. The genusBlakeslea includes only one speciesB. trispora and the genusChoanephora five species. A key to the species has also been given. A new variety ofChoanephora circinans, viz.,C. circinans var.prolifera Mehrotra andMehrotra based on the proliferating vesicular apices of the sporangiophores has been described.     

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.