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M W Marzke

Publications and source records attributed to M W Marzke.

18 recordsLinked to original sources
PubMed2003

Comparative morphology of the pollical distal phalanx.

Functional analysis of human pollical distal phalangeal (PDP) morphology is undertaken to establish a basis for the assessment of fossil hominid PDP morphology. Features that contribute to the effectiveness of grips involving the distal thumb and finger pulp areas include: 1) distal thumb interphalangeal joint morphology, facilitating PDP conjunct pronation with flexion; 2) differentiation of a proximal, mobile pulp region from a distal, stable pulp region, providing for firm precision pinch grips and precision handling of objects; and 3) asymmetric attachment of the flexor pollicis longus (FPL) tendon fibers, favoring PDP conjunct pronation. A proportionately larger size of the ulnar vs. radial ungual spine suggests differential loading intensity of the ulnar side of the proximal ungual pulp and supporting nail bed. Stresses at the distal interphalangeal joint are indicated by the presence of a sesamoid bone within the volar (palmar) plate, which also increases the length of the flexor pollicis longus tendon moment arm. Dissections of specimens from six nonhuman primate genera indicate that these human features are shared variably with individuals in other species, although the full pattern of features appears to be distinctively human. Humans share variably with these other species all metric relationships examined here. The new data identify a need to systematically review long-standing assumptions regarding the range of precision and power manipulative capabilities that might reasonably be inferred from morphology of the distal phalangeal tuberosity and from the FPL tendon insertion site on the PDP.

Animals↗
PubMed2003

Functional capabilities of modern and fossil hominid hands: three-dimensional analysis of trapezia.

Three-dimensional (3D) trapezium models from Homo sapiens, Gorilla gorilla, Pan troglodytes, Australopithecus afarensis (A.L.333-80), and Homo habilis (O.H.7-NNQ) were acquired through laser digitizing. Least-square planes were generated for each articular surface, and the angles between the planes were compared. Each extant species displays an overall pattern that distinguishes it from the others. The observed angles in G. gorilla and P. troglodytes are more similar to one other than either is to H. sapiens. Our results, obtained from using new 3D modeling and analytical tools, raise interesting questions about the functional capabilities of the fossil trapezia. Multivariate statistical analyses indicate that A.L.333-80 is morphologically more similar to that of modern humans, whereas the O.H.7 trapezium is more similar to that of the gorilla. Significant differences between A.L.333-80 and the extant species occur, but some similarities to humans suggest the ability to form the distinctively human forceful pad-to-side and three-jaw chuck grips. Some key morphological differences from humans highlighted and quantified by our research suggest limitations in the functional capabilities of the O.H.7 trapezium, particularly in those that facilitate pronation at the base of the second metacarpal. If the O.H.7 trapezium represents part of the hand responsible for manufacturing and using the stone tools found at Olduvai, our results suggest that the hand manipulated the stones in a way for which we have no modern analog. Alternative considerations are that the O.H.7 trapezium is not representative of other trapezia from its species (i.e., N=1), or that it represents another primate or hominid species.

Animals↗
PubMed2000

Evolution of the human hand: approaches to acquiring, analysing and interpreting the anatomical evidence.

The discovery of fossil hand bones from an early human ancestor at Olduvai Gorge in 1960, at the same level as primitive stone tools, generated a debate about the role of tools in the evolution of the human hand that has raged to the present day. Could the Olduvai hand have made the tools? Did the human hand evolve as an adaptation to tool making and tool use? The debate has been fueled by anatomical studies comparing living and fossil human and nonhuman primate hands, and by experimental observations. These have assessed the relative abilities of apes and humans to manufacture the Oldowan tools, but consensus has been hampered by disagreements about how to translate experimental data from living species into quantitative models for predicting the performance of fossil hands. Such models are now beginning to take shape as new techniques are applied to the capture, management and analysis of data on kinetic and kinematic variables ranging from hand joint structure, muscle mechanics, and the distribution and density of bone to joint movements and muscle recruitment during manipulative behaviour. The systematic comparative studies are highlighting a functional complex of features in the human hand facilitating a distinctive repertoire of grips that are apparently more effective for stone tool making than grips characterising various nonhuman primate species. The new techniques are identifying skeletal variables whose form may provide clues to the potential of fossil hominid hands for one-handed firm precision grips and fine precision manoeuvering movements, both of which are essential for habitual and effective tool making and tool use.

Animals↗
PubMed1999

Chimpanzee thumb muscle cross sections, moment arms and potential torques, and comparisons with humans.

This study investigates the morphological basis of differences between humans and chimpanzees in the kinematical and dynamical parameters of the musculature of the thumb. It is partly intended to test an hypothesis that human thumb muscles can exert significantly greater torques, due to larger muscle cross-sectional areas or to longer tendon moment arms or to both. We focus on the estimation of the potentials of thumb muscles to exert torques about joint axes in a sample of eight chimpanzee cadaver hands. The potential torque of a muscle is estimated by taking the product of a muscle's physiological cross-sectional area (an estimator of force) with its dynamical moment arm (derived from the slope of tendon excursion versus joint angular displacement, obtained during passive movements of cadaver thumb joints). Comparison of our results with similar data obtained for humans at the same Mayo Clinic laboratory shows significant differences between humans and chimpanzees in potential torque of most thumb muscles, those of humans generally exhibiting larger values. The primary reason for the larger torques in humans is that their average moment arms are significantly longer, permitting greater torque for a given muscle size. An additional finding is that chimpanzees and humans differ in the direction of secondary thumb metacarpal movements elicited by contraction of some muscles, as shown by differences in moment arm signs for a given movement in the same muscle. The differences appear to be related to differences in the musculo-skeletal structures of the trapeziometacarpal joint.

Animals↗
PubMed1998

EMG study of hand muscle recruitment during hard hammer percussion manufacture of Oldowan tools.

The activity of 17 hand muscles was monitored by electromyography (EMG) in three subjects during hard hammer percussion manufacture of Oldowan tools. Two of the subjects were archaeologists experienced in the replication of prehistoric stone tools. Simultaneous videotapes recorded grips associated with the muscle activities. The purpose of the study was to identify the muscles most likely to have been strongly and repeatedly recruited by early hominids during stone tool-making. This information is fundamental to the identification of skeletal features that may reliably predict tool-making capabilities in early hominids. The muscles most frequently recruited at high force levels for strong precision pinch grips required to control the hammerstone and core are the intrinsic muscles of the fifth finger and the thumb/index finger regions. A productive search for skeletal evidence of habitual Oldowan tool-making behavior will therefore be in the regions of the hand stressed by these intrinsic muscles and in the joint configurations affecting the relative lengths of their moment arms.

Animals↗
PubMed1997

Precision grips, hand morphology, and tools.

This study asks whether there are discernable links between precision gripping, tool behaviors, and hand morphology in modern hominoids, which may guide functional interpretation of early hominid hand morphology. Findings from a three-pronged investigation answer this question in the affirmative, as follows: (1) Experimental manufacture of early prehistoric tools provides evidence of connections between distinctive human precision grips and effective tool making. (A connection is not found between the "fine" thumb/index finger pad precision grip and early tool making.) (2) Manipulative behavior studies of chimpanzees, hamadryas baboons, and human show that human precision grips are distinguished by the greater force with which objects may be secured by the thumb and fingers of one hand (precision pinching) and the ability to adjust the orientation of gripped objects through movements at joints distal to the wrist (precision handling). (3) Morphological studies reveal eight featured distinctive of modern humans which facilitate use of these grips. Among these features are substantially larger moment arms for intrinsic muscles that stabilize the proximal thumb joints. Examination of evidence for these reveals that three of the eight features occur in Australopithecus afarensis, but limited thumb mobility would have compromised tool making. Also, Olduvai hand morphology strongly suggests a capacity for stone tool making. However, functional and behavioral implications of Sterkfontein and Swartkrans hand morphology are less clear. At present, no single skeletal feature can be safely relied upon as an indicator of distinctively human capabilities for precision gripping or tool making in fossil hominids.

Adaptation, Biological↗
PubMed1996

Comparative analysis of weight gain, hand/wrist maturation, and dental emergence rates in chimpanzees aged 0-24 months from varying captive environments.

Variability during the first 2 years of growth and development is examined in captive chimpanzees. The mixed longitudinal study of 175 animals compares curves of weight, hand/wrist maturation, and dental emergence for groups within the sample which differ in sex, rearing circumstances (mother-reared versus hand-reared), and colony (Primate Foundation of Arizona, White Sands Research Center, and The University of Texas M.D. Anderson Cancer Center Department of Veterinary Sciences in Bastrop, Texas). Comparison of LOWESS fits of the curves, using a conservative jack-knife approach, reveals trends toward significant differences between colonies for weight (with 4 comparisons reaching significance) and between rearing groups for maturation (1 reaching significance). Results of a full versus reduced model approach show the same trends, for which significance is reached in a higher number of comparisons. The latter approach also indicates possible effects of sex and environmental differences on dental emergence rate. Difficulties with both approaches are discussed. It is concluded that the results are suggestive of significant sex and environmental effects on the variables monitored, justifying further analysis and continuation of the study. The study is significant in 1) providing norms specific to sex and rearing and colony environments with which individual colony animals may be compared in the assessment of their development and in 2) providing a standard, based upon data from a larger and more varied captive chimpanzee population than previously available, with which the dental emergence status and hand/wrist maturation of fossil apes and hominids may be compared.

Aging↗
PubMed1996

Bicompartmentalization of the radiocarpal joint.

Seven wrists are presented with a septum connecting the lunotriquetral interosseous ligament and triangular fibrocartilage, resulting in bicompartmentalization of the radiocarpal joint. In all of the 7 wrists, having no history of trauma, the septums were suspected to be of congenital origin. The histopathology of the septum in 1 cadaver wrist showed a fibrocartilaginous structure. Two types of radiocarpal joint bicompartmentalization were identified by arthrography. Type 1 (2 wrists) had a septum with normal (intact) lunotriquetral interosseous ligament, and type 2 (5 wrists) had a septum with a communicating defect of the lunotriquetral interosseous ligament. The septum is most likely a congenital malformation caused by a disturbance of the vacuolization of the mesenchymal mass between the forearm and carpus.

Adult↗
PubMed1994

Variability at the carpometacarpal and midcarpal joints involving the fourth metacarpal, hamate, and lunate in catarrhini.

Intraspecies variability is investigated in two regions of the wrist, for the purpose of determining whether patterns may be discerned in the variability that may be compared in the functional and phylogenetic analysis of living and fossil catarrhines. In the midcarpal joint region, two lunatohamate configuration patterns are found, and at the fourth carpometacarpal joint four types of configuration are identified. These two sites previously were reported to show almost continuous variability in humans, thus precluding comparison with other species. The different types of configuration in our study are delineated on the basis of their relation to differences in joint function. At the lunatohamate site there is a strong tendency in each species examined for one type to dominate in frequency. At the fourth carpometacarpal joint there is a tendency for one type or for two related types to predominate in each species. The chimpanzee sample exhibits the least variability of all species studied in joint configuration at the two sites. Australopithecus afarensis has a combination of joint types in these regions likely to be found today in only a small percentage of living Hominoidea. We conclude that patterns may be discerned at some joints in what was formerly considered to be a continuum of variation. Since these patterns (joint types) differ in their relative frequencies among living species, the frequency differences may be useful as a guide to the reconstruction of phylogenetic relationships and of potential wrist functions in fossil species.

Animals↗
PubMed1993

Implementation of digital stereo imaging for analysis of metaphyses and joints in skeletal collections.

The surface structure of the growing portion of bones, called the metaphysis, contains clues about the locomotor characteristics of various species. Present methods of capturing this anthropologically interesting surface are time-consuming and subject to human error. The research implements a digital stereo imaging technique for bone metaphyses and joints in skeletal collections. The corresponding points in two images collected from different angles are determined using an area-based correlation matching method. The depths of matched points are computed from the difference in location of the points in the two images. The paper presents a practical implementation of computer vision for anthropology using an 80286-based personal computer, a camera and a video digitiser. The stereo matching algorithm, a practical implementation of classical stereo imaging methods, takes less than 1 min and produces reasonable representations of mammal bones. The accuracy of the depth measurements ranged from 0.7 to 12 per cent for 45-150 cm object-camera distances. False matches occurred in approximately 6 per cent of the total matched points.

Animals↗
PubMed1992

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.

Adult↗
PubMed1992

Evolutionary development of the human thumb.

The bones and joints of the human thumb are a mosaic of primitive and unique features, reflecting stages in the evolution of the hand from a support element on the ground to a grasping structure in the trees and eventually to an organ dedicated entirely to manipulation. The trapeziometacarpal saddle joint configuration and associated musculature are shared with most nonhuman primate species, whereas the broad distal phalanx with its specialized palmar pad is unique to humans. Most of the distinctive features of the modern human thumb can be explained by the requirements for a firm grip and tolerance of large stresses associated with the use and manufacture of stone tools, which contributed for several million years to the survival of human ancestors after they returned to the ground. Fossil remains indicate that early members of the human family, Hominidae, had short thumbs relative to the length of the fingers, which were not subject to the large stresses associated with modern human manipulative behavior. Later hominids had very flat trapeziometacarpal joints and large distal phalanges, indicating a capacity for opposition of the thumb to all four fingertips and for tolerance of large stresses. Pathologies involving thumb joints contribute to the understanding of the sequence of changes in thumb morphology in the fossil record.

Animals↗
PubMed1989

The use of magnetic resonance imaging for measuring segment inertial properties.

The purpose of the study was to determine whether valid measures of segment inertial properties can be generated from a series of cross-sectional tissue scans using magnetic resonance imaging (MRI). The cross-sectional images for eight baboon cadaver segments (four forearms, two upper arms, and two lower legs) were digitized to yield areas of muscle, bone, and fat tissues. These data, along with tissue density values, were used for calculations of segment volume (V), density (D), mass (M), center of mass location (CM), and moment of inertia (Icm) about a transverse axis through the segment center of mass. Criterion measures of these properties were obtained using standard experimental techniques. Close agreement was found between criterion and MRI values for mean segment CM (44.67 vs. 43.36% from proximal end, respectively) while mean segment D was the same (1.124 g.cm-3) for both methods. MRI procedures tended to overestimate segment V(595.3 vs. 633.4 cm3), M(720.0 vs. 769.9 g), and Icm (3.208 vs. 3.332 x 10(-3) kg.m2). It was concluded that MRI represents a promising technique for generating valid measures of segment inertial characteristics as well as other anatomical features.

Animals↗
PubMed1988

Gluteus maximus muscle function and the origin of hominid bipedality.

Bipedality not only frees the hands for tool use but also enhances tool use by allowing use of the trunk for leverage in applying force and thus imparting greater final velocity to tools. Since the weight and acceleration of the trunk and forelimbs on the hindlimbs must be counteracted by muscles such as m. gluteus maximus that control pelvic and trunk movements, it is suggested that the large size of the cranial portion of the human gluteus maximus muscle and its unique attachment to the dorsal ilium (which is apparent in the Makapan australopithecine ilium) may have contributed to the effectiveness with which trunk movement was exploited in early hominid foraging activities. To test this hypothesis, the cranial portions of both right and left muscles were investigated in six human subjects with electromyography during throwing, clubbing, digging, and lifting. The muscles were found to be significantly recruited when the trunk is used in throwing and clubbing, initiating rotation of the pelvis and braking it as trunk rotation ceases and the forelimb accelerates. They stabilize the pelvis during digging and exhibit marked and prolonged activity when the trunk is maintained in partial flexion during lifting of heavy objects.

Adult↗
PubMed1987

The third metacarpal styloid process in humans: origin and functions.

The development, mechanics, and pathology of the third carpometacarpal joint have been investigated in order to explain the unique presence in humans of a styloid process on the third metacarpal. Structure and functions of the joint are compared in a large series of Old World anthropoid hand skeletons, cadavers, and X-rays, and shown to differ in the three groups. Developmental anomalies reveal the source of the human styloid in a group of cells which fuse with the capitate in other Old World Anthropoidea. The absence of the process in Australopithecus afarensis and its presence in Neandertals suggest that an explanation for the evolution of the process may be sought in stresses on the hand in stone tool-use. Film analysis of stone tool-use shows that hammering and digging with hand-held stones direct forces on the palmar aspect of the metacarpal head. From a biomechanical analysis of these forces it may be seen that the styloid process prevents subluxation of the base. The effectiveness of the process in this function is reflected by the rarity of injury and arthritis in the region. Individuals lacking the process tend to undergo degeneration of bone at the joint. Since repetitive impulsive forces on joints are known to cause osteoarthritis, it is suggested that there may be a link between the increasing reliance of early hominids on manipulative behavior that stressed this region of the hand and the evolution of a structural pattern that protects the joint from these stresses.

Animals↗
PubMed1984

Evidence of hypertrophic pulmonary osteoarthropathy in a chimpanzee, Pan troglodytes.

Dissection of a chimpanzee has revealed the association of an intrathoracic disease (probably coccidioidomycosis) with periosteal lesions that are restricted almost entirely to the appendicular skeleton and are distributed with bilateral symmetry. These pathological conditions are compatible with a diagnosis of hypertrophic pulmonary osteoarthropathy.

Animals↗