owen lovejoy | Kent State University (original) (raw)

Papers by owen lovejoy

Densities of osteons and osteon fragments at the midshafts of the femur, tibia, fibula, humerus, ... more Densities of osteons and osteon fragments at the midshafts of the femur, tibia, fibula, humerus, radius, ulna and clavicle are examined in a sample of contemporary human males and females (n = 39; 23 female, 16 male), with comparative data derived from one specimen each of Gallus gallus and Felis silvestris catus. Results demonstrate that there are significant differences in mean complete and fragmentary osteon densities among bones and between the sexes. We suggest that these patterns are less a simple reflection of the so-called "Wolff's law," but instead represent not only remodeling in response to loading, but also underlying intrinsic developmental parameters specific to each bone. Given the diversity of locomotor patterns of the three species, and the resulting differences in loading environments of their limbs, this histomorphological pattern suggests that remodeling is an inherently complex phenomenon, subject to local intrinsic developmental factors in addition to mechanical loading.

American Journal of Physical Anthropology, 1982

Anatomical descriptions are presented for the bones of the lower limb recovered from the Hadar Fo... more Anatomical descriptions are presented for the bones of the lower limb recovered from the Hadar Formation during the 1974–1977 field seasons, inclusive.

Journal of Human Evolution, 1986

American Journal of Physical Anthropology, 1993

The multifactorial aging method has been shown to be a highly reliable method of skeletal aging b... more The multifactorial aging method has been shown to be a highly reliable method of skeletal aging because it incorporates age information from as many age indicators as are available for each skeleton (Lovejoy et al.; Am. J. Phys. Anthropol. 68:1–14, 1985). The present study was a blind test to assess its accuracy on a skeletal sample composed of 55 individuals with verified death certificates (Grant Collection, University of Toronto). Three authors (C. O. L., M. E. B., and K. F. R.), with no access to the death certificate ages, independently seriated and aged the sample using three to four criteria: auricular surface, pubic symphysis, and radiographs of the proximal femur and clavicle. Summary ages were then calculated for each individual in the sample.The authors' independent summary age estimates showed strong correlations with one another (r = 0.84–0.89). Multifactorial age estimates correlated better with real age than did those from any single indicator used. The mean error (averaging 8.7 years) for summary age was at least 1 year less than that for any single indicator. Average bias ranged from −0.7 (underage) to 1.4 (overage) years. These results indicate that utilization of several age indicators, weighted according to their reliability, helps control for variation in the changes that occur with age in any single morphological indicator. This method may therefore be considered one of the most accurate available for the determination of skeletal age-at-death, particularly for paleodemographic analysis. © 1993 Wiley-Liss, Inc.

American Journal of Physical Anthropology, 2002

MAK-VP-1/1, a proximal femur recovered from the Maka Sands (ca. 3.4 mya) of the Middle Awash, Eth... more MAK-VP-1/1, a proximal femur recovered from the Maka Sands (ca. 3.4 mya) of the Middle Awash, Ethiopia, and attributed to Australopithecus afarensis, is described in detail. It represents the oldest skeletal evidence of locomotion in this species, and is analyzed from a morphogenetic perspective. X-ray, CT, and metric data are evaluated, using a variety of methods including discriminant function. The specimen indicates that the hip joint of A. afarensis was remarkably like that of modern humans, and that the dramatic muscle allocation shifts which distinguish living humans and African apes were already present in a highly derived form in this species. Its anatomy provides no indication of any form of locomotion save habitual terrestrial bipedality, which very probably differed only trivially from that of modern humans. Am J Phys Anthropol 119:97–133, 2002. © 2002 Wiley-Liss, Inc.

Science, 1977

widest bandwidth system now in use. Since the signal-to-noise ratio for a wideband radio astronom... more widest bandwidth system now in use. Since the signal-to-noise ratio for a wideband radio astronomy signal varies as the square root of the bandwidth, this wider bandwidth results in a significant improvement. Much larger bandwidths are possible with existing technology.

American Journal of Physical Anthropology, 1985

Traditional methods of estimating skeletal age at death have relied solely on the pubic symphysea... more Traditional methods of estimating skeletal age at death have relied solely on the pubic symphyseal face or on this indicator combined with others in nonsystematic ways. A multifactorial method is presented that uses a principal components weighting of five indicators (pubic symphyseal face, auricular surface, radiographs of proximal femur, dental wear, and suture closure). This method has been tested by completely blind assessment of age in two samples from the Todd collection carefully screened for accuracy of stated age at death. Results show a marked superiority of the multifactorial method over any single indicator with respect to both bias and accuracy. This represents the first truly blind test of an age-at-death indicator or system, as the test populations were independent of the system(s) being tested, and the age, sex, and ethnogeographic origin of the individuals being assessed (as well as the compositions of the test samples with respect to these variables) were completely unknown until the tests were completed. Implications for paleodemography are discussed.

American Journal of Physical Anthropology, 1985

Modal patterns of occlusal attrition are presented for the Libben population based on a sample of... more Modal patterns of occlusal attrition are presented for the Libben population based on a sample of 332 adult dentitions. Maxillas and mandibles were reviewed independently by seriation prior to assessment of complete dentitions. The Spearman rank order coefficient for upper and lower dentitions was.96. Wear patterns are very similar to those reported by Murphy (1959a: Am. J. Phys. Anthropol. 17:167–178) for Australian aborigines. There were no significant sexual differences in wear rate. Dental wear is concluded to be a highly reliable and important indicator of adult age at death for skeletal populations if seriation procedures are employed.

American Journal of Physical Anthropology, 1985

All current standardized methods of age determination using the os pubis were tested by blind ass... more All current standardized methods of age determination using the os pubis were tested by blind assessment of a skeletal sample with documented ages (from the Todd collection; N = 96). No demographic data (sex, age, race, age composition) were known to the assessors prior to completion of the test. Results showed the Todd method to be more reliable than more recent component techniques and that all systems tended to underage. Therefore, modifications were made of the Todd system to eliminate this and other deficiencies, and a second test using a new sample was conducted (N = 109). The age distribution determined by the revised Todd method did not significantly differ from the actual age distribution of the second sample. Error due to race was nonsignificant. Biological stages of pubic metamorphosis are described and possible evolutionary specializations of the hominid symphysis are discussed. Revised standards for age determination are presented.

American Journal of Physical Anthropology, 1985

Determinations of sex by subjective assessment of the skulls from a skeletal series of known sex ... more Determinations of sex by subjective assessment of the skulls from a skeletal series of known sex were compared to fully independent assessments based on pelves of the same specimens. Within-sex correlations of cranial and pelvic morphologies measured on an android-gynecoid scale were smaller than expected. Subjective assessment by means of the skull compared favorably to that of the linear discriminant functions of Giles and Elliot; however, the direction of error was similar for both procedures. Of course, estimations based on the pelves were generally superior to both in terms of frequency and overall bias of error. The bias of sex estimation for paleodemographic purposes is contingent upon completeness of skeletal remains.

American Journal of Physical Anthropology, 1985

Visually seriated radiographs of the proximal femur, proximal humerus, clavicle, and calcaneus fr... more Visually seriated radiographs of the proximal femur, proximal humerus, clavicle, and calcaneus from 130 individuals from the Hamann-Todd collection were examined as indicators of skeletal age at death. The clavicle demonstrated the most consistent relationship to age in both sexes. The same radiographs were also seriated by size-normalized optical density as a means of establishing relative radiolucency. In this context, visual seriation proved superior. The four sites studied showed strong divergence in response to age. Since each was sampling bone response from the same individual, it is concluded that bone loss is highly site specific. This demonstrates the individual character of specific skeletal sites. Visual inspection of clavicular radiographs, seriated on a populational basis, provides age estimates that are comparable to anatomical age indicators and provides independent estimates of skeletal age when included in the summary age method (1985: Am. J. Phys. Anthropol. 68:1–14).

American Journal of Physical Anthropology, 1973

A biomechanical analysis of the pelvic and femoral samples available for Australopithecus is pres... more A biomechanical analysis of the pelvic and femoral samples available for Australopithecus is presented. No feature of these samples was found to distinguish their gait pattern from that of modern man or to differ in the two presently recognized allomorphs of Australopithecus. Morphological differences between Australopithecus and modern man appear to be the result of different degrees of encephalization rather than any difference in locomotor adaptation.

American Journal of Physical Anthropology, 1997

Contiguous high resolution computed tomography images were obtained at a 1.5 mm slice thickness p... more Contiguous high resolution computed tomography images were obtained at a 1.5 mm slice thickness perpendicular to the neck axis from the base of the femoral head to the trochanteric line in a sample of 10 specimens each of Homo sapiens, Pan troglodytes, and Gorilla gorilla, plus five specimens of Pan paniscus. Superior, inferior, anterior, and posterior cortical thicknesses were automatically measured directly from these digital images. Throughout the femoral neck H. sapiens displays thin superior cortical bone and inferior cortical bone that thickens distally. In marked contrast, cortical bone in the femoral neck of African apes is more uniformly thick in all directions, with even greater thickening of the superior cortical bone distally. Because the femoral neck acts as a cantilevered beam, its anchorage at the neck-shaft junction is subjected to the highest bending stresses and is the most biomechanically relevant region to inspect for response to strain. As evinced by A.L. 128-1, A.L. 211-1 and MAK-VP-1/1, Australopithecus afarensis is indistinguishable from H. sapiens, but markedly different from African apes in cortical bone distribution at the femoral neck-shaft junction. Cortical distribution in the African ape indicates much greater variation in loading conditions consistent with their more varied locomotor repertoire. Cortical distribution in hominids is a response to the more stereotypic loading pattern imposed by habitual bipedality, and thin superior cortex in A. afarensis confirms the absence of a significant arboreal component in its locomotor repertoire.

Proceedings of The National Academy of Sciences, 1999

The past two decades have greatly improved our knowledge of vertebrate skeletal morphogenesis. It... more The past two decades have greatly improved our knowledge of vertebrate skeletal morphogenesis. It is now clear that bony morphology lacks individual descriptive specification and instead results from an interplay between positional information assigned during early limb bud deployment and its "execution" by highly conserved cellular response programs of derived connective tissue cells (e.g., chondroblasts and osteoblasts). Selection must therefore act on positional information and its apportionment, rather than on more individuated aspects of presumptive adult morphology. We suggest a trait classification system that can help integrate these findings in both functional and phylogenetic examinations of fossil mammals and provide examples from the human fossil record.

American Journal of Physical Anthropology, 1971

The anatomy of the distal femoral fragments from Sterkfontein is reviewed, including its orthopae... more The anatomy of the distal femoral fragments from Sterkfontein is reviewed, including its orthopaedic and biomechanical implications with respect to locomotion pattern. Comparisons are made with other hominids and a number of quadrupedal primates. Items which are considered are the obliquity and robustness of the shaft, the anterior intercondylar groove, the intercondylar notch, and the contour of the medial and lateral articular surfaces. The distinctive hominid status of these specimens is shown by their extensive adaptation to bipedal locomotion. No feature is found which is not fully commensurate with completely bipedal locomotion; rather, their distinctive hominid character points to a need for a reanalysis of the gait pattern in these early Pleistocene hominids.

Scientific American, 1988

Science, 1981

Experiments on DNA hybridization in-dicate at least 98 percent identity in non-repeated DNA in ma... more Experiments on DNA hybridization in-dicate at least 98 percent identity in non-repeated DNA in manand chimpanzee, sufficient similarity to suggest the possi-biliyfa viable hybrid. These data con-firm studies by comparative anatomists who have emphasized the striking ana- ...

American Journal of Physical Anthropology, 1976

Traditional methods of bone analysis (both metric and topographic) are restricted to external cha... more Traditional methods of bone analysis (both metric and topographic) are restricted to external characters. Spacial distribution of material is, however, equally critical to an understanding of a bone's function. Dynamic testing to determine whole bone strength can only be performed on fresh specimens. Methods for the calculation of both bending and torsional strength of other specimens (such as preserved or fossil bones) are developed in this paper. In order to illustrate the methods, the functional significance of tibial shaft cross sectional variation is investigated.

Densities of osteons and osteon fragments at the midshafts of the femur, tibia, fibula, humerus, ... more Densities of osteons and osteon fragments at the midshafts of the femur, tibia, fibula, humerus, radius, ulna and clavicle are examined in a sample of contemporary human males and females (n = 39; 23 female, 16 male), with comparative data derived from one specimen each of Gallus gallus and Felis silvestris catus. Results demonstrate that there are significant differences in mean complete and fragmentary osteon densities among bones and between the sexes. We suggest that these patterns are less a simple reflection of the so-called "Wolff's law," but instead represent not only remodeling in response to loading, but also underlying intrinsic developmental parameters specific to each bone. Given the diversity of locomotor patterns of the three species, and the resulting differences in loading environments of their limbs, this histomorphological pattern suggests that remodeling is an inherently complex phenomenon, subject to local intrinsic developmental factors in addition to mechanical loading.

American Journal of Physical Anthropology, 1982

Anatomical descriptions are presented for the bones of the lower limb recovered from the Hadar Fo... more Anatomical descriptions are presented for the bones of the lower limb recovered from the Hadar Formation during the 1974–1977 field seasons, inclusive.

Journal of Human Evolution, 1986

American Journal of Physical Anthropology, 1993

The multifactorial aging method has been shown to be a highly reliable method of skeletal aging b... more The multifactorial aging method has been shown to be a highly reliable method of skeletal aging because it incorporates age information from as many age indicators as are available for each skeleton (Lovejoy et al.; Am. J. Phys. Anthropol. 68:1–14, 1985). The present study was a blind test to assess its accuracy on a skeletal sample composed of 55 individuals with verified death certificates (Grant Collection, University of Toronto). Three authors (C. O. L., M. E. B., and K. F. R.), with no access to the death certificate ages, independently seriated and aged the sample using three to four criteria: auricular surface, pubic symphysis, and radiographs of the proximal femur and clavicle. Summary ages were then calculated for each individual in the sample.The authors' independent summary age estimates showed strong correlations with one another (r = 0.84–0.89). Multifactorial age estimates correlated better with real age than did those from any single indicator used. The mean error (averaging 8.7 years) for summary age was at least 1 year less than that for any single indicator. Average bias ranged from −0.7 (underage) to 1.4 (overage) years. These results indicate that utilization of several age indicators, weighted according to their reliability, helps control for variation in the changes that occur with age in any single morphological indicator. This method may therefore be considered one of the most accurate available for the determination of skeletal age-at-death, particularly for paleodemographic analysis. © 1993 Wiley-Liss, Inc.

American Journal of Physical Anthropology, 2002

MAK-VP-1/1, a proximal femur recovered from the Maka Sands (ca. 3.4 mya) of the Middle Awash, Eth... more MAK-VP-1/1, a proximal femur recovered from the Maka Sands (ca. 3.4 mya) of the Middle Awash, Ethiopia, and attributed to Australopithecus afarensis, is described in detail. It represents the oldest skeletal evidence of locomotion in this species, and is analyzed from a morphogenetic perspective. X-ray, CT, and metric data are evaluated, using a variety of methods including discriminant function. The specimen indicates that the hip joint of A. afarensis was remarkably like that of modern humans, and that the dramatic muscle allocation shifts which distinguish living humans and African apes were already present in a highly derived form in this species. Its anatomy provides no indication of any form of locomotion save habitual terrestrial bipedality, which very probably differed only trivially from that of modern humans. Am J Phys Anthropol 119:97–133, 2002. © 2002 Wiley-Liss, Inc.

Science, 1977

widest bandwidth system now in use. Since the signal-to-noise ratio for a wideband radio astronom... more widest bandwidth system now in use. Since the signal-to-noise ratio for a wideband radio astronomy signal varies as the square root of the bandwidth, this wider bandwidth results in a significant improvement. Much larger bandwidths are possible with existing technology.

American Journal of Physical Anthropology, 1985

Traditional methods of estimating skeletal age at death have relied solely on the pubic symphysea... more Traditional methods of estimating skeletal age at death have relied solely on the pubic symphyseal face or on this indicator combined with others in nonsystematic ways. A multifactorial method is presented that uses a principal components weighting of five indicators (pubic symphyseal face, auricular surface, radiographs of proximal femur, dental wear, and suture closure). This method has been tested by completely blind assessment of age in two samples from the Todd collection carefully screened for accuracy of stated age at death. Results show a marked superiority of the multifactorial method over any single indicator with respect to both bias and accuracy. This represents the first truly blind test of an age-at-death indicator or system, as the test populations were independent of the system(s) being tested, and the age, sex, and ethnogeographic origin of the individuals being assessed (as well as the compositions of the test samples with respect to these variables) were completely unknown until the tests were completed. Implications for paleodemography are discussed.

American Journal of Physical Anthropology, 1985

Modal patterns of occlusal attrition are presented for the Libben population based on a sample of... more Modal patterns of occlusal attrition are presented for the Libben population based on a sample of 332 adult dentitions. Maxillas and mandibles were reviewed independently by seriation prior to assessment of complete dentitions. The Spearman rank order coefficient for upper and lower dentitions was.96. Wear patterns are very similar to those reported by Murphy (1959a: Am. J. Phys. Anthropol. 17:167–178) for Australian aborigines. There were no significant sexual differences in wear rate. Dental wear is concluded to be a highly reliable and important indicator of adult age at death for skeletal populations if seriation procedures are employed.

American Journal of Physical Anthropology, 1985

All current standardized methods of age determination using the os pubis were tested by blind ass... more All current standardized methods of age determination using the os pubis were tested by blind assessment of a skeletal sample with documented ages (from the Todd collection; N = 96). No demographic data (sex, age, race, age composition) were known to the assessors prior to completion of the test. Results showed the Todd method to be more reliable than more recent component techniques and that all systems tended to underage. Therefore, modifications were made of the Todd system to eliminate this and other deficiencies, and a second test using a new sample was conducted (N = 109). The age distribution determined by the revised Todd method did not significantly differ from the actual age distribution of the second sample. Error due to race was nonsignificant. Biological stages of pubic metamorphosis are described and possible evolutionary specializations of the hominid symphysis are discussed. Revised standards for age determination are presented.

American Journal of Physical Anthropology, 1985

Determinations of sex by subjective assessment of the skulls from a skeletal series of known sex ... more Determinations of sex by subjective assessment of the skulls from a skeletal series of known sex were compared to fully independent assessments based on pelves of the same specimens. Within-sex correlations of cranial and pelvic morphologies measured on an android-gynecoid scale were smaller than expected. Subjective assessment by means of the skull compared favorably to that of the linear discriminant functions of Giles and Elliot; however, the direction of error was similar for both procedures. Of course, estimations based on the pelves were generally superior to both in terms of frequency and overall bias of error. The bias of sex estimation for paleodemographic purposes is contingent upon completeness of skeletal remains.

American Journal of Physical Anthropology, 1985

Visually seriated radiographs of the proximal femur, proximal humerus, clavicle, and calcaneus fr... more Visually seriated radiographs of the proximal femur, proximal humerus, clavicle, and calcaneus from 130 individuals from the Hamann-Todd collection were examined as indicators of skeletal age at death. The clavicle demonstrated the most consistent relationship to age in both sexes. The same radiographs were also seriated by size-normalized optical density as a means of establishing relative radiolucency. In this context, visual seriation proved superior. The four sites studied showed strong divergence in response to age. Since each was sampling bone response from the same individual, it is concluded that bone loss is highly site specific. This demonstrates the individual character of specific skeletal sites. Visual inspection of clavicular radiographs, seriated on a populational basis, provides age estimates that are comparable to anatomical age indicators and provides independent estimates of skeletal age when included in the summary age method (1985: Am. J. Phys. Anthropol. 68:1–14).

American Journal of Physical Anthropology, 1973

A biomechanical analysis of the pelvic and femoral samples available for Australopithecus is pres... more A biomechanical analysis of the pelvic and femoral samples available for Australopithecus is presented. No feature of these samples was found to distinguish their gait pattern from that of modern man or to differ in the two presently recognized allomorphs of Australopithecus. Morphological differences between Australopithecus and modern man appear to be the result of different degrees of encephalization rather than any difference in locomotor adaptation.

American Journal of Physical Anthropology, 1997

Contiguous high resolution computed tomography images were obtained at a 1.5 mm slice thickness p... more Contiguous high resolution computed tomography images were obtained at a 1.5 mm slice thickness perpendicular to the neck axis from the base of the femoral head to the trochanteric line in a sample of 10 specimens each of Homo sapiens, Pan troglodytes, and Gorilla gorilla, plus five specimens of Pan paniscus. Superior, inferior, anterior, and posterior cortical thicknesses were automatically measured directly from these digital images. Throughout the femoral neck H. sapiens displays thin superior cortical bone and inferior cortical bone that thickens distally. In marked contrast, cortical bone in the femoral neck of African apes is more uniformly thick in all directions, with even greater thickening of the superior cortical bone distally. Because the femoral neck acts as a cantilevered beam, its anchorage at the neck-shaft junction is subjected to the highest bending stresses and is the most biomechanically relevant region to inspect for response to strain. As evinced by A.L. 128-1, A.L. 211-1 and MAK-VP-1/1, Australopithecus afarensis is indistinguishable from H. sapiens, but markedly different from African apes in cortical bone distribution at the femoral neck-shaft junction. Cortical distribution in the African ape indicates much greater variation in loading conditions consistent with their more varied locomotor repertoire. Cortical distribution in hominids is a response to the more stereotypic loading pattern imposed by habitual bipedality, and thin superior cortex in A. afarensis confirms the absence of a significant arboreal component in its locomotor repertoire.

Proceedings of The National Academy of Sciences, 1999

The past two decades have greatly improved our knowledge of vertebrate skeletal morphogenesis. It... more The past two decades have greatly improved our knowledge of vertebrate skeletal morphogenesis. It is now clear that bony morphology lacks individual descriptive specification and instead results from an interplay between positional information assigned during early limb bud deployment and its "execution" by highly conserved cellular response programs of derived connective tissue cells (e.g., chondroblasts and osteoblasts). Selection must therefore act on positional information and its apportionment, rather than on more individuated aspects of presumptive adult morphology. We suggest a trait classification system that can help integrate these findings in both functional and phylogenetic examinations of fossil mammals and provide examples from the human fossil record.

American Journal of Physical Anthropology, 1971

The anatomy of the distal femoral fragments from Sterkfontein is reviewed, including its orthopae... more The anatomy of the distal femoral fragments from Sterkfontein is reviewed, including its orthopaedic and biomechanical implications with respect to locomotion pattern. Comparisons are made with other hominids and a number of quadrupedal primates. Items which are considered are the obliquity and robustness of the shaft, the anterior intercondylar groove, the intercondylar notch, and the contour of the medial and lateral articular surfaces. The distinctive hominid status of these specimens is shown by their extensive adaptation to bipedal locomotion. No feature is found which is not fully commensurate with completely bipedal locomotion; rather, their distinctive hominid character points to a need for a reanalysis of the gait pattern in these early Pleistocene hominids.

Scientific American, 1988

Science, 1981

Experiments on DNA hybridization in-dicate at least 98 percent identity in non-repeated DNA in ma... more Experiments on DNA hybridization in-dicate at least 98 percent identity in non-repeated DNA in manand chimpanzee, sufficient similarity to suggest the possi-biliyfa viable hybrid. These data con-firm studies by comparative anatomists who have emphasized the striking ana- ...

American Journal of Physical Anthropology, 1976

Traditional methods of bone analysis (both metric and topographic) are restricted to external cha... more Traditional methods of bone analysis (both metric and topographic) are restricted to external characters. Spacial distribution of material is, however, equally critical to an understanding of a bone's function. Dynamic testing to determine whole bone strength can only be performed on fresh specimens. Methods for the calculation of both bending and torsional strength of other specimens (such as preserved or fossil bones) are developed in this paper. In order to illustrate the methods, the functional significance of tibial shaft cross sectional variation is investigated.