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Biomedical subjects

R B Eckhardt

Publications and source records attributed to R B Eckhardt.

At least 19 recordsLinked to original sources
PubMed2006

Pygmoid Australomelanesian Homo sapiens skeletal remains from Liang Bua, Flores: population affinities and pathological abnormalities.

Liang Bua 1 (LB1) exhibits marked craniofacial and postcranial asymmetries and other indicators of abnormal growth and development. Anomalies aside, 140 cranial features place LB1 within modern human ranges of variation, resembling Australomelanesian populations. Mandibular and dental features of LB1 and LB6/1 either show no substantial deviation from modern Homo sapiens or share features (receding chins and rotated premolars) with Rampasasa pygmies now living near Liang Bua Cave. We propose that LB1 is drawn from an earlier pygmy H. sapiens population but individually shows signs of a developmental abnormality, including microcephaly. Additional mandibular and postcranial remains from the site share small body size but not microcephaly.

Bicuspid↗
PubMed2006

Superquadric modeling of cranial and cerebral shape and asymmetry.

A new method for quantifying cranial and cerebral shape and asymmetry fits symmetric superquadric geometric models to three-dimensional coordinate measurements. Asymmetry is quantified as radial residuals of the surface data points from their best-fit superquadric models. Twenty human crania, 10 magnetic resonance imaging (MRI) exocranial surfaces, and 10 corresponding MRI cerebral surfaces as well as two infant head casts were digitized and modeled using superquadrics. Superquadric parameters have simple geometric interpretation, are very reproducible, and demonstrated statistically significant differences between crania of Amerindian ancestry and MRI exocranial surfaces of European ancestry used in this study. Superquadric models demonstrated strong congruence between MRI exocranial and cerebral surfaces. Typical asymmetry was 1-5 mm. Lastly, polar contour plots of radial residuals for head casts before and after orthotic cranioplasty demonstrated the efficacy of using superquadrics to quantify positional plagiocephaly and synostosis of infant crania.

American Indian or Alaska Native↗
PubMed2004

External and internal morphology of the BAR 1002'00 Orrorin tugenensis femur.

Late Miocene fossils from the Lukeino Formation in Kenya's Tugen Hills are assigned to Orrorin tugenensis. Of 20 fossils recovered there to date, 3 are proximal femurs. One of these, BAR 1002'00, preserves an intact head connected to the proximal shaft by an elongated neck. Although this fossil is comparable in size to Pan troglodytes, computerized tomography scans of the neck-shaft junction of BAR 1002'00 reveal that the cortex is markedly thinner superiorly than inferiorly, differing from the approximately equal cortical thicknesses observed in extant African apes, approaching the condition in later hominids, and indicating that O. tugenensis was bipedal.

Animals↗
PubMed2001

Genetic research and nutritional individuality.

Recent genetic research builds on a base established over the last century by physicians and nutritional scientists, who introduced the concept of biochemical individuality and documented its significance for understanding a wide variety of problems in human health. Current comparative genomic investigations on a variety of organisms (Haemophilus influenzae, Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens) have established the existence of numerous orthologs (proteins in different organisms that show significant sequence similarities over 80% of their lengths), suggesting significant conservation of structure and probably some of function as well. At the same time, molecular comparisons among individuals within our own species show the existence of abundant molecular variants, many of which have been shown to have functional significance in nutritional and related metabolic contexts. The combination of biochemical individuality and known functional utilities of allelic variants should converge to create a situation in which nutritional optima can be specified as part of comprehensive lifestyle prescriptions tailored to the needs of each person.

Animals↗
PubMed1994

Ape family tree.

Explore the source record for details and available documents.

Animals↗
PubMed1992

Apes and apomorphies: the anterior nasal spine as a projection of cladistic conceptions.

Projections, tubercles, or spines of bone at the anterior margin of the piriform aperture occur in widely varying forms among catarrhine primates. This paper describes, illustrates, and tabulates the frequencies of such structures by age and sex in a large collection of Pan troglodytes verus skulls. In the overall sample of 263 skulls where the region could be observed, these protuberances of bone occur bilaterally in 10.7% of specimens and unilaterally in an additional 3.4%. They increase in frequency with age to a high of 16.9% in adult and older animals. Among adult specimens, these projections of bone in the anterior nasal region are present more commonly in females than in males. In a comparative context, variants on this structure in nonhuman primates, some of them documented previously, should help to counter the cladistic conception that the anterior nasal spine is an apomorphic or evolutionary novel morphological structure in hominids.

Age Factors↗
PubMed1991

Hominid brain evolution: two conceptions of science.

This paper re-examines the repeatedly-offered hypothesis (Fialkowski 1978, 1986, 1987, 1988) that hominid brain expansion was largely a side effect of evolutionary response to increased heat stress under conditions of primitive hunting, and resulted in a preadaptation to enhanced cognitive abilities. Fialkowski's hypothesis, previously shown to be based on data that are seriously inaccurate, continues to be presented in a manner that precludes testing. Consequently, however interesting these ideas may be, they are beyond the conventional domain of anthropology as a legitimate subdiscipline of modern science.

Adaptation, Biological↗
PubMed1990

Morphological variation in the nasal region of extant and fossil hominids.

We describe here the mid-facial region of a skull of anatomically modern Homo sapiens (FAI 3/2/1) that exhibits upwardly divergent nasal bones. In previous literature, that pattern has been described as a diagnostic character state for the robust early hominid taxon Paranthropus. This specimen supports our viewpoint that nasal region morphology varies extensively within and between living hominoid primate taxa, in patterns that provide a basis for understanding how microevolutionary variation serves as the basis for macroevolutionary transformations.

Animals↗
PubMed1989

Evolutionary morphology of human skeletal characteristics.

Human skeletal morphology has been a central focus of physical anthropology since the origin of the discipline about a century ago. Over that period skeletally-related characteristics, continuous and discontinuous, have been studied extensively in present and past populations. Through time our awareness of the interactions between the genetic and environmental influences reflected in skeletally-related phenotypes has become increasingly detailed and sophisticated. This paper reviews our growing knowledge of the genetic basis of human skeletal morphology, with particular emphasis on the significance of this information for the reconstruction of relationships among populations distributed broadly in space and time.

Anthropology, Physical↗
PubMed1987

Was plio-pleistocene hominid brain expansion a pleiotropic effect of adaptation to heat stress?

This paper examines the hypothesis (Fiałkowski 1978, 1986) that hominid brain expansion was largely a side effect of an evolutionary response to increased heat stress under conditions of primitive hunting, with reduction in reliability of brain components due to a rise in temperature having been offset by increases in the number of cerebral sub-units and interconnections among them. Fiałkowski's hypothesis is shown here to be based on measurements that are seriously inaccurate, and the explanatory mechanism to be contradicted by existing data on response to heat stress by smaller-brained nonhuman primates.

Animals↗
PubMed1975

The relative body weights of Bornean and Sumatran orangutans.

Although original field data suggested that the average Bornean orangutan weighed twice as much as the Sumatran ones, this is shown to be an error. The only statistically significant difference in weight is between males and females, regardless of geographical area or data source.

Analysis of Variance↗