Publications by authors named "Robert B Eckhardt"

8 Publications

  • Page 1 of 1

Earliest Known Hominin Calcar Femorale in Orrorin tugenensis Provides Further Internal Anatomical Evidence for Origin of Human Bipedal Locomotion.

Anat Rec (Hoboken) 2018 11 19;301(11):1834-1839. Epub 2018 Oct 19.

Laboratory for the Comparative Study of Morphology, Mechanics and Molecules, Department of Kinesiology, Pennsylvania State University, State College, Pennsylvania, 16801.

The calcar femorale (CF), a plate of dense bone internal to the lesser trochanter, is visible on computed tomographic images of the 6 million-year-old femoral fragment BAR 1003'00 (from the taxon Orrorin tugenensis), among the oldest specimens relevant to reconstructing the evolution of human bipedal locomotion. A strongly expressed CF has been used previously as an indicator of bipedality. If true, then there should be a quantifiable difference in the CF among hominoids. Absolute and normalized CF lengths were measured from computed tomographic images at five anatomical locations along the proximal portion of BAR 1003'00 in addition to samples of nine H. sapiens and ten P. troglodytes femora. The span of the CF superiorly to inferiorly within the proximal femur was measured by counting the number of cross-sections on which the CF occurred. A Bayesian approach was used to classify the BAR 1003'00 sample based on normalized lengths. The P. troglodytes femora were more variable both in the occurrence of the trait and, where present, its span in the proximal femur. The H. sapiens sample exhibited CF lengths that were consistently larger at each location than the P. troglodytes in absolute terms, but the normalized lengths overlap substantially. The Bayesian posterior probability test classifies the CF of BAR 1003'00 with H. sapiens. The BAR 1003'00's calcar femorale has a strong anatomical similarity to the H. sapiens sample, supporting the conclusion that O. tugenensis is an early bipedal hominin. Anat Rec, 301:1834-1839, 2018. © 2018 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/ar.23939DOI Listing
November 2018

Intercellular competition and levels of development: The plasticity of inevitability.

Proc Natl Acad Sci U S A 2017 12 12;114(52):E11061-E11062. Epub 2017 Dec 12.

Adelaide Medical School, University of Adelaide, Adelaide, SA 5005, Australia.

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http://dx.doi.org/10.1073/pnas.1719479115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5748231PMC
December 2017

Reply to Westaway et al.: Mandibular misrepresentations fail to support the invalid species Homo floresiensis.

Proc Natl Acad Sci U S A 2015 Feb 6;112(7):E606. Epub 2015 Feb 6.

Kenneth J. Hsü Center for Integrated Hydrological Circuits Development, National Institutes of Earth Sciences, Beijing 100871, China.

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http://dx.doi.org/10.1073/pnas.1422176112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4343134PMC
February 2015

Evolved developmental homeostasis disturbed in LB1 from Flores, Indonesia, denotes Down syndrome and not diagnostic traits of the invalid species Homo floresiensis.

Proc Natl Acad Sci U S A 2014 Aug 4;111(33):11967-72. Epub 2014 Aug 4.

Kenneth J. Hsü Center for Integrated Hydrological Circuits Development, National Institutes of Earth Sciences, Beijing 100871, China

Human skeletons from Liang Bua Cave, Flores, Indonesia, are coeval with only Homo sapiens populations worldwide and no other previously known hominins. We report here for the first time to our knowledge the occipitofrontal circumference of specimen LB1. This datum makes it possible to link the 430-mL endocranial volume of LB1 reported by us previously, later confirmed independently by other investigators, not only with other human skeletal samples past and present but also with a large body of clinical data routinely collected on patients with developmental disorders. Our analyses show that the brain size of LB1 is in the range predicted for an individual with Down syndrome (DS) in a normal small-bodied population from the geographic region that includes Flores. Among additional diagnostic signs of DS and other skeletal dysplasiae are abnormally short femora combined with disproportionate flat feet. Liang Bua Cave femora, known only for LB1, match interlimb proportions for DS. Predictions based on corrected LB1 femur lengths show a stature normal for other H. sapiens populations in the region.
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http://dx.doi.org/10.1073/pnas.1407382111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4143021PMC
August 2014

Rare events in earth history include the LB1 human skeleton from Flores, Indonesia, as a developmental singularity, not a unique taxon.

Proc Natl Acad Sci U S A 2014 Aug 4;111(33):11961-6. Epub 2014 Aug 4.

Kenneth J. Hsü Center for Integrated Hydrological Circuits Development, National Institutes of Earth Sciences, Beijing 100871, China

The original centrally defining features of "Homo floresiensis" are based on bones represented only in the single specimen LB1. Initial published values of 380-mL endocranial volume and 1.06-m stature are markedly lower than later attempts to confirm them, and facial asymmetry originally unreported, then denied, has been established by our group and later confirmed independently. Of nearly 200 syndromes in which microcephaly is one sign, more than half include asymmetry as another sign and more than one-fourth also explicitly include short stature. The original diagnosis of the putative new species noted and dismissed just three developmental abnormalities. Subsequent independent attempts at diagnosis (Laron Syndrome, Majewski osteodysplastic primordial dwarfism type II, cretinism) have been hampered a priori by selectively restricted access to specimens, and disparaged a posteriori using data previously unpublished, without acknowledging that all of the independent diagnoses corroborate the patent abnormal singularity of LB1. In this report we establish in detail that even in the absence of a particular syndromic diagnosis, the originally defining features of LB1 do not establish either the uniqueness or normality necessary to meet the formal criteria for a type specimen of a new species. In a companion paper we present a new syndromic diagnosis for LB1.
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http://dx.doi.org/10.1073/pnas.1407385111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4143019PMC
August 2014

Polymorphisms past and present.

Hum Biol 2003 Aug;75(4):559-75

Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA.

Polymorphisms, particularly genetic variants of the red blood cell, have served as a major focus for the research of Frank B. Livingstone over the course of a long and productive career. Recent investigations confirm the value of key insights that he contributed to this area more than four decades ago. As Livingstone recognized, the same underlying evolutionary model that guides genetic studies in present populations also provides a productive framework for interpreting patterns of variation in the skeleton and dentition throughout past human evolution. Examples explored in detail here include polymorphisms in hominoid nasal bone shapes and fourth lower premolar roots. This work provides both empirical and theoretical contexts for investigating patterns of human variation over the last 6 to 8 million years.
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http://dx.doi.org/10.1353/hub.2003.0052DOI Listing
August 2003
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