Robert B. Eckhardt

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.

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

Significance The population that has become known as Homo floresiensis has been described as “the most extreme human ever discovered.” Specimen LB1 from Liang Bua Cave is unusual, but craniofacial and postcranial characteristics originally said to be diagnostic of the new species are not evident in the other more fragmentary skeletons in the sample that resemble other recent small-bodied human populations in the region (including the Andaman Islands, Palau, and Flores itself). Here we demonstrate that the facial asymmetry, small endocranial volume, brachycephaly, disproportionately short femora, flat feet, and numerous other characteristics of LB1 are highly diagnostic of Down syndrome, one of the most commonly occurring developmental disorders in humans and also documented in related hominoids such as chimpanzees and orangutans. 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.

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

Significance The taxon “Homo floresiensis” was termed “the most important find in human evolution for 100 years.” The name was invented for several fragmentary skeletons found on one Indonesian island, all less than 100,000 y old (some as recent as 12,000 y), all coeval with only Homo sapiens existing everywhere else in the world. Defining taxonomic features appear in just a single specimen, LB1, which has the only known skull and femora. Key features of 380 mL and 1.06 m are shown here to be underestimates, supportable as species-defining only by overlooking asymmetry and disproportion that are general signs of abnormal development. Logically, patent isolated individual abnormality obviates new species status even without diagnosis of a particular syndrome. 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.

LB1 from Liang Bua, Flores: Craniofacial asymmetry confirmed, plagiocephaly diagnosis dubious

We are simultaneously pleased and puzzled by the paper of Kaifu et al. (2009) on asymmetry in the LB1 craniofacial skeleton. Satisfaction arises from their detailed confirmation of our findings (Jacob et al., 2006), particularly since abnormal asymmetry in LB1 previously had been denied, discounted, or attributed to extraneous causes such as taphonomy, now disproved. The first point of perplexity arises in their abstract: ‘‘One of the proposed pathological indicators that still remains untested is asymmetric distortion in the skull of LB1’’ (Jacob et al., 2006). We assume that the authors meant ‘‘unconfirmed,’’ since Jacob et al. proposed asymmetry as an indicator of developmental abnormality and provided quantitative criteria. Our results showed that LB1 exceeded the extent of asymmetry in published standards (see Jacob et al., references 47–57); therefore, the null hypothesis of a normal degree of asymmetry was rejected. These reference standards and procedures antedate the discovery of LB1, so that their results correspond effectively to ‘‘blinded’’ procedures used in biomedical research. Confirmation of craniofacial asymmetry by Kaifu et al. after these findings had been questioned by others raises many uncertainties about symmetry versus asymmetry, normal vs. abnormal, and the procedures and standards of replication brought to bear in paleoanthropological hypothesis testing. These are very large questions that cannot be dealt with in the scope of a brief comment, but which we will treat more fully elsewhere. Here we limit ourselves to points raised by previous studies. Falk et al. (2009) disputed our finding of asymmetry ‘‘by electronically bisecting and mirror imaging the two halves of LB1’s entire skull [their emphasis] along its midline, using the 3DCT data from the original LB1 specimen,’’ and concluded ‘‘Our results suggest an unremarkable and nonpathological degree of asymmetry in LB1’s face, contrary to Jacob et al. (2006).’’ Their test of our work was not a close replication, since we provided not only the 2D mirror-images reproduced by Falk et al., but also replicable measurements from the midline to various precisely located landmarks. This is a standard clinical approach (Peck and Peck, 1970). Cohen (1995) notes: ‘‘With respect to the normal face, subtle degrees of asymmetry become particularly evident when properly oriented frontal photographs are divided along the median plane and reprocessed, each side being paired with its mirror image, yielding two slightly different faces.’’ Precision is important because differences of a few percent distinguish normal from abnormal asymmetry. Although not used by Falk et al., these methods are adaptable to CT scans (Netherway et al., 2006). Our photograph showing that the palatal midline is rotated 48 to 58 from the midsagittal plane (confirmed to within 18 by Kaifu et al.) was ignored. We intentionally were conservative in our reported values, anticipating that our findings would be disputed. Moreover, Figure 5 in Falk et al. omits the mandible of LB1. Although Kaifu et al. differ from Henneberg and Schofield (2008) in postulated causes, both sources accept that the lower dentition shows an asymmetric wear pattern due to some structurally related masticatory functional abnormality. Consequently, omitting the mandible under represents asymmetry. The 3DCT views in Falk et al. do not have sufficient resolution to show the anatomical detail that is present in our photographs. This lack of detail affects ability to locate virtually all of our measured points (chiefly foramina), precluding any effective quantitative comparison. Since Falk et al. have supplied no quantitative data on asymmetry of their own, their conclusion that the asymmetry of LB1 is ‘‘unremarkable and nonpathological’’ is unconvincing. That the two studies (Falk et al. and Jacob et al.) produce such different results is puzzling. Resolution of this apparent contradiction follows from realization that the findings reported by Falk et al. differ not only from measurements on photographs by Jacob et al., but also from the more directly comparable CT scans of Kaifu et al., who also aligned the mandible to produce a CT scan of the entire LB1 skull. Further, our data on asymmetry in the mandible cannot be affected materially by occlusal orientation, since they comprise measurements from the midline bilaterally to the mental foramina; they would remain unchanged even if the mandible were dissociated from the cranium. The assessment of asymmetry by Baab and McNulty (2009) also is questionable on numerous grounds, similar to those for Falk et al. Their experimental protocol was more extensive and quantified; nonetheless, they, too ignored LB1’s palatal rotation, and also introduced other

Polymorphisms Past and Present

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.

Intercellular competition and levels of development: The plasticity of inevitability

Nelson and Masel (1) present a general mathematical model that describes effects of somatic cell changes on aging bounded by juxtaposed loss of cellular vigor and uncontrolled cell growth. The formulation reflects observations on a wide range of multicellular organisms, from Caenorhabditis elegans to Homo sapiens , incorporating the Picard–Lindelof and Frobenius theorems, and using the Price equation to describe general effects of intercellular competition over organismal lifespan. The authors propose further comparisons: across taxa, among individuals of the same population, among tissues of the same individual, and across developmental time. Here we document parallel patterns bounded by vigor vs. proliferation developmentally mediated above intercellular levels. Our constructive perspective includes and extends research (2) on a unique human subpopulation defined by the common developmental genetic signature of Down syndrome (DS), trisomy-21. Phenotypically, DS … [↵][1]1To whom correspondence should be addressed. Email: eyl{at}psu.edu. [1]: #xref-corresp-1-1

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

Flawed arguments (1) ignoring our foundational paper (2) and disparaging “another pathology-based alternative” fail to support an invalidly invented hominin species.

Earliest Known Hominin Calcar Femorale in Orrorin tugenensis Provides Further Internal Anatomical Evidence for Origin of Human Bipedal Locomotion: CALCAR FEMORALE IN orrorin tugenensis

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.