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, 5 (9), e13018

Post-cranial Skeletons of Hypothyroid Cretins Show a Similar Anatomical Mosaic as Homo Floresiensis

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Post-cranial Skeletons of Hypothyroid Cretins Show a Similar Anatomical Mosaic as Homo Floresiensis

Charles Oxnard et al. PLoS One.

Abstract

Human remains, some as recent as 15 thousand years, from Liang Bua (LB) on the Indonesian island of Flores have been attributed to a new species, Homo floresiensis. The definition includes a mosaic of features, some like modern humans (hence derived: genus Homo), some like modern apes and australopithecines (hence primitive: not species sapiens), and some unique (hence new species: floresiensis). Conversely, because only modern humans (H. sapiens) are known in this region in the last 40 thousand years, these individuals have also been suggested to be genetic human dwarfs. Such dwarfs resemble small humans and do not show the mosaic combination of the most complete individuals, LB1 and LB6, so this idea has been largely dismissed. We have previously shown that some features of the cranium of hypothyroid cretins are like those of LB1. Here we examine cretin postcrania to see if they show anatomical mosaics like H. floresiensis. We find that hypothyroid cretins share at least 10 postcranial features with Homo floresiensis and unaffected humans not found in apes (or australopithecines when materials permit). They share with H. floresiensis, modern apes and australopithecines at least 11 postcranial features not found in unaffected humans. They share with H. floresiensis, at least 8 features not found in apes, australopithecines or unaffected humans. Sixteen features can be rendered metrically and multivariate analyses demonstrate that H. floresiensis co-locates with cretins, both being markedly separate from humans and chimpanzees (P<0.001: from analysis of similarity (ANOSIM) over all variables, ANOSIM, global R>0.999). We therefore conclude that LB1 and LB6, at least, are, most likely, endemic cretins from a population of unaffected Homo sapiens. This is consistent with recent hypothyroid endemic cretinism throughout Indonesia, including the nearby island of Bali.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Intrinsic foot proportions in cretins and Homo floresiensis as published in with data from 3 cretins (frame A) and four cretins and 2 Pan troglodytes (frame B) added.
A. Length of proximal phalanx relative to length of metatarsal for digit II is plotted against similar ratio for digit V. After ref. with cretin data added from Basle cretins. B. Ratio of metatarsal I length to tarsal length is plotted against the ratio of metatarsal II length to tarsal length. After ref. with cretin data from Basle and two chimpanzees (Pan troglodytes) added, and with the same definition of tarsal length, that is from the back of the talus forward not, as usually, from the posterior limit of the calcaneus.
Figure 2
Figure 2. Multivariate analyses of quantitative features of Homo floresiensis in relation to cretins, unaffected humans and chimpanzees.
Individuals are represented for each specimen by the coloured symbols above: H. floresiensis, young adult cretins, older cretins, H. sapiens, and P. troglodytes. Vectors are shown for each variable, abbreviated as in Tables 4, 5. The direction of each vector indicates the association with each axis and the length indicates the strength of the association. A. Principal Components Analysis (PCA) of all variables (16, from Tables 4, 5), 13 individuals, including 1 young adult cretin, 2 older cretins. PC1 and PC2 together explain 85.8% of variability. Two pairs of nearly coincident vectors (ppII/mtII, ppV/mtV and femur W/L, foot/leg) have similar directions and lengths. Three groups are clearly defined in 2 dimensions and confirmed over all dimensions (ANOSIM global R>0.999, P<.001). The group of LB and cretins is separate from H. sapiens (ANOSIM R>0.999, P<0.01) and Pan (R>0.999, P = 0.03). B. Multi-Dimensional Scaling (MDS) with individuals and variables as in a). Two Dimensional stress was 0.01 indicating that the plotted values give a very good indication of the rank Euclidean distance between individuals.
Figure 3
Figure 3. Additional multivariate analyses of quantitative features of Homo floresiensis in relation to cretins, unaffected humans and chimpanzees.
A. PCA using 14 variables and 14 individuals, as in a) but with 2 young adult cretins. PC1 and PC2 together explain 85.3% of variability. Three groups are clearly defined (ANOSIM global R>0.999, P<.001). The group of LB and cretins is separate from H. sapiens (ANOSIM R>0.999, P<0.01) and Pan (ANOSIM R>0.999, P<0.01). B. PCA using 9 variables, and 15 individuals, as in b) with additional 40 year old cretin. PC1 and PC2 together explain 79.9% of variability. ANOSIM global R = 0.949, P<.001. Group of LB and cretins is separate from H. sapiens (ANOSIM R = 0.843, P<0.01) and Pan (ANOSIM R>0.999, P<0.01).

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