Prognathism and Facial Flatness

August 4, 2007

This study compares facial characteristics of 112 ancient, medieval and modern populations from around the world. The basic finding is that prognathism (jaw protrusion) is associated with Austro-Melanesians and sub-Saharan Africans, and facial flatness with East Asians, while Europeans, West Asians and North Africans (Caucasoids) generally lack both of these features.

Frontal and Facial Flatness of Major Human Populations

Tsunehiko Hanihara (2000)
Am J Phys Anthro


The standardized coefficients for the variables of the first factor indicate the relationship between the prominence of the infraglabellar notch, prognathism, and frontal flatness in the sagittal plane and frontoorbital flatness and, to a lesser extent, nasal flatness. The plots of the samples on the first canonical variates, based on the scores of the canonical variables in each sample, are presented in Figures 7a,b. The first variable group (Fig. 7a) opposes the Australian/Melanesian samples to the east/northeast Asian samples. The positive, or Australian/Melanesian end, reflects a relatively prominent infraglabellar notch and marked prognathism with a sagittally flat frontal bone. Some of subSaharan African samples are plotted on the positive or Australian/Melanesian side. On the other hand, the European samples, together with the north African, west Asian, and Indian subcontinent samples, are scattered on the opposed side. Figure 7b indicates the magnitude of the projection of midfacial region in the transverse plane without prognathism. The positive end, reflecting flat fronto-orbital and nasal portions, signals a decided eastern Asian and Pacific configuration together with some subSaharan African samples. The degree of facial projection of some New World samples and Australian samples is comparable to those of samples from south Asia to Europe through west Asia and north Africa.

[ See link below for sample details ]


The results presented herein suggest that the features relating to frontal and facial flatness are largely confined to populations from differing world regions: 1) the considerable flatness of the faces of east/northeast Asians, and to a lesser extent, of southeast Asians; 2) morphological complexes such as a deep infraglabellar notch and sagittally flat frontal bone with facial prognathism in Australians and Melanesians; 3) rounded forehead comparable to that in northeast Asians and transversely projecting faces as in Europeans found in the New World populations; 4) eastern Asian-like features in Polynesians and Micronesians, except for a projecting zygomaxillary region; 5) midfacial projection without prognathism in Europeans and related populations such as south and west Asians as well as north Africans; and 6) remarkable prognathism and very flat nasal bones in SubSaharan Africans.

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dave said...

Prognathism seems to have its basis w/a head shape that includes an occidental bun. It seems to be a recessive trait hidden in all people. These protrusions seem to reoccur in populations after a selective sweep of plague or extreme stress. This head shape masks an alternate gene-pool w/a superior survival system, it appears. From 1670-1770 this head shape suddenly became 20% of British population, that were buried in graveyards. It faded away just as suddenly. To explain this; multiple selective sweeps favoring an alternative gene-pool, that peaked in 1700, or,. Epigenetic flip, triggered by disease, drugs or pollution. It is pretty rare in Briton these days,. but it is still seen in the, "buck-toothed", Irish. Look at historical images of the Irish, the older the image, the more pronounced the prognathism. The Irish images support the archeology of the graveyards and draws into question your, geographical distribution conclusion, however, thank you for your interest in the subject.