Abstract
In the context of Middle and Late Pleistocene eastern Eurasian human crania, the external auditory exostoses (EAE) of the late archaic Xuchang 1 and 2 and the Xujiayao 15 early Late Pleistocene human temporal bones are described. Xujiayao 15 has small EAE (Grade 1), Xuchang 1 presents bilateral medium EAE (Grade 2), and Xuchang 2 exhibits bilaterally large EAE (Grade 3), especially on the right side. These cranial remains join the other eastern Eurasian later Pleistocene humans in providing frequencies of 61% (N = 18) and 58% (N = 12) respectively for archaic and early modern human samples. These values are near the upper limits of recent human frequencies, and they imply frequent aquatic exposure among these Pleistocene humans. In addition, the medial extents of the Xuchang 1 and 2 EAE would have impinged on their tympanic membranes, and the large EAE of Xuchang 2 would have resulted in cerumen impaction. Both effects would have produced conductive hearing loss, a serious impairment in a Pleistocene foraging context.
Highlights
Dense bony growths protruding into the external auditory canal, external auditory exostoses (EAE), have been documented clinically for more than a century (e.g., [1,2]), known anthropologically since at least the analyses of Hrdlička [3], and summarized extensively more recently [4,5,6]
EAE were recently noted in the two early Late Pleistocene partial neurocrania from Xuchang [19], but they have not been mentioned for the aged Xujiayao 15 temporal bone [20]. Given these paleopathological and distributional considerations, we present here these bony auditory growths in the Xuchang and Xujiayao late archaic humans, and evaluate their implications in the contexts of the available Middle and Late Pleistocene eastern Eurasian human remains and the patterns of frequencies across recent human skeletal samples
The crania were excavated as 26 and 16 pieces respectively, and the elements have been kept separate, the crania having been reconstructed virtually and with casts. They derive from young adults, and there is no evidence of abnormalities on them, other than the EAE presented here
Summary
Dense bony growths protruding into the external auditory canal, external auditory exostoses (EAE), have been documented clinically for more than a century (e.g., [1,2]), known anthropologically since at least the analyses of Hrdlička [3], and summarized extensively more recently [4,5,6]. The most frequently observed irritant is cold water, in the context of cold water sports and foraging They may occur in a variety of contexts, given sufficient inflammation of the soft tissue lining of the auditory canal. They are often benign but can lead to cerumen impaction and conductive hearing loss
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