Bone density and genomic analysis unfold cold adaptation mechanisms of ancient inhabitants of Tierra del Fuego

Abstract

The Fuegians, ancient inhabitants of Tierra del Fuego, are an exemplary case of a cold-adapted population, since they were capable of living in extreme climatic conditions without any adequate clothing. However, the mechanisms of their extraordinary resistance to cold remain enigmatic. Brown adipose tissue (BAT) plays a crucial role in this kind of adaptation, besides having a protective role on the detrimental effect of low temperatures on bone structure. Skeletal remains of 12 adult Fuegians, collected in the second half of XIX century, were analyzed for bone mineral density and structure. We show that, despite the unfavorable climate, bone mineral density of Fuegians was close to that seen in modern humans living in temperate zones. Furthermore, we report significant differences between Fuegians and other cold-adapted populations in the frequency of the Homeobox protein Hox-C4 (HOXC4) rs190771160 variant, a gene involved in BAT differentiation, whose identified variant is predicted to upregulate HOXC4 expression. Greater BAT accumulation might therefore explain the Fuegians extreme cold-resistance and the protection against major cold-related damage. These results increase our understanding of how ecological challenges have been important drivers of human–environment interactions during Humankind history.

Castration and emasculation in the Middle Age. The andrological conundrum of Peter Abelard

“…(iii) dual-energy X-ray absorptiometry (DXA) 77 ; (iv) near-infrared spectroscopy for gauging the collagen content 78 ; (v) if authorized,…”

“…A study could be planned to establish the age of the specimens, the gender, the possible diseases, and the presence and degree of osteoporosis. For this purpose, the bones could be subjected to (i) microphotography of all samples; (ii) computed tomography (CT); (iii) dual‐energy X‐ray absorptiometry (DXA) 77 ; (iv) near‐infrared spectroscopy for gauging the collagen content 78 ; (v) if authorized, radiocarbon dating 79 ; (vi) if authorized, ancient DNA analysis 80 ; (vii) if authorized, inductively coupled plasma mass spectrometry (ICP‐MS) 81 performed for establishing or unraveling diet and social status of the deaths and finding trace elements of Ca, Mn, Fe, Cu, Sr, Ba, and Pb. Note that methods of the points (i)–(iv) do not need destruction of the samples, while methods (v)–(vii) are based on the destruction of micro‐fragments of the specimens, that is, about 1–2 mm (roughly, 1–40 mg), for each examination.…”