Fueguian cranial morphology: The adaptation to a cold, harsh environment

Abstract

Craniometric data from the three extinct tribes that inhabited Tierra del Fuego (Selk'nam, Yámana, and Kawéskar) were gathered following Howell's measurement technique. We studied 180 skulls preserved at thirteen different institutions. Analysis of variance (ANOVA) between groups showed that morphological similarities among Fueguian groups are far more important than some differences between marine (Yámana and Kawéskar) and terrestrial (Selk'nam) groups. A principal component analysis (PCA) generated from the correlation matrix shows that Fueguians fall as outliers with respect to the typical Mongoloid morphology. In addition, a UPGMA tree generated from a squared Euclidean distance matrix indicates that Fueguian groups have a morphological pattern that is very distinct from that of other present-day Amerindian groups, with the exception of the Eskimos. One of the variables that contributes substantially to the differentiation of Eskimos and Fueguians is the nasal height. This suggests that nasal morphology in both groups could be a response to adaptive pressures related to the cold environment. However, other morphological particularities of Fueguian skulls, such as craniofacial robustness and variables of craniofacial width, can be attributed to a large masticatory stress. As a whole, the morphological features of Fueguian groups can be regarded as a general adaptive response to a very harsh environment, along with the retention of some plesiomorphic features. Assuming that the initial entry in Tierra de Fuego took place around 10,000 years BP, before the disappearance of the last land bridges in the Magellan Straits, then this adaptation might have arisen in a relatively short period, hastened by the extreme environmental conditions.

Nonrandom Factors in Modern Human Morphological Diversification: A Study of Craniofacial Variation in Southern South American Populations

“…The climate could have a particularly important influence over populations inhabiting the southernmost South American region, known as Tierra del Fuego. This region has a harsh climate, with strong winds and occasional winter temperatures of −20 • C. The combination of wind, cold, and rain, makes Tierra del Fuego a challenging environment for humans (Hernández et al 1997). However, the Fueguians lived almost naked and Beagle Channel's (Yámana) and Austral Islander (Kawéskar) females swam frequently in the extremely cold water to collect mollusks (Hernández et al 1997).…”

The Prehistoric Development of Clothing: Archaeological Implications of a Thermal Model

“…121-123). Osteological analyses indicate a degree of morphological cold adaptation among Fuegan groups (e.g., Hernández et al 1997), probably accompanied by the physiological measures-such as acclimatizationdocumented among other cold-exposed modern groups, enhancing their capacity to cope with cold stress and reducing their need for clothes. However, studies in thermal physiology confirm that any such physical adaptations confer only limited benefits, and the level of cold tolerance shown by Fuegans does not undermine a thermal model for clothing origins, as has been claimed (e.g., Horn and Gurel 1981, p. 25;Barthes, in Carter 2003, p. 153).…”

Ontogeny of robusticity of craniofacial traits in modern humans: A study of South American populations

“…The comparison of craniofacial morphology of several Holocene samples from this region shows high levels of variation in cranial robusticity . Whereas the final late Holocene samples from southernmost Patagonia and Tierra del Fuego exhibit high levels of robusticity, the earlier samples from this region, as well as those from other regions of South America, show lesser development of robust features (Lahr, 1995;Lahr and Wright, 1996;Hernandez et al, 1997;Lalueza et al, 1997;Bernal et al, 2006). The mtDNA, Y chromosome and specific microsatellite loci analyses of modern and extinct Native Americans support a recent common ancestry for all American populations and a single expansion into America of groups from Northeast Asia, indicating that they have a single ancestral gene pool (Moraga et al, 2000;García-Bour et al, 2004;Schurr, 2004;Goebel et al, 2008).…”