Studies of the peopling of the Americas have focused on the timing and number of initial migrations. Less attention has been paid to the subsequent spread of people within the Americas. We sequenced 15 ancient human genomes spanning from Alaska to Patagonia; six are ≥10,000 years old (up to ~18× coverage). All are most closely related to Native Americans, including those from an Ancient Beringian individual and two morphologically distinct “Paleoamericans.” We found evidence of rapid dispersal and early diversification that included previously unknown groups as people moved south. This resulted in multiple independent, geographically uneven migrations, including one that provides clues of a Late Pleistocene Australasian genetic signal, as well as a later Mesoamerican-related expansion. These led to complex and dynamic population histories from North to South America.

Fuego-Patagonia's marine and terrestrial groups were historically described as phenotypically distinct but, studies of these phenotypic differences have yet to be conducted. This study evaluates phenotypic variation in Fuego-Patagonia. Phenotypic disparities result from extrinsic and intrinsic factors and therefore can reveal differences in both long and short term adaptations as well as genetic differences. Fifty-one adults were assessed. A total of six post-cranial measurements were included: maximum length of the humerus (MHL); maximum length of the radius (MRL); Bicondylar length of the femur (BFL); Maximum length of the tibia (MTL); bi-iliac breadth (BIB), and; antero-posterior diameter of the femoral head (FHD). Brachial index, crural index, body mass, body mass index and stature were then calculated. In general, terrestrial individuals had longer lower limb bones and were the tallest and heaviest. Marine individuals had the shortest bones and were shorter and lighter. Mixed-economy individuals showed mostly intermediate values. The trends are more marked in males than in females. The results suggests the presence of an east-to-west phenotypic gradient in the region that may have resulted from intrinsic and/or extrinsic differences between the groups. But, the sample size of this study is small, and thus the results should be cautiously considered.Key words: Phenotypic variation, Fuego-Patagonia, human colonization. Históricamente grupos marinos y terrestres de Fuego-Patagonia fueron descritos como fenotípicamente distintos. Este estudio examina la presencia de esta variación fenotípica, la cual de existir, podría ser resultado de factores extrínsecos, como son los procesos adaptativos de corto o largo plazo e intrínsecos como son los factores genéticos. La muestra se compone de 51 individuos adultos. Se incluyeron seis mediciones post-craneales: longitud máxima del húmero (MHL); longitud máxima del radio (MRL); longitud bicondilar del fémur (BFL); longitud máxima de la tibia (MTL); ancho bi-ilíaco (BIB), y; diámetro antero-posterior de la cabeza femoral (FHD

Harris lines (HL) are radio-opaque transverse lines traditionally associated with stressors that halt or decelerate growth in humans. Harris lines' status as a stress marker is, however, questionable because their association to illness and deficient growth is low and they commonly form in the absence of stress during periods of accelerated growth. To assess Harris line's reliability as a stress marker, this study examined their association with nutritional status and bone growth velocity through an experimental study in rabbits. Forty-five New Zealand White rabbits were divided into: Control (normal laboratory conditions), Experimental-1 (moderately undernourished), and Experimental-2 (periodically fasted) groups during their growth. Variables analyzed included weight, forelimb length, humeral diaphyseal length, diaphyseal growth velocity, and number of Harris lines. Fewer lines were observed by the end of the study among Experimental-1 animals. More Harris lines formed during periods of rapid growth in the absence of nutritional stress. Accordingly, Harris lines are a poor marker of stress. Intrinsic limitations to paleopathological studies can be overcome, but even the most careful attentiveness to multiple stress markers and cultural context will go amiss if the markers used are unreliable.