Early Skeletons from Tranquillity, California

Abstract

From these speculations one can draw three conclusions, differing in certainty.<br/>The most certain one is that the first invaders from Asia, the Palaeamericans, migrating southward over a timespan of 5-10,000 years after the height of the last glaciation (Willey, 1961), split up into many slightly differing breeding isolates, whose divergences occurred more through sampling accidents (drift) than through selection. The kind of variability of the Tranquillity sample, especially the extreme in Burial 5, supports this picture.<br/>The least certain, conclusion concerns evolutionary selective pressures resulting from a tough meat diet and hard living conditions leading to a short lifespan. These pressures would put a high premium on the fertility of a few women, especially those having massive teeth to resist wear (cf. Brace, 1962). Possibly Mongoloid features are a result of such pressures. The source for this extra tooth and face size not yet fully developed in late Pleistocene East Asia might be a recombination of genes from a tropical Negritoid population (contributing canine plus incisor breadth and prognathism) with genes from Sinanthropus descendants like Mapa (Woo, 1959 b; Coon, 1962) contributing shovel incisors and face massiveness, and perhaps also with Upper Paleolithic "White" genes. Evolution from such a proto-Mongoloid blend in a Mongoloid direction would have occurred in both Asia and America after 20,000 B.C. Apparently this evolution went much further in Asia.<br/>The third conclusion concerns this difference in speeds of microevolution. The Tranquillity group in particular is still proto-Mongoloid and modern Hill Yokuts, Southern Miwok, and Western Mono appear to have changed little from it. Until very recently the tule-swamp character of the region had changed very little, except for the gradual (and late &amp;quest;) extinction of most larger game mammals other than deer, and the ensuing wet phase. Regions of climatic and ecologic stability during the retreat of the last glaciation would probably be influenced by maritime climate and separated from the North or Plains areas.<br/>In contrast to this, Northeast Asia, the Bering Strait region, and northern North America underwent a series of climatic and sea level changes comparable to those of Europe and the Mediterranean. Here there took place an evolutionary change to a big-faced, large-headed fully Mongoloid norm, equivalent to the Upper Paleolithic to Alpine and Mediterranean change in Europe and the Near East. A little of this Mongoloid change was plausibly injected into America in early Mesolithic times, and again to form the Aleut-Eskimo people (Laughlin, 1963) before 6,000 B.C. Until we have more data on frequencies of key traits and complexes, it is hard to guess whether the American Indian in general has absorbed Asiatic genes to any extent in post-Pleistocene times: the probable relation of Diego blood type to a Palaeamerican distribution and the lack of type B in the New World suggest that there was little addition from Asia after the end of the Pleistocene. In that case we are faced with an interesting parallelism in evolution in a Mongoloid direction, with the slower rate of change in America partly explained by relative climatic stability of southern coastal, island, mountain, jungle, and woodland ecologic zones as opposed to northern coastal, plateau, and plains areas, even though the variety of American ecologic zones is wide.