Does a parasite have a better chance of survival if an Inuit or a Mayan spits on it?

An earlier puzzling observation [Shields and Mann, J Craiofac Genet Dev Biol, 16:126-136, 1996] that the prevalence of a polymorphic male predominate, major salivary gland-associated, static lesion of the mandible increased exponentially from the Arctic to the Tropics was explained by both positive and negative selection (balancing) on major salivary gland endocrine and exocrine factors. Additional prevalence rates presented here identified three high prevalence high-Temperate zone cultures that were unusually exposed to alimentary parasites. A correlation between macroparasite exposure and the mandibular lesion helped refine the potential selective forces that fashioned major salivary gland size variation. The data suggests that positive selection occurred for androgen-induced enlargement of the suite of major salivary glands and consequently increased quantities of factors. Increased quantities of salivary gland biologically active factors enhance innate protection against infestation of macroparasites per se, especially gut parasites. The data further suggests that negative selection against enlarged salivary glands occurred as protection against electrolyte imbalances in electrolyte stressed environments and in females.

Dorset and Thule divergence from East Central Asian roots.

The history of the immigration of East Asians to America during the last glacial period remains controversial. In an attempt to add critical data to this problem, a large sample of whole teeth derived from Southeast Asian, Mongolian, Thule, Western Inuit, and pre-Inca (Huari) people was quantified (N = 4,507 teeth from 495 individuals; approximately 30 variables per tooth). Multivariate analysis helped establish that all Native Americans were likely derived from one ancient, extinct population that resided in the region of Mongolia (east Central Asia), and that Mongolians and Southeast Asians are two independent groups. A controversial and enigmatic Central Canadian Arctic "Thule culture Inuit" group on Southampton Island that survived until 1902 was identified as a relic, mainly Paleoeskimo Dorset community. Surprisingly, there was little, or no, indication of Dorset-to-Thule gene flow. Cumulatively, the data suggest that a small population of Paleoindian founders remained resident in Beringia, may have blocked further immigration, and were the antecedents to the Thule/Inuit. With the confluence of the Arctic and Pacific oceans at the breakup of Beringia, the resulting increased availability of marine animal food sources allowed this population to increase in size and expand throughout the eastern Arctic.