X men

Kevin Lewis

June 09, 2019

From Cosmic Explosions to Terrestrial Fires?
Adrian Melott & Brian Thomas
Journal of Geology, forthcoming


Multiple lines of evidence point to one or more moderately nearby supernovae, with the strongest signal at ∼2.6 Ma. We build on previous work to argue for the likelihood of cosmic ray ionization of the atmosphere and electron cascades leading to more frequent lightning and therefore an increase in nitrate deposition and wildfires. The potential exists for a large increase in the prehuman nitrate flux onto the surface, which has previously been argued to lead to CO2 drawdown and cooling of the climate. Evidence for increased wildfires exists in an increase in soot and carbon deposits over the relevant period. The wildfires would have contributed to the transition from forest to savanna in northeast Africa, long argued to have been a factor in the evolution of hominin bipedalism.

Valkyries: Was Gender Equality High in the Scandinavian Periphery since Viking Times? Evidence from Enamel Hypoplasia and Height Ratios
Laura Maravall Buckwalter
Economics & Human Biology, forthcoming


Scandinavian countries currently have very high values of female autonomy. Was this already the case in Viking Times? In this study, we trace the roots of gender equality in the Scandinavian periphery over the past two millennia. We evaluate and recommend a new measure of early gender equality: relative enamel hypoplasia values of males and females. This new indicator allows us to trace relative health and nutritional equality, using archaeological evidence. We find that Scandinavian women in the rural periphery already had relatively good health and nutritional values during the Viking era and the medieval period thereafter. The corresponding value is 0.8 equality advantage for Scandinavian women, whereas in the rest of Europe most values fall in a band around 1.2 ratio units. This suggests that the currently high gender equality had a precedence during the Middle Ages.

Living on the edge: Was demographic weakness the cause of Neanderthal demise?
Anna Degioanni et al.
PLoS ONE, May 2019


The causes of disappearance of the Neanderthals, the only human population living in Europe before the arrival of Homo sapiens, have been debated for decades by the scientific community. Different hypotheses have been advanced to explain this demise, such as cognitive, adaptive and cultural inferiority of Neanderthals. Here, we investigate the disappearance of Neanderthals by examining the extent of demographic changes needed over a period of 10,000 years (yrs) to lead to their extinction. In regard to such fossil populations, we inferred demographic parameters from present day and past hunter-gatherer populations, and from bio-anthropological rules. We used demographic modeling and simulations to identify the set of plausible demographic parameters of the Neanderthal population compatible with the observed dynamics, and to explore the circumstances under which they might have led to the disappearance of Neanderthals. A slight (<4%) but continuous decrease in the fertility rate of younger Neanderthal women could have had a significant impact on these dynamics, and could have precipitated their demise. Our results open the way to non-catastrophic events as plausible explanations for Neanderthal extinction.

The population history of northeastern Siberia since the Pleistocene
Martin Sikora et al.
Nature, forthcoming


Northeastern Siberia has been inhabited by humans for more than 40,000 years but its deep population history remains poorly understood. Here we investigate the late Pleistocene population history of northeastern Siberia through analyses of 34 newly recovered ancient genomes that date to between 31,000 and 600 years ago. We document complex population dynamics during this period, including at least three major migration events: an initial peopling by a previously unknown Palaeolithic population of ‘Ancient North Siberians’ who are distantly related to early West Eurasian hunter-gatherers; the arrival of East Asian-related peoples, which gave rise to ‘Ancient Palaeo-Siberians’ who are closely related to contemporary communities from far-northeastern Siberia (such as the Koryaks), as well as Native Americans; and a Holocene migration of other East Asian-related peoples, who we name ‘Neo-Siberians’, and from whom many contemporary Siberians are descended. Each of these population expansions largely replaced the earlier inhabitants, and ultimately generated the mosaic genetic make-up of contemporary peoples who inhabit a vast area across northern Eurasia and the Americas.

The origins of specialized pottery and diverse alcohol fermentation techniques in Early Neolithic China
Li Liu et al.
Proceedings of the National Academy of Sciences, forthcoming


In China, pottery containers first appeared about 20000 cal. BP, and became diverse in form during the Early Neolithic (9000-7000 cal. BP), signaling the emergence of functionally specialized vessels. China is also well-known for its early development of alcohol production. However, few studies have focused on the connections between the two technologies. Based on the analysis of residues (starch, phytolith, and fungus) adhering to pottery from two Early Neolithic sites in north China, here we demonstrate that three material changes occurring in the Early Neolithic signal innovation of specialized alcoholic making known in north China: (i) the spread of cereal domestication (millet and rice), (ii) the emergence of dedicated pottery types, particularly globular jars as liquid storage vessels, and (iii) the development of cereal-based alcohol production with at least two fermentation methods: the use of cereal malts and the use of moldy grain and herbs (qu and caoqu) as starters. The latter method was arguably a unique invention initiated in China, and our findings account for the earliest known examples of this technique. The major ingredients include broomcorn millet, Triticeae grasses, Job’s tears, rice, beans, snake gourd root, ginger, possible yam and lily, and other plants, some probably with medicinal properties (e.g., ginger). Alcoholic beverages made with these methods were named li, jiu, and chang in ancient texts, first recorded in the Shang oracle-bone inscriptions (ca. 3200 cal. BP); our findings have revealed a much deeper history of these diverse fermentation technologies in China.

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