Although broomcorn and foxtail millet are among the earliest staple crop domesticates, their spread and impacts on demography remain controversial, mainly because of the use of indirect evidence. Bayesian modeling applied to a dataset of new and published radiocarbon dates derived from domesticated millet grains suggests that after their initial cultivation in the crescent around the Bohai Sea ca. 5800 BCE, the crops spread discontinuously across eastern Asia. Our findings on the spread of millet that intensified during the fourth millennium BCE coincide with published dates of the expansion of the Sino-Tibetan languages from the Yellow River basin. In northern China, the spread of millet-based agriculture supported a quasi-exponential population growth from 6000 to 2000 BCE. While growth continued in northeastern China after 2000 BCE, the Upper/Middle Yellow River experienced decline. We propose that this pattern of regional divergence is mainly the result of internal and external anthropogenic factors.

https://advances.sciencemag.org/content/advances/5/9/eaax6225.full.pdf

Discontinuous spread of millet agriculture in eastern Asia and prehistoric population dynamics

Although the climate development over the Holocene in the Northern Hemisphere is well known, palaeolimnological climate reconstructions reveal spatiotemporal variability in northern Eurasia. Here we present a multi-proxy study from north-eastern Siberia combining sediment geochemistry, and diatom and pollen data from lake-sediment cores covering the last 38,000 cal. years. Our results show major changes in pyrite content and fragilarioid diatom species distributions, indicating prolonged seasonal lake-ice cover between ∼13,500 and ∼8900 cal. years BP and possibly during the 8200 cal. years BP cold event. A pollen-based climate reconstruction generated a mean July temperature of 17.8 °C during the Holocene Thermal Maximum (HTM) between ∼8900 and ∼4500 cal. years BP. Naviculoid diatoms appear in the late Holocene indicating a shortening of the seasonal ice cover that continues today. Our results reveal a strong correlation between the applied terrestrial and aquatic indicators and natural seasonal climate dynamics in the Holocene. Planktonic diatoms show a strong response to changes in the lake ecosystem due to recent climate warming in the Anthropocene.

We assess other palaeolimnological studies to infer the spatiotemporal pattern of the HTM and affirm that the timing of its onset, a difference of up to 3000 years from north to south, can be well explained by climatic teleconnections. The westerlies brought cold air to this part of Siberia until the Laurentide ice-sheet vanished 7000 years ago. The apparent delayed ending of the HTM in the central Siberian record can be ascribed to the exceedance of ecological thresholds trailing behind increases in winter temperatures and decreases in contrast in insolation between seasons during the mid to late Holocene as well as lacking differentiation between summer and winter trends in paleolimnological reconstructions.

Late Quaternary vegetation and lake system dynamics in north-eastern Siberia: Implications for seasonal climate variability

This research has been supported by the Swiss National Science Foundation (grant no. 200021_169598), with additional support from the University of Lausanne.

/pdf/the-eurasian-modern-pollen-database-empd-version-2-22zhn35uzf.pdf

The Eurasian Modern Pollen Database (EMPD), version 2

Anthropogenic activities have led to a global decline in biodiversity, and monitoring studies indicate that both insect communities and wetland ecosystems are particularly affected. However, there is a need for long-term data (over centennial or millennial timescales) to better understand natural community dynamics and the processes that govern the observed trends. Chironomids (Insecta: Diptera: Chironomidae) are often the most abundant insects in lake ecosystems, sensitive to environmental change, and, because their larval exoskeleton head capsules preserve well in lake sediments, they provide a unique record of insect community dynamics through time. Here, we provide the results of a metadata analysis of chironomid diversity across a range of spatial and temporal scales. First, we analyse spatial trends in chironomid diversity using Northern Hemispheric data sets overall consisting of 837 lakes. Our results indicate that in most of our data sets, summer temperature (Tjul ) is strongly associated with spatial trends in modern-day chironomid diversity. We observe a strong increase in chironomid alpha diversity with increasing Tjul in regions with present-day Tjul between 2.5 and 14°C. In some areas with Tjul  > 14°C, chironomid diversity stabilizes or declines. Second, we demonstrate that the direction and amplitude of change in alpha diversity in a compilation of subfossil chironomid records spanning the last glacial-interglacial transition (~15,000-11,000 years ago) are similar to those observed in our modern data. A compilation of Holocene records shows that during phases when the amplitude of temperature change was small, site-specific factors had a greater influence on the chironomid fauna obscuring the chironomid diversity-temperature relationship. Our results imply expected overall chironomid diversity increases in colder regions such as the Arctic under sustained global warming, but with complex and not necessarily predictable responses for individual sites.

Temperature change as a driver of spatial patterns and long-term trends in chironomid (Insecta: Diptera) diversity.

/pdf/an-8500-year-palynological-record-of-vegetation-climate-34fsjfmq74.pdf

An 8500-year palynological record of vegetation, climate change and human activity in the Bosten Lake region of Northwest China

Vegetation change and human impacts on Rebun Island (Northwest Pacific) over the last 6000 years

A multi-proxy palaeolimnological record of the last 16,600 years from coastal Lake Kushu in northern Japan

Late Quaternary Lake Dynamics in the Verkhoyansk Mountains of Eastern Siberia: Implications for Climate and Glaciation History

1 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Telegrafenberg, 14473 Potsdam, Germany,  2 North-Eastern Federal University of Yakutsk, Institute of Natural Sciences, ul. Belinskogo 58, 677000 Yakutsk, Russia,  3 University of Potsdam, Institute for Earth and Environmental Sciences, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany. 4 Karelian Research Centre of Russian Academy of Sciences, Northern Water Problems Institute, Petrozavodsk, Russia. 5 Free University Berlin, Institute of Geological Sciences, Palaeontology, Malteserstraße 74-100, Building D, 12249 Berlin, Germany. 6 RWTH Aachen University, Department of Geography, Templergraben 55, 52056 Aachen, Germany Aachen. 7 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 27568 Bremerhaven, Am Alten Hafen, Germany.

Rebun Island with Hamanaka and Funadomari among the 43 documented archaeological sites and the environmental archive stored in the Lake Kushu sediment proves to be one of the key areas to study the interplay between ecology, climate and human activities. A set of 57 radiocarbon dates of the RK12 core (Lake Kushu) demonstrates that it represents a continuous environmental archive covering the last c. 17,000 years. The RK12 pollen record reflects distinct vegetation changes. After c. 1100 cal. BP, arboreal pollen percentages decrease, possibly linked to intensified usage of wood during the Okhotsk and Ainu culture periods. Plant macrofossil analysis shows use of various wild plants and also domesticated barley during the Okhotsk and Ainu periods.

/pdf/hokkaido-japan-archaologie-in-der-region-hokkaido-g2dqtp3umu.pdf

Stefanie Müller

Papers

Vegetation change and human impacts on Rebun Island (Northwest Pacific) over the last 6000 years

A multi-proxy palaeolimnological record of the last 16,600 years from coastal Lake Kushu in northern Japan

Late Quaternary Lake Dynamics in the Verkhoyansk Mountains of Eastern Siberia: Implications for Climate and Glaciation History

Late Quaternary Lake Dynamics in the Verkhoyansk Mountains of Eastern Siberia: Implications for Climate and Glaciation History

Hokkaido, Japan: Archäologie in der Region Hokkaido: Naturumwelt der holozänen Jäger und Sammler