The Holocene

Radiocarbon dates from 176 sites along the Delmarva Peninsula record the timing of deposition and sea-level rise, and non-marine wetland deposition. The dates provide confirmation of the boundaries of the Holocene subepochs (e.g. “early-middle-late” of Walker et al.) in the mid-Atlantic of eastern North America. These data record initial sea-level rise in the early Holocene, followed by a high rate of rise at the transition to the middle Holocene at 8.2 ka, and a leveling off and decrease in the late-Holocene. The dates, coupled to local and regional climate (pollen) records and fluvial activity, allow regional subdivision of the Holocene into six depositional and climate phases. Phase A (>10 ka) is the end of periglacial activity and transition of cold/cool climate to a warmer early Holocene. Phase B (10.2–8.2 ka) records rise of sea level in the region, a transition to Pinus-dominated forest, and decreased non-marine deposition on the uplands. Phase C (8.2–5.6 ka) shows rapid rates of sea-level rise, expansion of estuaries, and a decrease in non-marine deposition with cool and dry climate. Phase D (5.6–4.2 ka) is a time of high rates of sea-level rise, expanding estuaries, and dry and cool climate; the Atlantic shoreline transgressed rapidly and there was little to no deposition on the uplands. Phase E (4.2–1.1 ka) is a time of lowering sea-level rise rates, Atlantic shorelines nearing their present position, and marine shoal deposition; widespread non-marine deposition resumed with a wetter and warmer climate. Phase F (1.1 ka-present) incorporates the Medieval Climate Anomaly and European settlement on the Delmarva Peninsula. Chronology of depositional phases and coastal changes related to sea-level rise is useful for archeological studies of human occupation in relation to climate change in eastern North America, and provides an important dataset for future regional and global sea-level reconstructions.

Climate change and human activities have been an important part of studies regarding historical environmental changes in China over the past 2000 years. In this study, we focused on environmental changes, that is, natural disasters and human activities, in the Poyang Lake Basin over the past 2000 years, to analyze interactions between land use cover changes and human activities from the perspective of regional sustainable development. We collected historical records of climate and hydrology, floods and droughts, and rivers and lakes in the Poyang Lake area, and established time sequences for the floods and droughts, lake water level and lake area, amount of farming land, and population, in order to discuss interactions between changes in the environment and the climate, with emphasis on the impacts of extreme events on lake and river basin environment changes. The following results were obtained. First, climate changes in historical periods had wide-ranging and far-reaching impacts on agricultural production, especially disasters caused by climate change. Among the changes in the Poyang Lake basin environment, including river network systems, lake water levels, etc., changes in lake water volume are direct evidence of climate change, adaptation to climate change, and obvious phased characteristics. Second, in the process of changes to the lake and river network in the Poyang Lake Basin, social and economic development is accompanied by evolution of the lake. Increases and decreases in population, the scale of agricultural production, and lake environment changes have direct and significant interactions. Third, the Poyang Lake basin’s environmental changes during the historical period are mainly reflected in the pressure feedback mode of “population–agriculture” in the lake environment.

Soil erosion is one of the greatest risks worldwide for land degradation. Avoiding it is one of the greatest socio-environmental and economic challenges within sustainable development in connection with food production and maintenance of soil functions in the context of climate change. This study will allow us to answer how long-term occupation dynamics influenced by notable changes in the landscape have led to soil erosion through time. We used Geographical Information Systems to apply the Revised Universal Soil Loss Equation to assess soil erosion on prehispanic and present occupation scenarios that differ in climate and land use management in the Teotihuacan Valley, central Mexico. We analyzed how a heterogeneous landscape and its occupation dynamics over the last two millennia were affected by soil erosion in order to identify which biophysical and anthropogenic components affect soil loss. The settlements extended during Aztec periods over previously forested hillslopes which caused an increase in erosion rates. The greatest soil loss occurred during the humid Aztec period, followed by the Modern period. The differences between average erosion and potential erosion of these periods demonstrate greater effectiveness in controlling erosion during the Aztec period. The most relevant factors involved were land use and soil management, followed by climate and support practices. Our results indicate that in the face of climatic variations, soil management has a significant impact, even greater than rain erosivity. Our results suggest that pre-Hispanic cultures in the highlands of central Mexico may have caused soil erosion at least at rates similar to or even higher than those at present. The comparisons of the scenarios enable researchers and decision makers to identify high-risk areas and to implement sustainable measures against soil erosion.

The Cape Canaveral Peninsula is the largest Holocene coastal sand deposit composed of beach ridges on the Atlantic coast of Florida. It is composed of 16 beach-ridge sets that are separated by erosional surfaces. Despite its prominence as a Holocene coastal depocenter, there are a limited amount of chronological data constraining the timing of its formation. In this study, we apply optically stimulated luminescence (OSL) dating on sand-sized quartz and radiocarbon dating on individual marine shells to develop a refined chronology of the Cape Canaveral beach-ridge plain with particular focus on constraining the depositional age of the northwesterly-most, and geographically oldest, beach-ridge set on the peninsula. We obtain an average OSL age of 5680 ± 240 years (n = 4) for the initiation of coastal deposition at Cape Canaveral. The new ages, and the organization of beach ridges into 16 distinct sets indicates that the Cape Canaveral beach-ridge plain experienced an ~5700-year history of alternating deposition and erosion, with 75% of present-day Cape Canaveral (Beach-ridge Sets 5–16) deposited over the past 2000 years and Beach-ridge Sets 8–16 comprising 50% of the area over the past 1000 years. Because the minimum swale elevations of the ~5700-year Beach-ridge Set 1, and those of all the younger beach-ridge sets, are within several decimeters of present-day mean higher high water, we hypothesize that all the beach ridges present at Cape Canaveral could have been deposited at or within decimeters of present-day sea level. There is no evidence for Holocene “highstand” events over the past 5700 years in the published sea level curves from northeast and south Florida, which are based on subsurface estuarine foraminifera/leaf litter and mangrove peat data, respectively. This dichotomy illustrates the need to integrate both subaerial and subsurface data to produce a more realistic Holocene sea-level curve for the southeastern United States.

Training animals to pull agricultural equipment and wheeled transport significantly shaped and advanced human economic systems. In this context the use of large domestic animals such as cattle was a milestone event in human history, part of what Sherratt memorably termed the Secondary Products Revolution: the use of the products of live animals such as milk, wool and traction power. It is commonly assumed that male cattle were generally preferred for traction because of their greater strength compared with females, and the importance of the latter for breeding and, in some societies, for milk and for dairy products, but surprisingly little is known of this aspect of the Secondary Products Revolution in prehistoric China. Here we apply established morphometric models to 10 assemblages of cattle bones from Chinese Bronze Age (ca. 2000–221 BCE) contexts. Our results indicate a process of intensified cattle labour exploitation at this time and, intriguingly, we also observe the earliest labour employment of female cattle during the Late Shang dynasty (ca. 1300–1046 BCE). It is proposed that female cattle may have been required for traction because of the large numbers of male cattle, especially bulls, that were sent for ritual sacrifice. Such a strategy reveals a sophisticated social management, upon which the Late Shang civilisation eventually developed.

Experimental paleoparasitological approaches have been used in order to optimize the methodology previously to the application in archeological samples. In this study we evaluated the action of dehydration and local soil (Central Argentina) on the loss of parasite eggs in experimental coprolites, using two parasitological techniques: spontaneous sedimentation and sucrose-flotation. Experimental coprolites comprised fresh human feces, positive for Hymenolepis nana, Ascaris sp., and Enterobius vermicularis, submitted to controlled artificial dehydration. Experimental coprolites with soil addition were prepared by mixing archeological sediment with equal mass of fresh feces. Helminth eggs were counted and eggs per gram were estimated in each subsample. Statistical analyses were applied to compare subsamples before and after desiccation and with and without addition of soil sediment. The performance of parasitological methods statistically differed, the sucrose flotation technique being the less effective when fresh feces and experimental coprolites were analyzed. Partial deformation of eggs was observed via both techniques only in subsamples containing H. nana eggs. However, this was not seen in Ascaris sp. subsamples, possibly due to eggshell composition. We found that sample desiccation significantly decreased the number of eggs in the experimental coprolites. Mixing archeological sediment with the fecal material also resulted in significantly fewer eggs surviving, independent of desiccation. This shows that climate and soil in which archeological fecal samples are found can strongly influence the survival of parasite eggs from past populations. The small amount of parasite evidence often found in paleoparasitological analyses, including Central Argentina, could be attributed to the action of taphonomic processes rather than to the real absence of infection in these ancient populations. Importantly, the study highlights the role of local soil, confirmed for the first time by empirical data. The research provides valuable insights into the understanding of the paleoparasitological results of the region and of general paleoparasitology.