Ecology of the past

Over the last two weeks I have been giving my lectures at the VU Amsterdam “Scientific Methods in Archaeology” bachelor program. In my lectures we think about how to detect past environmental change with particular reference to tracking past human activities. As part of our exploration of past human-environment-climate interactions each student is asked to choose a scientific article, summerise it, and we then discuss it in class. The three papers sected this year covered the Neolithic of the Netherlands (Weijdema et al., 2011), a overview of Mediterranean and north African cultural adaptations to drough events during the Holocene (Mercuri et al., 2011), and an exploration of the role of humans in mega-faunal extinctions in South America (Villavicencio et al., 2015). All papers provided interesting points of discussion and an opportunity to think about different aspects of how we investigate past environmental and societal change.

Read the full student summaries below.

Summary of: Weijdema et al. (2011) “Early neolithic human impact on vegetation in a wetland environment in the Noordoostpolder, central Netherlands” by Jordy Jetses

This article is about the Neolithic period in the Noordoostpolder. A sediment profile has been made in the Schokkerhaven near the former island of Schokland. From this sediment profile, layers have been recognized and samples have been taken. There were samples of microfossils as well as macrofossils. But before we’re going to discuss the results, we need to know something about the region.

The Noordoostpolder was positioned in the valley of the rivers Vecht and IJssel. The landscape was formed by those rivers and the Saalien and Weichselien ice age periods. Push moraines were formed and made Schokland higher in the landscape than the surrounding area. The formation of river dunes on top of the Schokland push moraine made the height differences even bigger.

The stratigraphy of the sediment layers were split in different zones ranging from zone I to V. Zone Ia is thought to date in the Atlantic period and has no peat records. Zone Ib saw changes between a drier and wetter climate and a small forest on Schokland was formed. During the period of zone II, the landscape opened up and became more eutrophic.  Then in the zone III period the remaining alnus forest disappeared and was replaced by a salix forest. During zone IVa, the Noordoostpolder was a eutrophic swamp and in the period of IVb, the swamp contained many more small pools and the forest on Schokland shrunk. At last during the period of zone V, the Noordoostpolder became open wetland.

During the Neolithic period people from the Swifterband culture lived in the Noordoostpolder and in other parts of nowadays Flevoland. They were originally hunter-gatherers but became farmers in the course of time. Dating of farm related findings in the area like plough traces or cereal remains, show us a start of agriculture around 4200 BC in the surrounding area of Schokland. Humans from the Swifterband culture were present in Schokland during the period of zones Ib/II, with much support for agriculture around 3950-3700 BC. Humans could also be present during the period of zone IV/V, but the only evidence are cereal pollen.

Summary of: Mercuri et al. (2011) “Mediterranean and North-African cultural adaptations to mid-Holocene environmental and climatic changes” by Willem de Jong

This paper focuses on cultural adaptations in the Mediterranean and North-Africa to climatic changes during the mid-Holocene. Pollen records can tell us something about cultivation and human presence and activity in different regions. Charcoal records can shed a light on cases which cannot be sustained by pollen records. In this paper, three main dry events were selected for discussion: c. 8200 cal. yr BP, c. 6000 cal. yr BP, and c. 4200 cal. yr BP. Pollen and charcoal records were sampled on five different sites: (1) Wadi Teshuinat area (Fezzan, Libya, Central Sahara); (2) Benzù cave (Ceuta mountains, Spain, NW Africa); (3) La Vaquera Cave (Central System, Spain); (4) Terramara di Montale (Po Plain, Northern Italy); (5) Arslantepe (Eastern Anatolia, Turkey).

It is thought that climate change had an effect on the way how human societies used their land and developed. The abrupt cooling of 8200-8100 cal. yr BP made regions drier and caused a period of abandonment of settlements. Around c. 6000 cal. yr BP another increase of dryness led to lower lake levels and treeline shifts in central Turkey, in Northern-Africa, lake records show a period of aridification. Around 5000-4000 cal. yr BP the climate around the Mediterranean and North-Africa was getting even drier which had an effect of drastic decline in broadleaved trees and an increase in arid vegetation.

There can be concluded that societies across the studied regions adapted to the change in climate. This change was synchronous but in their own way a culture adapted as different species of vegetation were found in different regions. The change in climate could, for example, be a positive cause of developments for one region, it could also lead to impoverishment of vegetation in other regions and therefore effect human cultures.

Summary of: Villavicencio et al. (2015) “Combination of humans, climate, and vegetation change triggered Late Quaternary megafauna extinction in the Última Esperanza region, southern Patagonia, Chile” by Rik van Noorloos

Near the end of the Pleistocene a great extinction, primarily effecting large mammals, took place all across the world. However, the aftermath was not everywhere the same. In some regions more species died out then in other regions, and in one place the extinction may have taken place earlier then somewhere else. This paper focuses on the region of Patagonia in Chile, and attempts to describe the effects of the extinction as well as determine the cause for the extinction in that region.

After first describing the modern physiology of the region the paper starts with a reconstruction of the flora, fauna and climate in the period of transition between the Pleistocene and the Holocene. Ice accumulation layers, C-14 dating lake cores and charcoal analysis all indicate a drastic drop in temperature between 14500 and 13000 BP, followed by a period of quick temperature increase. The paper also describes the various plant and animal species inhabiting the area in this age.

Lastly the paper talks discusses the arrival of modern humans in Patagonia, and it’s possible relation to the extinction of large mammal species. The first humans appear to have arrived around between 14600 and 13300 BP; shortly before the large predators of the area went extinct. However, they coexisted with many more species such as horses and ground sloths. The sloths of the species Mylodoncontinued to exist for another 6600 years after human arrival. Besides human impact the paper names the disappearance of grasslands as reason of extinction for the wild horses, and the advance of Nothofagus-trees for the Mylodon. Concluding, the extinction was probably caused as a combination of change in climate and vegetation as well as human arrival.

References

• Mercuri, A.M., Sadori, L. & Uzquiano Ollero, P. (2011) Mediterranean and north-African cultural adaptations to mid-Holocene environmental and climatic changes. The Holocene 21, 189-206. DOI: 10.1177/0959683610377532
• Villavicencio, N.A., Lindsey, E.L., Martin, F.M., Borrero, L.A., Moreno, P.I., Marshall, C.R. & Barnosky, A.D. (2016) Combination of humans, climate, and vegetation change triggered Late Quaternary megafauna extinction in the Última Esperanza region, southern Patagonia, Chile. Ecography 39, 125-140. DOI: 10.1111/ecog.01606
• Weijdema, F., Brinkkemper, O., Peeters, H. & van Geel, B. (2011) Early Neolithic human impact on the vegetation in a wetland environment in the Noordoostpolder, central Netherlands. Journal of Archaeology in the Low Countries 3, 31-46. Link