| چکیده انگلیسی مقاله |
Abstract
Throughout ancient periods, geographical conditions and natural factors have had a significant impact on the formation, prosperity, decline, and settlement patterns of ancient sites. This article examines the settlement of human groups in the northwestern part of the Central Plateau (Qazvin) and their settlement patterns from the beginning of the Late Neolithic period to the end of the Chalcolithic period, in light of geomorphological and altitudinal characteristics, drainage networks, and climatic changes. The results show that natural conditions have had a significant impact on the settlement pattern of ancient sites in the Qazvin sub-basin, as well as settlement discontinuities and continuities.
Keywords: Niche Construction, Settlement Pattern, Central Iranian Plateau, Qazvin sub-basin.
1. Introduction
The relationship between culture and the natural environment has been one of the oldest debates in archaeology and anthropology, consistently providing a source of discussion (Meggers, 1954). By observing the relationship between humans and the environment from the past to the present, it can be seen that this relationship has always been two-way. Although in the past, due to less knowledge and a more primitive level of technology, this influence was much greater than it is today, people have always been influenced by the environment and, in turn, have changed the environment (Haggett, translated by Shapour Goudarzinejad, 1384: 401).
This article examines the niche construction of human groups in the northwestern part of the Central Plateau (the Qazvin watershed sub-basin) and the displacement of settlements in relation to geomorphological, altitudinal, drainage network, and climatic changes during the Late Neolithic, Transitional Chalcolithic, and Chalcolithic periods. Niche construction refers to the activities, choices, and processes through which organisms define, select, modify, to some extent create their environments (Odling-Smee et al., 1996; Laland & O’Brien, 2012 & 2015; Laland et al., 2016). The shifting of settlements and the selection of new habitats throughout ancient periods in response to environmental and climatic changes can also be considered a form of niche construction, wherein humans shape the environment according to their needs and lifestyle. In their search for new habitats, communities were compelled to alter the environment around them. Early architecture and the beginning of agriculture are examples of such human interventions in the environment. While the relocation to new areas was a strategy for adapting to environmental changes, it was also itself a significant factor in causing environmental change.
2. Methodology
The study area of this research is the Qazvin sub-basin (Fig. 1). This sub-basin is itself a small part of the larger Namak Lake sub-basin. In terms of geomorphology, the Qazvin sub-basin is divided into three units: the northern unit (Alborz sub-unit), the interior basins and plains unit, and the central Iranian mountains unit (Alaei Taleghani, 1388). The most important landforms in the study area include mountains, alluvial fans, and alluvial plains.
The research began by delineating the Qazvin sub-basin using a 30-meter Digital Elevation Model (DEM) and ArcGIS. Based on the topography of the study area, the drainage network and all potential streams within the Qazvin sub-basin were extracted from the DEM. Subsequently, using ArcGIS, maps of distance from rivers and stream order were created, and analyzed in relation to the distribution, frequency, and density of sites. Afterward, geomorphological zones within the study area were identified and mapped using Google Earth satellite imagery, along with 1:50000 topographic maps and 1:100000 geological maps of the region. Subsequently, the location of ancient settlements was examined in relation to elevation, as well as the distribution of ancient sites across various geomorphological zones. In the next phase, the impacts of Holocene climate change on the settlement patterns of ancient sites over three specified periods were studied and analyzed.
3. Discussion
Analysis of settlement locations in relation to geomorphological features revealed that alluvial fans were the most densely occupied geomorphological landforms in this sub-basin during all three periods. Due to favorable geographic conditions such as gentle slopes, easy access to water resources, and the presence of fine-grained sediments, alluvial fans have historically been among the most preferred geomorphic landforms for settlement on the Iranian Plateau in general. The study of settlements in relation to altitude revealed that the highest density and percentage frequency of sites during the three periods under consideration were found in the 1000 to 1500-meter altitude range. During the Neolithic period, all ancient sites were located within this range, but during the Transitional Chalcolithic and Chalcolithic periods, in addition to this range, the distribution of sites extended to higher altitudes as well. A study of ancient sites in relation to their distance from rivers revealed that in the Qazvin sub-basin, the 0-500-meter range from the rivers was the most densely populated in all three studied periods. On the other hand, examining the location of these sites in relation to the stream order showed that in this sub-basin during the Neolithic period, most of the sites were located near third-order streams. In the Transitional Chalcolithic period, the concentration of sites was near to the first and second-order streams, while in the Chalcolithic period, first and third-order streams had the highest frequency of site concentration in their vicinity.
The relationship between settlement patterns and climate change was also examined. During the Neolithic period, most humans likely settled in low-lying areas with favorable environmental conditions for agricultural activities. During this period, all ancient sites were located in alluvial plains and alluvial fans. Most of the Neolithic archaeological sites in this study belong to the Late Neolithic period with an absolute and relative chronology ranging from 6000 to 5200 BCE (Fazeli Nashli et al., 1398: 48). Comparing this time frame with the climatic events of 9200 and 8200 BP indicates that the beginning of the cultural flourishing of the Neolithic period occurred after these two climatic events and coincided with more favorable climatic conditions.
Research conducted on the Transitional Chalcolithic period indicates an increase in aridity and dust during a portion of this timeframe. According to findings compiled by Sheikh Biklou Islam and colleagues (2023), this period is divided into three climatic phases: (a) 7300-7000 BP, the climate was temperate and humid; (b) 7000-6700 BPE, when humidity decreased; and (c) 6700-6300 BP, when the climate was relatively warm and humid, tending toward aridity towards the end. Our results show that settlement continuity persisted at several ancient sites, while settlement was disrupted at others. All settlements that continued to be occupied during the Neolithic and Transitional Chalcolithic periods were situated on alluvial fans at altitudes ranging between 1000 and 1500 meters. The increase in the frequency of settlements during the Transitional Chalcolithic period compared to the Neolithic period may be attributed to the favorable climatic conditions. Many climate proxies in the Middle East indicate dry climatic conditions during the Chalcolithic period ca. 6400-6000 BP. More than 30% of Chalcolithic sites are located in mountainous areas, and the aridity may have led to a change in subsistence patterns to pastoralism, towards higher altitudes. This indicates a type of ecological continuity and adaptation. On the other hand, a number of ancient sites were abandoned during the Chalcolithic period, mostly located between 500 and 1000 meters from watercourses, and often adjacent to lower-stream orders. As mentioned, during dry periods, due to less rainfall, the probability of watercourses drying up increased, and lower-order streams were often devoid of water flow during these periods. This could have been an aggravating factor in the difficult conditions for continued settlement during the Chalcolithic period in these sites.
4. Conclusion
The results of the study showed that natural conditions including geomorphology, altitude, drainage networks, and paleoclimate have had a significant impact on the pattern and the discontinuities and continuities of the settlement. |