Impact of the Environment on Human Migration in Eurasia

This article presents the study of the famous Scythian monument Arzhan-2 discovered in Central Asia, Tuva Republic, in 2001. The main focus is the analyses of the different archaeological materials including typology, analogy, burial tradition etc to determine the chronological place of this monument in the nomadic world. The analyses of the artifacts is primarily concerned with the horse harness and its comparison with the materials from other monuments located in this region and the neighbouring territories. It is shown that in spite of the originality of the archaeological materials, they reflect the local culture and the earlier Scythian tradition. Thus the Arzhan-2 monument can be associated with the so-called aldy-bel culture dated to the 7^th-6^th centuries BC.

This paper is devoted to some problems of correlation between archaeological and radiocarbon dates in Scythian archaeology. Modern radiocarbon dates which are used to support an independent non-archaeological chronological system, in some cases provide evidence to narrow existing archaeological dates or show a good agreement with archaeological dates, and in other cases do not contradict them. The findings of chronological studies are clearer now: the accepted archaeological dates of early Scythian monuments (9^th-6^th centuries BC) are found as the later limits of their calibrated calendar age (¹⁴C ), whereas archaeological dates of classical antiquities (5^th-4^th centuries BC) are found in the earlier parts of their calibrated age range. For example, the “royal” Alexandropol barrow which was dated by archaeologists to the period 330-300 BC., has radiocarbon dates in the interval 2300-2080 BP, which corresponds to the 4^th-1^st century cal. BC.

This article is devoted to the periodic migrations of Asian nomads (Saka - Scythians, Hsiung-nu - Huns, Turks and Mongols), which can be traced from the beginning of the first millennium BC up to the 13th century AD according to archaeological and written sources. This correlates with periods of increasing humidity in the steppes during ancient times. While it is difficult to define the reasons for these migrations, it is possible, that climatic changes may have promoted them.

The article is devoted to the consideration of the initial stage of history of the Cimmerians, who were the first historically known nomadic people in Eastern Europe. The early 1^st millennium B.C. was characterized by the formative development of nomad pastoralism throughout the Eurasian steppes. During this time specialised nomadic economies developed based on the horse, so that most of the steppe regions were occupied by groups of nomads with their mobile way of life.

It is proposed that the appearance of the first nomadic horse-riding groups on the historical arena coincided with considerable changes of the environment in the Final Bronze Age. Worsening of climatic conditions had a negative effect on the Pontic steppes archaeological cultures with a mixed pastoral-agricultural economy. Steppe populations adjusted to the new conditions by adopting a new nomadic way of life as well as by developing new lands. The migrations of nomadic tribes from the steppe zone were not single events but rather a continuous process. Depopulation of the Pontic steppes was accompanied by intensive cultural and economic development of other territories, for example, the area north of the Caucasus Mountains, the Krim Peninsula, the regions of the middle Dnieper and also the Great Hungarian Plain. These new centers were located in areas of wetter climate and their situations allowed them to play an important role. Cimmerians played a vital part in the transmission of horse riding and in the development of a new bridle technique. Both innovations were to have a major impact on European history.

Interpretation of Radiocarbon dates can be rather complex. For example, variations in the natural ¹⁴C content cause the ¹⁴C clock rate to vary throughout time, causing the need for calibration of the ¹⁴C timescale. For the Scythian epoch, there is a problematic range in the ¹⁴C calibration curve. Radiocarbon dates of around 2450 BP always calibrate to ca. 800-400 BC, no matter the measurement precision.

In order to establish reliable chronologies, both state-of-the-art scientific and archaeological dating methods need to be employed. This includes high precision ¹⁴C dating and AMS, enabling dating of small samples such as from museum collections or other precious materials.

This article is devoted to the chronology of the occupation of the Southern steppe regions of Eurasia during the Holocene based on radiocarbon data. The steppe regions of the European and Asian steppe are compared. The main attention is given to the southern Siberia and Central Asia regions. These areas are typical inner regions not influenced by the Arctic and Atlantic Oceans. These locations and their environment impact on the development of ancient populations. On the contrary, for the European steppe the occupation of these regions in the Holocene began only in the Eneolithic epoch when the first ancient nomads penetrated from other territories and the more intensive occupation was seen during the Scythian time. Such phenomenon can be connected to the environmental changes which made the territories very attractive for a nomadic economy. The character of the calibration curve confirms the abruptness of the environment changes about 4600 BP and 2600 BP.

New ¹⁴C dates from the Minusinsk basin are presented. These dates have been calibrated together with earlier results. Different calibration methods have been used to study the chronology of the cultural developments in this region. Durations and timing of cultural developments in the Minusinsk basin from the Bronze Age to Scythian time are discussed.

The study is focused on the development of Eneolothic cultures on the background of environmental changes. Analyses of the geomorphologic location of the Yamnaya, Early Catacomb, North-Caucasus and Predkavkazskaya Catacomb cultures’ kurgans; the topography of burial grounds; climatic characteristics of 3,000 BC; ¹⁴C data; analyses of planigraphy of burial grounds and seasonality of graves enable us to develop a model of migration of pastoral culture populations within the study area, i.e. Kumo-Manich depression — the South Ergenui hills.

Gradually the climate deteriorated starting from 2,600-2,500 BC. Newcomers representing different cultures arrived from the South and maybe from the South-West. At first the population of the North Caucasus and Early Catacomb cultures exploited river valleys and watershed areas only during summer. Such a situation could have developed not only due to climatic changes but also thanks to consent of the Yamnaya culture bearers that were the first to use these areas. Appearance of “mixed” (multiritual) graves, multiritual funeral goods found in the graves of both autochthonous populations and newcomers allow us to suppose that this coexistence could be quite peaceful.

High-resolution radiocarbon dating of tree ring sequences provides a tool to overcome complications of the radiocarbon calibration curve. The time (2500 BP) when the Pazyryk culture thrived in the steppes of Siberia coincides with wiggles on the radiocarbon calibration curve. Results of radiocarbon dating of tree logs from the Pazyryk 2 and Ulandryk 4 tombs allow wiggle matching to the calibration curve and more precise dating of the time the kurgans were constructed. The ages of 300 and 311 BC for Pazyryk 2 and Ulandryk 4, respectively, support historical dating of the finds. Our chronology provides a piece in the puzzle of the expansion and the extension of the Scythian like cultures that dominated the steppes between 800-200 BC.

This paper considers modelling the ¹⁴C calibration curve using a variety of mathematical approaches. The main focus was the period of the 1^st millennium BC which is characterized by fluctuations of the ¹⁴C concentrations in the atmosphere. This results in a non-linear relationship between the radiocarbon age and calendar age. The present study focuses on the influence of the calibration curve on statistical inference concerning time intervals of archaeological cultures and phases. The result shows that for the first millennium BC the time intervals estimated on the basis of calibrated radiocarbon dates differ from the real intervals on the calendar timescale.

Stable isotope data (δ¹³C and δ¹⁵N) from bone collagen are dietary indicators. The isotopic fractionation of the carbon and nitrogen atoms in the amino acid chains from collagen reflects the isotopic fractionation in the food proteins. Stable isotope values make it possible to distinguish herbivores from carnivores, and to further distinguish between marine and terrestrial sources of food.

The OSL (optically stimulated luminescence) dating method exploits dosimetric properties of grains of minerals naturally occurring in sediments and man-made materials.

In archaeology the OSL method is used to date pottery and other heated materials (e.g., bricks, stones, earth) or sediments related to archaeological finds. The significant improvement of the OSL dating method in recent years makes it applicable to objects ranging in age from 0 to 150 000 years (in some cases to 300 000 or more) with a typical accuracy between 5 and 10%. When compared with the radiocarbon method it makes possible dating objects containing no organic matter or originating in periods for which the radiocarbon method is less accurate due to the shape or lack of the calibration curve.

This paper discusses the details of recent advances in the method and several examples of its application to material from archaeological excavations of Medieval to Palaeolithic sites.

The climate shift towards wetter conditions at the transition from Subboreal to Subatlantic in NW-Europe (ca 850 cal. yrs BC; caused by a decline of solar activity), is also evident in South Siberia. Areas that initially were hostile semi-deserts changed into attractive steppe landscapes with a high biomass production, and therefore high carrying capacity. We focus on south-central Siberia where an acceleration of cultural development and an increase in the density of nomadic Scythian populations took place shortly after 850 BC. We hypothesize a causal relationship between the Scythian expansion and migration, and the early Subatlantic shift towards increased humidity.

Numerous natural events documented in instrumental, historical and palaeoclimate records clearly indicate that large regions of the Earth have experienced occurrences of both slow and rapid climate change in the past. Various proxy records of long duration demonstrate distinct cyclicities from eleven years to hundreds of thousands years that have been attributed to external forcing. Until quite recently, palaeoclimatic research has tended to focus on evidence for longer-term climatic change, especially on glacial to interglacial timescales. The duration of these oscillations are varied with approximately a 1500-year periodicity and therefore not related to the Earth’ orbital variations around the Sun. After a number of cooling/warming episodes (Dansgaard-Oeschger cycles) there are terminal dramatic coolings called Heinrich events with temperature drops up to about 5°C before a major warming event. Such a cycle of warming and cooling is known as a Bond cycle with a mean duration of 2500 years. Both marine and continental sediment records confirm these rapid shifts.

The Holocene climate has also been a time of major climatic and environmental change, although in the current interglacial the Earth has remained at a rather steady climatic phase over the last 10,000 years in comparison with the preceding climatic phases of the last glacial cycle. From more recent studies on ice cores and marine sediments, there is evidence that the Holocene climate closely parallels that in the preceding last glacial cycle.

The analysis of amorphous organic residues from archaeological and ethnographic collections provides direct evidence for the use of natural materials, which can help enrich interpretations of past societies. The value of this approach is increasing, driven by advances in extraction and analytical techniques that permit the analysis of an ever-wider range of compounds. However these approaches have not yet been targeted towards toxins based upon natural plant based poisons and narcotics. This paper will present the outline of a chemical analysis based approach to identifying trace residues associated with hunting poisons and sacred hallucinogens as well as poisons of a purely harmful nature. The successful exploitation of potentially lethal natural toxins can be taken as representative of the great ingenuity shown in man’s adaptation to the environment.

The age and genesis of palaeosols buried under barrows and within floodplain sediments in the centre of the Russian Plain have been studied. Palaeosols formed in the time interval from 10000 to 3500 BP are represented by steppe Chernozems attesting to less humid climate, whereas palaeosols dating back to the past 3500 years are represented by Podzolic and Grey Forest soils (Luvisols) attesting to humid climate. The periods of northward migration of steppe tribes into the forest and forest-steppe zone took place in the Middle Bronze Age and in the epochs of Cimmerian and Sarmatian culture (4000-3500, 3000-2700 and 2000-1700 BP, respectively) corresponding to phases with dry climate and the development of steppe Chernozems. Several intervals with active alluviation and soil burial on the floodplains have been identified: 10500, 8000, 4500 and 500 BP, as well as about 6500 and 2500 BP. These intervals correspond to the periods with colder climate.

This paper deals with questions of paleogeography of the Black sea’s coast in the late Holocene on the basis of new data that include the lithology, palynology and geochronology of coastal marine, lagoon and deltaic sediments. The palynological results have shown that the warmest and dry conditions prevailed in the intervals 4100-3950, 3500-3300/3200, 2800-2400, 1650-1300 and 1000-900/800 yrs BP. The maxima of humidity for the studied period correspond with the chronological intervals 4500-4300 and 3950-3500 yrs BP, coinciding with the spread of forest communities. During an interval from 2500 up to 1500 BP (V centuries BC – V centuries AD) the dominance of the steppes formation was interrupted by phases of wetter climate which caused at first expansion of the wood-steppe vegetation, and then wide circulation of broad-leaved woods in the landscape. The palynological data have revealed a peculiarity that is connected to the economic activity of the local population.

The study of the coastal morphology and sediment structure have revealed traces of two transgressive phases in relative sea level change for the time under consideration the first relates to the interval 4.2-3.7 ka BP, the second - covers last 1.5 ka. Complex litho-facial, archaeological and geochronological data testify to the existence of a period of downturn in sea level, which covers an interval from the end of the 2^nd millenium BP up to the middle of the 1^st millenium AD.

Development of early human societies in Northern Eurasia depended on large-scale migrations combined with an indigenous evolution. The initial colonisation of Northern Eurasia by anatomically modern humans was proceeded by several migratory waves generally directed from the west to the east. Human displacements were triggered by environmental stress, and coincided with the coldest stages of the Last Ice Age (40,000-10,000 years before present, B.P.), when the conditions for livelihood were less severe in Eastern Europe and Siberia. The transition to Holocene at c. 10,000-9,000 yr. B.P. marked profound changes in the environment, with the rise of temperature by at least 6–12°C and increased humidity, leading to the extension of forests and the gradual establishment of present-day biogeographical zonality. Mesolithic lifestyle featured an increased sedentariness, combined with limited-scale seasonal transhumance. In the conditions of the northbound advancement of forests at 9000-7000 yr. B.P., a network of Mesolithic sites emerged north of the current arctic circle. This included the shelf of the Arctic Ocean, which became accessible, as the coastline was at least 150 km north of its present position. The ‘Neolithic revolution’ in Northern Eurasia occurred in the conditions of the thermal optimum, which became established at 8,000-7,000 yr. B.P., and led to the maximum expansion of forests, further increase of precipitation, the global rise of the sea level, and increased biological productivity of boreal landscapes.

The spread of Neolithic in northern Eurasia is seen as a combination of human migrations, cultural diffusion, with local inventions and adaptations, the intensity of which depended on the local natural and cultural environment. Based on the analysis of radiocarbon dates, archaeological and environmental evidence, we distinguished three basic processes in the Neolithisation of Northern Eurasia which are discussed in the article.

The migration of Scythians depended on climatic changes during the Bronze/Iron Age transition, which corresponds to Subboreal/Subatlantic climate periods. Data from oxbow lake sediments were used to distinguish climatic and environmental fluctuations. Climatic cooling started and humidity increased in the Late Subboreal. In the Bronze Age Subboreal draught farming spread and in the beginning of the Iron Age Subatlantic farming declined in East Europe. About 3500 years ago all the temperatures indices were about 1° higher and the precipitation was 50 mm more than nowadays. During the succeeding cooling at about 2500 years BP, the temperature was about 1° lower and the precipitation was a little greater in comparison with the modern indices. Precipitation decreased between the warming (3500 BP) and cooling (2500 BP). The biodiversity during the Bronze/Iron Age transition had an impact on the economy of Scythian cultures.

This study presents results of paleoclimatic reconstructions during the Holocene in Southern Siberia and Central Asia by means of a geochemical approach. For investigations the deposits of Kutudjekovo Lake (Minusinsk Depression), White Lake (Uyuk Depression), aeoline-paleosoil deposits from Arzhan -2 monument (Uyuk Depression) and loess-paleosoil deposits from Tepsey cross-section (Minusinsk Depression) were sampled. The determination of chemical composition was done by ICP-AES, SNC analysis and the Wesemael method. X-ray diffraction was applied for determination of clay compositions in the deposits. The granulometric composition was determined by means of the grain-size analysis. The correlation analysis and method of principal components was applied for processing. Radiocarbon dating and archaeological dating were applied for determination of age of the deposit. The results allow the possibility of reconstructing the climatic factors, affecting the sedimentary processes. The investigations showed the differences of local paleoclimatic conditions between Minusinsk and Uyuk depressions during the Holocene. The Uyuk Depression is characterized by warmer and drier paleoclimate, while the climate in the Minusinsk Depression was milder and damper. Most likely the landscape features of these depressions influenced the local climate. The synchronous climatic variations during the Holocene can be noted for both depressions. These developments have correlation with paleoclimatic events in the Mongolia region. On the whole, the climate in the period from 5000 years ago to 3000 years ago can be characterized as dry. About 3000 years ago in a cold climatic period the rise in humidity began. The humidity maximum was around 2500 years ago (1^st millennium BC). The period from 2500 to 1500 years ago was most humid and warm.

The differences in occupation of the depressions by ancient people, probably, were linked to their paleoclimatic peculiarities. The occupation processes in the Minusinsk depression were more intensive and more diverse, then in the Uyuk depression. The abrupt increase of humidity, which was dated to about 2500 years ago in both areas, probably, resulted in the appearance of numerous tribes of the Scythian culture over the whole territory.

A sharp increase in human population density and the same time fundamental changes in the location of settlement, moving away from earlier inhabited places points to significant changes in the environment. This period with a sharp decrease in anthropogenic indicators and poor records of slash and burn cultivation and field crop-growing is named “transition” period (Vasks et.al.1998) and indicates the lack of stable and continuous inhabitant sites. This phenomena can be explained by the small size of settlements at the Early Iron Age, expressed by a weak cultural layer and these could be defined as separate farmsteads. Modern farming practices, especially modern tillage, adversely affected the preservation of these settlements. Pollen and plant macrofossil analyses were used as tool to discover traces of human activity and environmental changes during the Early Metal Period.

The emergence and the cultural blooming of the Scythian cultures in the steppe of South Central Siberia occurred from the 9th century BC (ca. 2700 cal yr BP), much earlier than in the western part of Eurasia. To understand a possible climatic cause of this cultural phenomenon, we have studied sediment cores from the Kutuzhekovo Lake in the Minusinsk depression (Southern Siberia) and the White Lake in the Uyuk depression (Tuva, Central Asia). Both pollen records indicated an arid climate during the mid-Holocene up to ca. 4 kyr BP; increased moisture but still predominantly dry conditions at 4-3 kyr BP interval; a sudden change to more-humid-than-present climate in relatively cold conditions since ca. 3 kyr BP, and a return to drier/warmer climate after ca. 1.6 kyr BP. The reconstructed climate changes correlate well with cultural changes reported for both depressions. The scarcity of Mesolithic-Neolithic (10-5 ka) findings there is in good agreement with the mid-Holocene aridity, which did not provide favorable living conditions for the ancient tribes. By contrast, wet climate establishment since ca. 3 kyr BP corresponds to the Scythian cultures expansion to the Asian steppe which started in the 9^th century BC. The data obtained suggest the close relationship between climatic and cultural changes within these arid areas. We conjecture that increased effective moisture balance changed initially arid areas into attractive steppe with a higher biomass production which may have launched the cultural development and blooming of the Scythian cultures.

Frequency distributions of calibrated radiocarbon dates for some of the archaeological sites from the Holocene are compared with climatic records shown in frequency distributions of ¹⁴C data sets from speleothems, tufas and peat, laminae thickness, temperature and lake water changes for Poland, Central Europe. All archaeological and environmental events presented using the calendar time scale [BC/AD] are based on ¹⁴C dating performed in the Gliwice Radiocarbon Laboratory and come from “RoSE” database.

This paper presents the first osteological study and comparison of horse remains from the two famous Arzhan-1 and Arzhan-2 Scythian monument in Tuva. In spite of the fact that the horses from both monuments belong to the same breed groups, one can observe some differences in the sizes of the horses caused probably by differences in the local environmental conditions.