- Email: [email protected]
Radiocarbon chronology of the Neolithic sites from the Boreal zone of European Russia and environmental changes based on the last proxy data
Quaternary International 203 (2009) 19–24
Contents lists available at ScienceDirect
Quaternary International journal homepage: www.elsevier.com/locate/quaint
Radiocarbon chronology of the Neolithic sites from the Boreal zone of European Russia and environmental changes based on the last proxy data G.I. Zaitseva a, *, V.A. Dergachev b a b
Institute for History of Material Culture of Russian Academy of Sciences, St. Petersburg, Russia Ioffe Physical-Technical Institute, St. Petersburg, Russia
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 24 July 2008
This article discusses the possible correlation of the Neolithisation of Western Europe with the environmental changes. The database of the Neolithic sites developed by the Radiocarbon Laboratory of the Institute for History of Material Culture has been used in the assessment of the frequency of radiocarbondated sites. Various isotopic methods have been used for the estimation of Holocene environmental changes. The comparative analysis reveals the correlation of maxima and minima in the distribution of radiocarbon-dated sites with the fluctuations of lake-level, solar and cosmic ray activities, oxygen isotopes and other environmental records. Ó 2008 Elsevier Ltd and INQUA. All rights reserved.
1. Introduction
2. Methods
Chronology of the Neolithic of North-Western Russia is now based on the solid evidence of radiocarbon dates. The radiocarbon dating of Mesolithic and Neolithic cultures started simultaneously with the introduction of this method into the practice of archaeological studies, with the amount of 14C dates increasing each year. It should be remarked that the concept of Neolithic as adopted in Russian Archaeology is substantially different from that adopted in the West. In the West the beginning of Neolithic is viewed as the spread of farming, while Russian Archaeology traditionally correlates it with the beginning of pottery-making. The aim of this paper is to systematically assess the possible correlation between the existing 14C the dates and the palaeoenvironmental evidence, as environmental conditions were very important for the economy and mode of life of early human groups. The first attempts at summarizing the radiocarbon dates of the Neolithic age were made by Dolukhanov and Timofeev (1972). Over the past 30 years the existing evidence regarding the age of ‘Forest’ Neolithic changed considerably. In the 1950–1970s, it was generally accepted that the beginning of ‘Forest’ Neolithic dates to the early 3rd millennium BC, at the present state of knowledge, this should be extended over to the 6th millennium BC. This became possible, due to numerous radiocarbon dates obtained from various areas of the East European Plain, and particularly, from the area of the Upper Volga Early Neolithic culture (Timofeev et al., 2004).
The compendium of 14C dates for the Neolithic sites of Northern Eurasia has been published in the volume of Archaeology of exUSSR on Neolithic (Oshibkina, 1996). This date-list has been considerably extended in later publications (Timofeev and Zaitseva, 1997; Zaitseva et al., 1997b; Kotova, 2002; Zaitseva and van Geel, 2004). Presently all existing dates on archaeological sites of exUSSR are included in the computerized database developed at the Radiocarbon Laboratory of the Institute for the History of Material Culture, Russian Academy of Sciences in St. Petersburg. This database presently includes more than 7000 radiocarbon measurements, 1070 among them being obtained for 340 Neolithic sites from the European part of exUSSR (Fig. 1; Timofeev et al., 2004). This computerized database can be used to plot the temporal distribution of the radiocarbon ages of Neolithic sites and thus identify the maxima and minima in the age frequencies. The amount of data forms but a small fraction of all known sites (no more than 5–10%), and therefore the question naturally arises whether the conclusions based on this limited sample might be deemed reliable. In this respect, one should note that the radiocarbon dates are now available for the majority of the key sites of fundamental importance for the study of basic archaeological cultures and their stages. This allows positive evaluation of the reliability of the conclusions. Investigations on the temporal distributions and frequencies of radiocarbon-dated sites based on the existing database have been conducted since 1997 (Zaitseva et al., 1997a, 1998), since then the amount of available 14C measurements has significantly increased. The temporal distribution of radiocarbon-dated sites of Neolithic age is shown in Fig. 2, where both maxima and minima are equally
* Corresponding author. E-mail addresses: [email protected] (G.I. Zaitseva), v.dergachev@pop. ioffe.rssi.ru (V.A. Dergachev). 1040-6182/$ – see front matter Ó 2008 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2008.04.012
20
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
curve, different parts of which are shown in Fig. 3. The early stage of the Holocene (9500–8500 cal BP) features irregular fluctuations of the 14C concentration. Irregular concentrations of 14C are also observed during the period of 6000–5500 cal BP. These data are in good agreement with palaeoclimate evidence discussed below. 3. Discussion Both very cold and very warm climate conditions are known to have had a significant impact on human populations. On the distribution curve of 14C dates for the Neolithic sites of Western Europe (Fig. 2) several maxima are observable, which are particularly articulated in the time span of about 9000, 7500, 5000 cal BP, and smaller ones 7500–5500 cal BP. These maxima obviously correspond to the increase in numbers of Neolithic sites. The aim is
Fig. 1. Map of the Neolithic sites of the Western Europe dated by
14
C.
discernable. In order to suggest a possible explanation, the observed fluctuations were interfaced with the existing data on environmental changes, based on the evidence of past climate and other elements of palaeoenvironment for the same chronological interval. Over the last decades, considerable evidence relative to the Holocene environmental changes has become available stemming from the analysis of the calibration curve (Bronk Ramsey, 1998, 2001). The intensity of radiocarbon content is indicative of several natural processes, such as solar activity, intensity of cosmic radiation, and possibly, the magnetic component, which had a direct bearing on past climates. Several peaks of high concentration of 14C have been identified for the period of the last 10,000 years. Fluctuations of 14C concentration ranging between w200 and w2000 years might be tentatively correlated with the changes in solar activity and climate (Dergachev and Veksler, 1991). Thus the periods of large-scale climatic mutations have been distinguished at the following levels: 400, 2700, 5000, 7200 and 9500 BP (Dergachev and Chistyakov, 1993). This can be seen in the calibration
Fig. 2. Distribution of the
14
C dates for the Neolithic sites of the Western Europe.
Fig. 3. The parts of the calibration curve related to the Neolithic period.
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
21
Fig. 4. Distribution of the dates of higher lake-level events reconstructed in the Jura mountains, the northern French Pre-Alps and the Swiss Plateau over the Holocene period (Magny, 2004). The vertical scales represent the number of dates for successive 50 years intervals between 12,250 and 0 cal yr BP.
to investigate whether these maxima might be correlated with environmental changes, acknowledgeable with the use of various proxy data. Notwithstanding large-scale current investigations aimed at obtaining reliable reconstruction of the past climate, understanding the pattern and rate of change of atmospheric circulation and its effect on climate and the hydrological sphere remains a challenging task. The present state of knowledge allows the possibility of identifying the main trends in the climate change in various parts of the world with the aid of a range of archives that include ice cores and corals. In many areas the evidence of sea and lake-level changes provide valuable evidence on the dynamics of marine and lacustrine basins, which were of vital importance for the livelihood of early human communities in densely populated areas of the world. During the Holocene changes in atmospheric circulation and the hydrological sphere as identified by direct observations as well as proxies, took place with various amplitude both in the high latitude, the tropics and the subtropics. Regarding the hydrological sphere, the most valuable data are obtained from the study of groundwater level, mountain glaciers, permafrost, soils, as well as lake and river systems, particularly in the wetland areas. Lake basins offer highly sensitive archives of environmental change, as lake-level records reflect past changes in the water budget, which is directly affected by climatic factors. The lake-level is largely controlled by evaporation and precipitation, both affected
by the climate. Magny (2004) has recently reconstructed the sealevel changes using a data set of 180 radiocarbon dates, tree-ring chronology, as well the dates and altitudinal position of archaeological Neolithic and Bronze age sites for 26 lakes in the French Jura and the Swiss Plateau. These dates form two separate groups, featuring the lower and higher level episodes. The high level episodes are characterized by the deposition mineral-rich sediments, whereas during the low level ones peat and/or organic detritus accumulated in the off-shore areas. According to a quantitative reconstruction, the higher level episodes correspond to an increased annual precipitation, decreased summer temperature and a shorter vegetation period. As Fig. 4 shows, the clusters of dates for higher level episodes correspond to those indicative of a cold Holocene climate. A ca. 2000-year quasi-periodicity in the frequency of cold climate fluctuations is clearly observable. Thus, the mid-European lake-level record testifies to a significant instability of the Holocene climate. The comparison with the temporal distribution of radiocarbon-dated sites of Neolithic age (Fig. 2) demonstrates a satisfactory correspondence of the maxima in both cases, particularly strong ones at 9500–7500 and 5800 cal BP and a lesser one between 4500 and 5500 cal BP. Noren et al. (2002) plotted a storm chronology, based on the evidence of terrigenous sedimentations in-wash layers, which reflect rainfall events of exceptional intensity/duration in the 13 lake drainage basins in the northeastern United States (Fig. 5). The frequency of storm-related floods in the northeastern United States
Fig. 5. Comparison of millennial-scale variability storminess (Noren et al., 2002) in the northeastern United States with other relevant climatic records: 1: Greenland ice core glaciochemical cold events (Mayewski et al., 2004). 2: Glacial expansions in the Alps (Hormes et al., 2001). 3: Periods of increased magnitude of the largest floods in the northcentral United States (Knox, 1999).
22
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
Fig. 6. Comparison of the Polar Circulation Index from GISP2 (Mayewski et al., 1997) with the mid-European lake-level fluctuations (Magny, 2004), with the ice-rafting debris events in the North Atlantic Ocean, and with the atmospheric residual 14C concentration (Stuiver et al., 1998) during the Holocene.
has varied in regular cycles during the past 13,000 years, with a characteristic millennial periodicity. This pattern is consistent with long-term changes in the average sign of the Arctic Oscillation. As was shown by Mayewski et al. (2004), atmospheric circulation modes controlled by sea-level pressure patterns, e.g. the El NinoSouthern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO), account for significant fractions of climatic variability on short timescales and may be modulated on longer timescales. Fig. 5 shows that maxima of terrigenous influx coincide with high storm frequencies and flooding episodes identifiable in other records from the North Atlantic area, and with cool
episodes in Greenland and Europe acknowledgeable in the glaciers records (Hormes et al., 2001) which correspond to the same time intervals as mentioned above: 9000 and 5800 cal BP. Fig. 6 shows a comparison of lake-level fluctuations in the French Jura (see Fig. 4), and the Swiss Plateau (Magny, 2004) with the Polar Circulation Index (PCI) (Mayewski et al., 1997) based on glaciochemical data of GISP2 ice cores (Greenland). PCI is a relative index of the average size and intensity of polar atmospheric circulation, which is increased during the colder periods. There is a satisfactory correlation between the major changes in the midEuropean lake-level, in the intensity of polar atmospheric
Fig. 7. (a) The reconstruction of solar irradiance forcing (grey line) based on the residual 14C concentration (Stuiver et al., 1998) for the last 10,000 years (left axis; in W/m2). The right axis gives the residual 14C record. The black line shows reconstruction of historic irradiance variations extended back in time to the year 1000 AD by the independent 10Be record (Lean et al., 1995; Bard et al., 2000; Weber et al., 2004). (b) Large-scale climate changes obtained on a basis of the record of the Polar Circulation Index from glaciochemical data in GISP2 ice cores (Mayewski et al., 1997) and episodes of distinct glacier advances: European, North American, and Southern Hemisphere (Denton and Karle´n, 1973), and central Asia (Haug et al., 2003). The lowest solar irradiance levels fall on the coldest intervals.
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
circulation from the GISP2 record and in the atmospheric 14C residual concentration (D14C) (Fig. 6) based on tree-ring records (Stuiver et al., 1998), which may be considered as a proxy record for past changes in solar activity. Vasiliev and Dergachev (2002) have carried out a power spectrum, time-spectrum and bispectrum analyses for the long-term series of the radiocarbon concentrations deduced from the measurements of the radiocarbon content in the tree rings for the last 8000 years. These analyses revealed a periodicity of w2400 years. The peaks of ice-rafting debris (IRD) from the cores in the North Atlantic (Fig. 6) are of a more complex character. Bond et al. (1997) established the IRD events to alternate over the entire Holocene period with a periodicity of ca. 1500-years. However, the higher lake-level episodes coinciding with D14C and PCI maxima, including the most part of IRD events equally display a periodicity of ca.2400-year. Thus, the data outlined in Fig. 6 demonstrate that at least largescale cold events acknowledged in various palaeoclimatic archives from the Northern Hemisphere show a close coincidence in time. The close correlation between proxy data and the variations in atmospheric 14C concentration shown on Fig. 6 suggests the solar activity to be a key factor in the variability of the Holocene climate over the North Atlantic area. Climate changes induced by the variations in solar activity might have had a significant impact on the type of settlement and culture of the Neolithic and more recent human groups. At present proxy evidence of Holocene cold episodes are available for Europe, Greenland, North America, and the Southern Hemisphere. Mayewski et al. (2004) have currently analyzed 50 globally distributed high-resolution climate proxy records. The writers distinguished six periods of major rapid climate change: 9000–8000, 6000–5000, 4200–3800, 3500–2500, 1200–1000, and 600–150 cal BP which display a good correspondence with the temporal distribution of radiocarbon-dated archaeological sites (Fig. 2). Significantly, the frequency of these rapid climate changes reveals a regular quasi-periodic pattern. In most cases, the events of rapid climate change are characterized by the polar cooling, tropical aridity, and major atmospheric circulation restructuring. However, the most recent episode, of polar cooling (600– 150 cal year BP) was accompanied by increased moisture in some tropical areas. It was also established that the major climate changes have significant impacts on ecosystems and human societies, and that several intervals coincide with major disruptions of civilization, thus illustrating the human significance of Holocene climate variability. Although the causes of global climate changes acknowledgeable in proxy records are not fully understood, they may be caused by changes in the energy output of the Sun and modifications in the internal variability of the ocean–atmosphere system. Simulations of time-dependent climate response to solar radiative forcing for the last 500–1000 years indicate that solar forcing indeed prevails over internal variability in generating temperature variations at decadal and longer timescales as well as large spatial scales (e.g. Rind et al., 1999). Exact measurements of the concentration of 14C in year-byyear tree rings allow tracing continuous long-term changes in the level of solar activity over the last 10,000 years. The analysis of the 10 Be level in Greenland’s ice cores (Finkel and Nishizumi, 1997) constitutes an independent check of fluctuations of solar activity, showing that the temporal trajectories of concentrations of both cosmogenic isotopes are similar. As changes in the level of 14C and 10 Be are subject to various perturbations in exchange reservoirs, these common features allow one to draw a conclusion that the probable cause of these features resides in the Sun. As follows from direct measurements of solar irradiance over more than 25 years (Fro¨hlich, 2000), solar irradiance changes in time in phase with solar sunspots. It allows us to reconstruct both solar activity and solar irradiance from cosmogenic isotopes.
23
The reconstruction of solar irradiance derived from the change of 14C concentration covering 10,000 years is shown in Fig. 7a (Weber et al., 2004). The lowest levels of solar irradiance and the highest levels of 14C concentration reoccur with the frequency of w2400 years (shown by arrows in Fig. 7a). Numerous studies provide evidence of solar irradiance forcing in proxy data. Considering the effect of the solar forcing on the variability of climate (Fig. 7b) one may note that the low solar irradiance levels coincide with the cold intervals, essentially similar to the Little Ice Age. Significantly, the Greenland ice cores contain sea-salt and dust deposition levels, indicative of large-scale changes occurring with a quasi-2500-year frequency (O’Brien et al., 1995), and consistent with world-wide expansions of mountain glaciers (Fig. 7b). 4. Conclusions The investigations based on the analysis of the distribution of the 14C dates for the Neolithic sites in Western Europe reveal fluctuations in the distribution of radiocarbon-dated sites, which are apparently coeval with environmental changes. This is further substantiated by newly available proxy data with the use of cosmogenic isotopes, lake-levels, ice-rafting and other records. Acknowledgements This research was supported by INTAS, project No. 03-51-4261. References Bard, E., Raisbeck, G., Yiou, F., Jouzel, J., 2000. Solar irradiance during the last 1200 years based on cosmogenic nuclides. Tellus 52B, 985–992. Bond, G., Showers, W., Cheseby, M., Lotti, R., Almasi, P., deMenocal, P., Priore, P., Cullen, H., Hadjas, I., Bonani, G., 1997. A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates. Science 278, 1257–1266. Bronk Ramsey, C., 1998. Probability and dating. Radiocarbon 40, 461–474. Bronk Ramsey, C., 2001. Development of the Radiocarbon Program OxCal. Radiocarbon 43 (2A), 355–363. Denton, G.H., Karle´n, W., 1973. Holocene climatic variations: their pattern and possible cause. Quaternary Research 3, 155–205. Dergachev, V.A., Veksler, V.S., 1991. The application of radiocarbon method to study the past environment. Monograph, Leningrad. 258 p. (in Russian). Dergachev, V.A., Chistyakov, V.F., 1993. 210- and 2400 year solar cycles and the climatic changes. In: Solar Cycle. PhTI RAS, Saint-Petersburg, pp. 112–131 (in Russian). Dolukhanov, P.M., Timofeev, V.I., 1972. The absolute chronology of the Neolithic of Eurasia on the radiocarbon methods. In: Problems of the Absolute Chronology in Archaeology, Moscow, pp. 28–78 (in Russian). Finkel, R.C., Nishizumi, K., 1997. Beryllium 10 concentrations in the Greenland Ice Sheet Project 2 ice core from 3–40 ka. Journal of Geophysical Research 102, 26699–26706. Fro¨hlich, C., 2000. Observations of irradiance variations. Space Science Review 94, 15–24. Haug, G.H., Gunther, D., Peterson, L.C., Sigman, D.M., Hughen, K.A., Aeschlimann, B., 2003. Climate and the collapse of Maya civilization. Science 299, 1731–1735. Hormes, A., Mu¨ller, B.U., Schlu¨chter, C., 2001. The Alps with little ice: evidence for eight Holocene phases of reduced glacier extent in the central Swiss Alps. Holocene 11, 255–265. Knox, J.C., 1999. Sensitivity of modern and Holocene floods to climate change. Quaternary Science Review 19, 439–457. Kotova, N.S., 2002. The Neolithization of Ukraine. Shlyakh, Lugansk, 266 p. (in Russian). Lean, J., Beer, J., Bradley, R., 1995. Reconstruction of solar irradiance since 1610: implications for climate change. Geophysical Research Letters 19, 3195–3198. Magny, M., 2004. Holocene climate variability as reflected by mid-European lakelevel fluctuations and its probable impact on prehistoric human settlements. Quaternary International 113, 65–79. Mayewski, P.A., Meeker, L.D., Twickler, M.S., Whitlow, S., Yang, Q., Lyons, W.B., Prentice, M., 1997. Major features and forcing of high-latitude northern hemisphere atmospheric circulation using a 110,000-year long glaciochemical series. Journal of Geophysical Research 102, 26345–26366. Mayewski, P.A., Rohling, E., Stager, C., Karle´n, W., Maasch, K., Meeker, L.D., Meyerson, E., Gasse, F., van Kreveld, S., Holmgren, K., Lee-Thorp, J., Rosqvist, G., Rack, F., Staubwasser, M., Schneider, R.R., Steig, E., 2004. Holocene climate variability. Quaternary Research 62, 243–255. Noren, A.J., Bierman, P.R., Steig, E.J., Lini, A., Southon, J.A., 2002. Millennial-scale storminess variability in the northeastern United States during the Holocene. Nature 419, 821–824.
24
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
O’Brien, S.R., Mayewski, P.A., Meeker, L.D., Meese, D.A., Twickler, M.S., Whitlow, S.I., 1995. Complexity of Holocene climate as reconstructed from a Greenland ice core. Science 270, 1962–1964. Oshibkina, S.V. (Ed.), 1996. The Neolithic of the Northern Eurasia. Nauka, Moscow, pp. 231–248 (in Russian). Rind, D., Lean, J., Healy, R., 1999. Simulated time-dependent climate response to solar radiative forcing since 1600. Journal of Geophysical Research 104, 1973–1990. Stuiver, M., Reimer, P.J., Bard, E., Beck, J.W., Burr, G.S., Hughen, K.A., Kromer, B., McCormac, G., van der Plicht, J., Spurk, M., 1998. Intcal98 radiocarbon age calibration 24,000–0 cal BP. Radiocarbon 40 (3), 1041–1083. Timofeev, V.I., Zaitseva, G.I., Dolukhanov, P.M., Shukurov, A.M., 2004. Radiocarbon Chronology of the Neolithic of the Northern Eurasia. Thesa, St. Petersburg,157 p. (in Russian). Timofeev, V.I., Zaitseva, G.I., 1997. Some aspects on radiocarbon chronology of the Neolithic cultures in the Forest zone of the European part of Russia. In: Proceedings of the VII Nordic Conference on the Application of Scientific Methods in Archaeology. ISKOS, 11, pp. 15–23. Vasiliev, S.S., Dergachev, V.A., 2002. The w2400-year cycle in atmospheric radiocarbon concentration: bispectrum of 14C data over the last 8000 years. Annales Geophysicae 20, 115–120.
Weber, S.L., Crowley, J., van der Schrier, G., 2004. Solar irradiance forcing of centennial climate variability during the Holocene. Climate Dynamics 22, 539–553. Zaitseva, G.I., Timofeev, V.I., Dergachev, V.A., Sementsov, A.A., 1997a. Some aspects on the distribution on radiocarbon dates form the Mesolithic and Neolithic of European Russia. In: Proceedings of the VII Nordic Conference on the Application of Scientific Methods in Archaeology. ISKOS, 11, pp. 33–39. Zaitseva, G.I., Dergachev, V.A., Timofeev, V.I., Sementsov, A.A., 1997b. Radiocarbon chronology of the archaeological sites for European Russia and natural changes: the database investigation. Radiocarbon and Archaeology 2, 4–12. St. Petersburg (in Russian). Zaitseva, G.I., Dergachev, V.A., Timofeev, V.I., Sementsov, A.A., 1998. 14C chronology of archaeological sites in European Russia and changes in environmental processes: a database investigation. Radiocarbon 40 (2), 759–767. Zaitseva, G.I., van Geel, B., 2004. The occupation history of the southern Eurasian steppe during the Holocene: chronology, the calibration curve and methodological problems of the Scythian chronology. In: Impact of Environment on Human Migration. NATO Series, vol. 42. Kluwer Academic Publishers, pp. 63–83.
Contents lists available at ScienceDirect
Quaternary International journal homepage: www.elsevier.com/locate/quaint
Radiocarbon chronology of the Neolithic sites from the Boreal zone of European Russia and environmental changes based on the last proxy data G.I. Zaitseva a, *, V.A. Dergachev b a b
Institute for History of Material Culture of Russian Academy of Sciences, St. Petersburg, Russia Ioffe Physical-Technical Institute, St. Petersburg, Russia
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 24 July 2008
This article discusses the possible correlation of the Neolithisation of Western Europe with the environmental changes. The database of the Neolithic sites developed by the Radiocarbon Laboratory of the Institute for History of Material Culture has been used in the assessment of the frequency of radiocarbondated sites. Various isotopic methods have been used for the estimation of Holocene environmental changes. The comparative analysis reveals the correlation of maxima and minima in the distribution of radiocarbon-dated sites with the fluctuations of lake-level, solar and cosmic ray activities, oxygen isotopes and other environmental records. Ó 2008 Elsevier Ltd and INQUA. All rights reserved.
1. Introduction
2. Methods
Chronology of the Neolithic of North-Western Russia is now based on the solid evidence of radiocarbon dates. The radiocarbon dating of Mesolithic and Neolithic cultures started simultaneously with the introduction of this method into the practice of archaeological studies, with the amount of 14C dates increasing each year. It should be remarked that the concept of Neolithic as adopted in Russian Archaeology is substantially different from that adopted in the West. In the West the beginning of Neolithic is viewed as the spread of farming, while Russian Archaeology traditionally correlates it with the beginning of pottery-making. The aim of this paper is to systematically assess the possible correlation between the existing 14C the dates and the palaeoenvironmental evidence, as environmental conditions were very important for the economy and mode of life of early human groups. The first attempts at summarizing the radiocarbon dates of the Neolithic age were made by Dolukhanov and Timofeev (1972). Over the past 30 years the existing evidence regarding the age of ‘Forest’ Neolithic changed considerably. In the 1950–1970s, it was generally accepted that the beginning of ‘Forest’ Neolithic dates to the early 3rd millennium BC, at the present state of knowledge, this should be extended over to the 6th millennium BC. This became possible, due to numerous radiocarbon dates obtained from various areas of the East European Plain, and particularly, from the area of the Upper Volga Early Neolithic culture (Timofeev et al., 2004).
The compendium of 14C dates for the Neolithic sites of Northern Eurasia has been published in the volume of Archaeology of exUSSR on Neolithic (Oshibkina, 1996). This date-list has been considerably extended in later publications (Timofeev and Zaitseva, 1997; Zaitseva et al., 1997b; Kotova, 2002; Zaitseva and van Geel, 2004). Presently all existing dates on archaeological sites of exUSSR are included in the computerized database developed at the Radiocarbon Laboratory of the Institute for the History of Material Culture, Russian Academy of Sciences in St. Petersburg. This database presently includes more than 7000 radiocarbon measurements, 1070 among them being obtained for 340 Neolithic sites from the European part of exUSSR (Fig. 1; Timofeev et al., 2004). This computerized database can be used to plot the temporal distribution of the radiocarbon ages of Neolithic sites and thus identify the maxima and minima in the age frequencies. The amount of data forms but a small fraction of all known sites (no more than 5–10%), and therefore the question naturally arises whether the conclusions based on this limited sample might be deemed reliable. In this respect, one should note that the radiocarbon dates are now available for the majority of the key sites of fundamental importance for the study of basic archaeological cultures and their stages. This allows positive evaluation of the reliability of the conclusions. Investigations on the temporal distributions and frequencies of radiocarbon-dated sites based on the existing database have been conducted since 1997 (Zaitseva et al., 1997a, 1998), since then the amount of available 14C measurements has significantly increased. The temporal distribution of radiocarbon-dated sites of Neolithic age is shown in Fig. 2, where both maxima and minima are equally
* Corresponding author. E-mail addresses: [email protected] (G.I. Zaitseva), v.dergachev@pop. ioffe.rssi.ru (V.A. Dergachev). 1040-6182/$ – see front matter Ó 2008 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2008.04.012
20
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
curve, different parts of which are shown in Fig. 3. The early stage of the Holocene (9500–8500 cal BP) features irregular fluctuations of the 14C concentration. Irregular concentrations of 14C are also observed during the period of 6000–5500 cal BP. These data are in good agreement with palaeoclimate evidence discussed below. 3. Discussion Both very cold and very warm climate conditions are known to have had a significant impact on human populations. On the distribution curve of 14C dates for the Neolithic sites of Western Europe (Fig. 2) several maxima are observable, which are particularly articulated in the time span of about 9000, 7500, 5000 cal BP, and smaller ones 7500–5500 cal BP. These maxima obviously correspond to the increase in numbers of Neolithic sites. The aim is
Fig. 1. Map of the Neolithic sites of the Western Europe dated by
14
C.
discernable. In order to suggest a possible explanation, the observed fluctuations were interfaced with the existing data on environmental changes, based on the evidence of past climate and other elements of palaeoenvironment for the same chronological interval. Over the last decades, considerable evidence relative to the Holocene environmental changes has become available stemming from the analysis of the calibration curve (Bronk Ramsey, 1998, 2001). The intensity of radiocarbon content is indicative of several natural processes, such as solar activity, intensity of cosmic radiation, and possibly, the magnetic component, which had a direct bearing on past climates. Several peaks of high concentration of 14C have been identified for the period of the last 10,000 years. Fluctuations of 14C concentration ranging between w200 and w2000 years might be tentatively correlated with the changes in solar activity and climate (Dergachev and Veksler, 1991). Thus the periods of large-scale climatic mutations have been distinguished at the following levels: 400, 2700, 5000, 7200 and 9500 BP (Dergachev and Chistyakov, 1993). This can be seen in the calibration
Fig. 2. Distribution of the
14
C dates for the Neolithic sites of the Western Europe.
Fig. 3. The parts of the calibration curve related to the Neolithic period.
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
21
Fig. 4. Distribution of the dates of higher lake-level events reconstructed in the Jura mountains, the northern French Pre-Alps and the Swiss Plateau over the Holocene period (Magny, 2004). The vertical scales represent the number of dates for successive 50 years intervals between 12,250 and 0 cal yr BP.
to investigate whether these maxima might be correlated with environmental changes, acknowledgeable with the use of various proxy data. Notwithstanding large-scale current investigations aimed at obtaining reliable reconstruction of the past climate, understanding the pattern and rate of change of atmospheric circulation and its effect on climate and the hydrological sphere remains a challenging task. The present state of knowledge allows the possibility of identifying the main trends in the climate change in various parts of the world with the aid of a range of archives that include ice cores and corals. In many areas the evidence of sea and lake-level changes provide valuable evidence on the dynamics of marine and lacustrine basins, which were of vital importance for the livelihood of early human communities in densely populated areas of the world. During the Holocene changes in atmospheric circulation and the hydrological sphere as identified by direct observations as well as proxies, took place with various amplitude both in the high latitude, the tropics and the subtropics. Regarding the hydrological sphere, the most valuable data are obtained from the study of groundwater level, mountain glaciers, permafrost, soils, as well as lake and river systems, particularly in the wetland areas. Lake basins offer highly sensitive archives of environmental change, as lake-level records reflect past changes in the water budget, which is directly affected by climatic factors. The lake-level is largely controlled by evaporation and precipitation, both affected
by the climate. Magny (2004) has recently reconstructed the sealevel changes using a data set of 180 radiocarbon dates, tree-ring chronology, as well the dates and altitudinal position of archaeological Neolithic and Bronze age sites for 26 lakes in the French Jura and the Swiss Plateau. These dates form two separate groups, featuring the lower and higher level episodes. The high level episodes are characterized by the deposition mineral-rich sediments, whereas during the low level ones peat and/or organic detritus accumulated in the off-shore areas. According to a quantitative reconstruction, the higher level episodes correspond to an increased annual precipitation, decreased summer temperature and a shorter vegetation period. As Fig. 4 shows, the clusters of dates for higher level episodes correspond to those indicative of a cold Holocene climate. A ca. 2000-year quasi-periodicity in the frequency of cold climate fluctuations is clearly observable. Thus, the mid-European lake-level record testifies to a significant instability of the Holocene climate. The comparison with the temporal distribution of radiocarbon-dated sites of Neolithic age (Fig. 2) demonstrates a satisfactory correspondence of the maxima in both cases, particularly strong ones at 9500–7500 and 5800 cal BP and a lesser one between 4500 and 5500 cal BP. Noren et al. (2002) plotted a storm chronology, based on the evidence of terrigenous sedimentations in-wash layers, which reflect rainfall events of exceptional intensity/duration in the 13 lake drainage basins in the northeastern United States (Fig. 5). The frequency of storm-related floods in the northeastern United States
Fig. 5. Comparison of millennial-scale variability storminess (Noren et al., 2002) in the northeastern United States with other relevant climatic records: 1: Greenland ice core glaciochemical cold events (Mayewski et al., 2004). 2: Glacial expansions in the Alps (Hormes et al., 2001). 3: Periods of increased magnitude of the largest floods in the northcentral United States (Knox, 1999).
22
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
Fig. 6. Comparison of the Polar Circulation Index from GISP2 (Mayewski et al., 1997) with the mid-European lake-level fluctuations (Magny, 2004), with the ice-rafting debris events in the North Atlantic Ocean, and with the atmospheric residual 14C concentration (Stuiver et al., 1998) during the Holocene.
has varied in regular cycles during the past 13,000 years, with a characteristic millennial periodicity. This pattern is consistent with long-term changes in the average sign of the Arctic Oscillation. As was shown by Mayewski et al. (2004), atmospheric circulation modes controlled by sea-level pressure patterns, e.g. the El NinoSouthern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO), account for significant fractions of climatic variability on short timescales and may be modulated on longer timescales. Fig. 5 shows that maxima of terrigenous influx coincide with high storm frequencies and flooding episodes identifiable in other records from the North Atlantic area, and with cool
episodes in Greenland and Europe acknowledgeable in the glaciers records (Hormes et al., 2001) which correspond to the same time intervals as mentioned above: 9000 and 5800 cal BP. Fig. 6 shows a comparison of lake-level fluctuations in the French Jura (see Fig. 4), and the Swiss Plateau (Magny, 2004) with the Polar Circulation Index (PCI) (Mayewski et al., 1997) based on glaciochemical data of GISP2 ice cores (Greenland). PCI is a relative index of the average size and intensity of polar atmospheric circulation, which is increased during the colder periods. There is a satisfactory correlation between the major changes in the midEuropean lake-level, in the intensity of polar atmospheric
Fig. 7. (a) The reconstruction of solar irradiance forcing (grey line) based on the residual 14C concentration (Stuiver et al., 1998) for the last 10,000 years (left axis; in W/m2). The right axis gives the residual 14C record. The black line shows reconstruction of historic irradiance variations extended back in time to the year 1000 AD by the independent 10Be record (Lean et al., 1995; Bard et al., 2000; Weber et al., 2004). (b) Large-scale climate changes obtained on a basis of the record of the Polar Circulation Index from glaciochemical data in GISP2 ice cores (Mayewski et al., 1997) and episodes of distinct glacier advances: European, North American, and Southern Hemisphere (Denton and Karle´n, 1973), and central Asia (Haug et al., 2003). The lowest solar irradiance levels fall on the coldest intervals.
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
circulation from the GISP2 record and in the atmospheric 14C residual concentration (D14C) (Fig. 6) based on tree-ring records (Stuiver et al., 1998), which may be considered as a proxy record for past changes in solar activity. Vasiliev and Dergachev (2002) have carried out a power spectrum, time-spectrum and bispectrum analyses for the long-term series of the radiocarbon concentrations deduced from the measurements of the radiocarbon content in the tree rings for the last 8000 years. These analyses revealed a periodicity of w2400 years. The peaks of ice-rafting debris (IRD) from the cores in the North Atlantic (Fig. 6) are of a more complex character. Bond et al. (1997) established the IRD events to alternate over the entire Holocene period with a periodicity of ca. 1500-years. However, the higher lake-level episodes coinciding with D14C and PCI maxima, including the most part of IRD events equally display a periodicity of ca.2400-year. Thus, the data outlined in Fig. 6 demonstrate that at least largescale cold events acknowledged in various palaeoclimatic archives from the Northern Hemisphere show a close coincidence in time. The close correlation between proxy data and the variations in atmospheric 14C concentration shown on Fig. 6 suggests the solar activity to be a key factor in the variability of the Holocene climate over the North Atlantic area. Climate changes induced by the variations in solar activity might have had a significant impact on the type of settlement and culture of the Neolithic and more recent human groups. At present proxy evidence of Holocene cold episodes are available for Europe, Greenland, North America, and the Southern Hemisphere. Mayewski et al. (2004) have currently analyzed 50 globally distributed high-resolution climate proxy records. The writers distinguished six periods of major rapid climate change: 9000–8000, 6000–5000, 4200–3800, 3500–2500, 1200–1000, and 600–150 cal BP which display a good correspondence with the temporal distribution of radiocarbon-dated archaeological sites (Fig. 2). Significantly, the frequency of these rapid climate changes reveals a regular quasi-periodic pattern. In most cases, the events of rapid climate change are characterized by the polar cooling, tropical aridity, and major atmospheric circulation restructuring. However, the most recent episode, of polar cooling (600– 150 cal year BP) was accompanied by increased moisture in some tropical areas. It was also established that the major climate changes have significant impacts on ecosystems and human societies, and that several intervals coincide with major disruptions of civilization, thus illustrating the human significance of Holocene climate variability. Although the causes of global climate changes acknowledgeable in proxy records are not fully understood, they may be caused by changes in the energy output of the Sun and modifications in the internal variability of the ocean–atmosphere system. Simulations of time-dependent climate response to solar radiative forcing for the last 500–1000 years indicate that solar forcing indeed prevails over internal variability in generating temperature variations at decadal and longer timescales as well as large spatial scales (e.g. Rind et al., 1999). Exact measurements of the concentration of 14C in year-byyear tree rings allow tracing continuous long-term changes in the level of solar activity over the last 10,000 years. The analysis of the 10 Be level in Greenland’s ice cores (Finkel and Nishizumi, 1997) constitutes an independent check of fluctuations of solar activity, showing that the temporal trajectories of concentrations of both cosmogenic isotopes are similar. As changes in the level of 14C and 10 Be are subject to various perturbations in exchange reservoirs, these common features allow one to draw a conclusion that the probable cause of these features resides in the Sun. As follows from direct measurements of solar irradiance over more than 25 years (Fro¨hlich, 2000), solar irradiance changes in time in phase with solar sunspots. It allows us to reconstruct both solar activity and solar irradiance from cosmogenic isotopes.
23
The reconstruction of solar irradiance derived from the change of 14C concentration covering 10,000 years is shown in Fig. 7a (Weber et al., 2004). The lowest levels of solar irradiance and the highest levels of 14C concentration reoccur with the frequency of w2400 years (shown by arrows in Fig. 7a). Numerous studies provide evidence of solar irradiance forcing in proxy data. Considering the effect of the solar forcing on the variability of climate (Fig. 7b) one may note that the low solar irradiance levels coincide with the cold intervals, essentially similar to the Little Ice Age. Significantly, the Greenland ice cores contain sea-salt and dust deposition levels, indicative of large-scale changes occurring with a quasi-2500-year frequency (O’Brien et al., 1995), and consistent with world-wide expansions of mountain glaciers (Fig. 7b). 4. Conclusions The investigations based on the analysis of the distribution of the 14C dates for the Neolithic sites in Western Europe reveal fluctuations in the distribution of radiocarbon-dated sites, which are apparently coeval with environmental changes. This is further substantiated by newly available proxy data with the use of cosmogenic isotopes, lake-levels, ice-rafting and other records. Acknowledgements This research was supported by INTAS, project No. 03-51-4261. References Bard, E., Raisbeck, G., Yiou, F., Jouzel, J., 2000. Solar irradiance during the last 1200 years based on cosmogenic nuclides. Tellus 52B, 985–992. Bond, G., Showers, W., Cheseby, M., Lotti, R., Almasi, P., deMenocal, P., Priore, P., Cullen, H., Hadjas, I., Bonani, G., 1997. A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates. Science 278, 1257–1266. Bronk Ramsey, C., 1998. Probability and dating. Radiocarbon 40, 461–474. Bronk Ramsey, C., 2001. Development of the Radiocarbon Program OxCal. Radiocarbon 43 (2A), 355–363. Denton, G.H., Karle´n, W., 1973. Holocene climatic variations: their pattern and possible cause. Quaternary Research 3, 155–205. Dergachev, V.A., Veksler, V.S., 1991. The application of radiocarbon method to study the past environment. Monograph, Leningrad. 258 p. (in Russian). Dergachev, V.A., Chistyakov, V.F., 1993. 210- and 2400 year solar cycles and the climatic changes. In: Solar Cycle. PhTI RAS, Saint-Petersburg, pp. 112–131 (in Russian). Dolukhanov, P.M., Timofeev, V.I., 1972. The absolute chronology of the Neolithic of Eurasia on the radiocarbon methods. In: Problems of the Absolute Chronology in Archaeology, Moscow, pp. 28–78 (in Russian). Finkel, R.C., Nishizumi, K., 1997. Beryllium 10 concentrations in the Greenland Ice Sheet Project 2 ice core from 3–40 ka. Journal of Geophysical Research 102, 26699–26706. Fro¨hlich, C., 2000. Observations of irradiance variations. Space Science Review 94, 15–24. Haug, G.H., Gunther, D., Peterson, L.C., Sigman, D.M., Hughen, K.A., Aeschlimann, B., 2003. Climate and the collapse of Maya civilization. Science 299, 1731–1735. Hormes, A., Mu¨ller, B.U., Schlu¨chter, C., 2001. The Alps with little ice: evidence for eight Holocene phases of reduced glacier extent in the central Swiss Alps. Holocene 11, 255–265. Knox, J.C., 1999. Sensitivity of modern and Holocene floods to climate change. Quaternary Science Review 19, 439–457. Kotova, N.S., 2002. The Neolithization of Ukraine. Shlyakh, Lugansk, 266 p. (in Russian). Lean, J., Beer, J., Bradley, R., 1995. Reconstruction of solar irradiance since 1610: implications for climate change. Geophysical Research Letters 19, 3195–3198. Magny, M., 2004. Holocene climate variability as reflected by mid-European lakelevel fluctuations and its probable impact on prehistoric human settlements. Quaternary International 113, 65–79. Mayewski, P.A., Meeker, L.D., Twickler, M.S., Whitlow, S., Yang, Q., Lyons, W.B., Prentice, M., 1997. Major features and forcing of high-latitude northern hemisphere atmospheric circulation using a 110,000-year long glaciochemical series. Journal of Geophysical Research 102, 26345–26366. Mayewski, P.A., Rohling, E., Stager, C., Karle´n, W., Maasch, K., Meeker, L.D., Meyerson, E., Gasse, F., van Kreveld, S., Holmgren, K., Lee-Thorp, J., Rosqvist, G., Rack, F., Staubwasser, M., Schneider, R.R., Steig, E., 2004. Holocene climate variability. Quaternary Research 62, 243–255. Noren, A.J., Bierman, P.R., Steig, E.J., Lini, A., Southon, J.A., 2002. Millennial-scale storminess variability in the northeastern United States during the Holocene. Nature 419, 821–824.
24
G.I. Zaitseva, V.A. Dergachev / Quaternary International 203 (2009) 19–24
O’Brien, S.R., Mayewski, P.A., Meeker, L.D., Meese, D.A., Twickler, M.S., Whitlow, S.I., 1995. Complexity of Holocene climate as reconstructed from a Greenland ice core. Science 270, 1962–1964. Oshibkina, S.V. (Ed.), 1996. The Neolithic of the Northern Eurasia. Nauka, Moscow, pp. 231–248 (in Russian). Rind, D., Lean, J., Healy, R., 1999. Simulated time-dependent climate response to solar radiative forcing since 1600. Journal of Geophysical Research 104, 1973–1990. Stuiver, M., Reimer, P.J., Bard, E., Beck, J.W., Burr, G.S., Hughen, K.A., Kromer, B., McCormac, G., van der Plicht, J., Spurk, M., 1998. Intcal98 radiocarbon age calibration 24,000–0 cal BP. Radiocarbon 40 (3), 1041–1083. Timofeev, V.I., Zaitseva, G.I., Dolukhanov, P.M., Shukurov, A.M., 2004. Radiocarbon Chronology of the Neolithic of the Northern Eurasia. Thesa, St. Petersburg,157 p. (in Russian). Timofeev, V.I., Zaitseva, G.I., 1997. Some aspects on radiocarbon chronology of the Neolithic cultures in the Forest zone of the European part of Russia. In: Proceedings of the VII Nordic Conference on the Application of Scientific Methods in Archaeology. ISKOS, 11, pp. 15–23. Vasiliev, S.S., Dergachev, V.A., 2002. The w2400-year cycle in atmospheric radiocarbon concentration: bispectrum of 14C data over the last 8000 years. Annales Geophysicae 20, 115–120.
Weber, S.L., Crowley, J., van der Schrier, G., 2004. Solar irradiance forcing of centennial climate variability during the Holocene. Climate Dynamics 22, 539–553. Zaitseva, G.I., Timofeev, V.I., Dergachev, V.A., Sementsov, A.A., 1997a. Some aspects on the distribution on radiocarbon dates form the Mesolithic and Neolithic of European Russia. In: Proceedings of the VII Nordic Conference on the Application of Scientific Methods in Archaeology. ISKOS, 11, pp. 33–39. Zaitseva, G.I., Dergachev, V.A., Timofeev, V.I., Sementsov, A.A., 1997b. Radiocarbon chronology of the archaeological sites for European Russia and natural changes: the database investigation. Radiocarbon and Archaeology 2, 4–12. St. Petersburg (in Russian). Zaitseva, G.I., Dergachev, V.A., Timofeev, V.I., Sementsov, A.A., 1998. 14C chronology of archaeological sites in European Russia and changes in environmental processes: a database investigation. Radiocarbon 40 (2), 759–767. Zaitseva, G.I., van Geel, B., 2004. The occupation history of the southern Eurasian steppe during the Holocene: chronology, the calibration curve and methodological problems of the Scythian chronology. In: Impact of Environment on Human Migration. NATO Series, vol. 42. Kluwer Academic Publishers, pp. 63–83.