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RADIOCARBON, Vol 55, Nr 1, 2013, p 179–184

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VALIDATION OF RADIOCARBON DATES OF WOOLLY MAMMOTH REMAINS FROM NORTHWESTERN CHUKOTKA, RUSSIA Sergey L Vartanyan North-East Interdisciplinary Scientific Research Institute n.a. N.A. Shilo, Far East Branch, Russian Academy of Sciences (NEISRI FEB RAS), 16 Portovaya St., Magadan 685000, Russia. Email: [email protected]. ABSTRACT. This paper presents the results of cross-dating of mammoth remains from northwestern Chukotka, northeastern Siberia. Our results suggest that several dates obtained by the radiocarbon laboratory at the Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (laboratory code SOAN) appear to be too recent. Cross-dating in different laboratories revealed significant differences in the ages obtained compared to SOAN. This highlights the need to critically assess 14C dates, and where necessary, confirm results in independent laboratories.

INTRODUCTION

The region of as northwestern Chukotka includes the Rauchua-Chaun and Valkarkay lowlands, as well as the Wrangel and Ayon islands (Figure 1). The Late Pleistocene history of this area is critically important for the biogeography and paleogeography of the entire Beringian Arctic, because this is the only easily accessible area within the Beringian northern plain. This area also provided refugia for Pleistocene flora and fauna. Recognizing the importance of the region, I have been collecting woolly mammoth (Mammuthus primigenius) remains in northwestern Chukotka for the last 20 yr, and numerous radiocarbon dates were obtained on these specimens.

Figure 1 Map of northwestern Chukotka

Considering the importance of this work in reconstructing mammoth extinction, we paid particular attention to the quality of 14C dating to prevent erroneous dates from appearing in the scientific literature. However, due to an unfortunate misunderstanding, some preliminary and, as it later turned out, incorrect dates were cited in a recent study (Kuzmin 2010).

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Two of the dates on woolly mammoth from northwestern Chukotka were published by Kuzmin (2010: Table 1) as “8700±?, lab. no is not available” and “9000±?, lab. no is not available.” The citation for these 2 dates comes from a published abstract of an oral presentation at the 2nd International Congress “The World of Elephants” (Vartanyan et al. 2005:195–6): “Two radiocarbon dates of mammoth bones from Kyttyk Peninsula of the Holocene age, 8,700–9,000 years ago, completely correlate with the time of appearance on Wrangel Island after approximately 3,000 years of their absence on the island.” These dates had been received in 2003 as part of a series of 14C dates from mammoth remains collected on Chukotka. This series was dated at the Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (laboratory code SOAN). Two results from the series had early Holocene ages and they were discussed in my presentation at the congress. These dates were formally released by the laboratory as 8735 ± 85 BP (SOAN-5545) and 8985 ± 70 BP (SOAN-5546). It is unfortunate that these preliminary findings were included in Kuzmin (2010) since the dates later turned out to be too young. To clear up this misunderstanding and to prevent the propagation of these erroneous ages, the corrected 14C dates from these 2 samples are presented herein, as well as those of other mammoth remains from northwestern Chukotka. At the time these ages were first presented, they had not been tested by additional dating. Understanding the considerable importance of early Holocene mammoth dates from mainland Siberia, we decided to commission redating of the samples before publication of the results. In 2005 and 2006, the Tandem Laboratory at Uppsala University (laboratory code Ua) and the Laboratory of the Geographical Institute of St. Petersburg State University (laboratory code LU) redated these “early Holocene” samples. Both laboratories provided 14C ages that were Late Pleistocene, which strongly suggests that the Holocene dates produced at the SOAN Laboratory were erroneous. RESULTS AND DISCUSSION Comparison of Dates from Wrangel Island, NE Siberia, Russia

The first verifiable Holocene dates on woolly mammoth were obtained in 1990 from Wrangel Island. We published this discovery in 1993 when we had 29 dates of Holocene age (Vartanyan et al. 1993). This is an example of successful cross-dating, since all dates were processed in 2 different 14C laboratories: the Geographical Institute of St. Petersburg State University (laboratory code LU) and the Geological Institute of the Russian Academy of Sciences, Moscow (GIN). In subsequent years, we involved several other laboratories: the Tandem Laboratory at Uppsala University (Ua); the Institute for the History of Material Culture of the Russian Academy of Sciences, St. Petersburg (LE); and the NSF Arizona AMS Facility at University of Arizona (AA). The ages of these samples were thus confirmed by cross-dating in several laboratories, and we were therefore confident in the quality of the published results. Several examples of cross-dating of mammoth and woolly rhinoceros bones from Wrangel Island are given in Tables 1–4. Table 1 Results of 14C cross-dating of 1 tusk and 2 bones from an individual woolly mammoth from Wrangel Island, NE Siberia (Vartanyan et al. 2008). Sample code and material

Lab nr

14C

69A, mandible 69V, humerus 20-M, tusk 20-M, tusk

LU-3515 GIN-8654 GIN-6990 LU-2736

6830 ± 40 6720 ± 50 6750 ± 30 6760 ± 50

date (yr BP)

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Table 2 Results of 14C cross-dating of mammoth teeth from Wrangel Island, NE Siberia (Long et al. 1994). 14C

Sample code and material GUS-9, mammoth tooth PIK-1, mammoth tooth

date (yr BP) and lab nr

6260 ± 50 (LU-2799) 7250 ± 60 (LU-2809)

6360 ± 60 (AA-11529) 7295 ± 95 (AA-11530)

Table 3 Results (in 14C yr BP) of 14C cross-dating of mammoth tusks from Wrangel Island, NE Siberia. Samples 25-M and 26-M were likely 2 tusks of 1 individual (Arslanov et al. 1998). Sample code Lab name and methoda

24-M

Radiologiskdatering, Trondheim, AMS Geological Survey of Finland, GPC SURRC, East Kilbride, LSC IHMC RAS, St. Petersburg, LSC NERC, East Kilbride, LSC NERC, East Kilbride, AMS St. Petersburg State University, LSC Number of dates per sample

6225 ± 80 6155 ± 40 6110 ± 90 6110 ± 40

a AMS

25-M

6720 ± 110 6660 ± 30 6640 ± 70 6360 ± 40 6625 ± 40 6250 ± 60 6660 ± 55 6100 ± 70 6640 ± 70 6 7

26-M

27-M

28-M

6545 ± 30 6620 ± 50 6650 ± 50 6355 ± 45 6725 ± 55 6430 ± 70 6

4570 ± 55 7580 ± 60 7450 ± 30 4340 ± 50 4530 ± 70 7460 ± 70 4445 ± 45 7380 ± 45 4445 ± 50 7450 ± 65 4570 ± 80 7340 ± 120 6 6

= accelerator mass spectrometry; GPC = gas proportional counting; LSC = liquid scintillation counting.

Table 4 Results of cross-dating of woolly rhinoceros bones from Wrangel Island, NE Siberia. Woolly rhinoceros remains (Coelodonta antiquitatis) from a single animal Woolly rhinoceros femur Lab nr 14C date (yr BP)

Horn

Radius

OxA-19493 36,040 ± 240

LE-5275 36,600 ± 1600

(Coelodonta antiquitatis) OxA-19364 37,780 ± 310

LE-5276 35,200 ± 1200

The various methods of 14C dating of bone remains, and the reliability of such dates, have been discussed frequently (e.g. Arslanov and Svezhentsev 1993; Vartanyan et al. 1995). It is known that 14C dates from the organic fraction of bones (i.e. collagen) of good preservation in permafrost are of high reliability. Nonetheless, cross-dating in different laboratories often shows differences in age. The variation in the results is larger than might be predicted given the use of single samples but may reflect differences in standards, any natural variation in the material, and pretreatment effects, especially the removal of contaminants from bone collagen (Scott et al. 1990; Arslanov et al. 1998). Comparison of Dates from Continental Chukotka and Ayon Island, NE Siberia, Russia 14C

dating of mammoth remains from western Chukotka (Rauchua-Chaun Lowland, Ayon Island, and Valkarkay Lowland) has mainly been performed in 3 laboratories: the Geographical Institute of St. Petersburg State University (LU); the Oxford Radiocarbon Accelerator Unit (OxA); and the Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (SOAN). In addition, several dates were obtained from the Lawrence Livermore National Laboratory (CAMS) and the Tandem Laboratory at Uppsala University (Ua). Collection of further mammoth remains in the area is currently underway, and we continue to practice cross-dating of samples (Tables 5–7).

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S L Vartanyan Table 5 Results of cross-dating of mammoth tusk from western Chukotka (6949.2N, 17340.5E) at the CAMS and LU laboratories. 14C

Sample code and material CHM-10, mammoth tusk

date (yr BP) and lab nr

15,235 ± 50 (CAMS-110323)

15,440 ± 190 (LU-4460)

Twenty-two mammoth samples were dated in the Novosibirsk (SOAN) laboratory, a laboratory we had not previously used. The series of 14C dates received from the SOAN laboratory had some unusual features that differed from series previously received from other laboratories. In particular, 2 dates were of Early Holocene age (see above) and “infinite” dates were absent. Since such results were unusual, we redated some of the samples in other laboratories, with the hope that the early Holocene age would be confirmed. However, cross-dating of the same samples processed in the SOAN laboratory gave very different results (Tables 6 and 7), and in particular we were unable to reproduce the Holocene dates, which proved to be much too young (Table 6). Table 6 Results of cross-dating of mammoth bones from Kyttyk Peninsula in 3 laboratories. 14C

Sample description Mammoth femur, W Chukotka, Kyttyk Peninsula, Teyukulkay River (6911.84N, 16758.21E) Mammoth humerus, W Chukotka, Kyttyk Peninsula, section CHG-7 (6933.8N, 16812.3E)

date (yr BP) and lab nr

8735 ± 85 28,800 ± 350 (SOAN-5545) (LU-5174) 8985 ± 70 — (SOAN-5546)

26,740 ± 490 (Ua-32374) 16,765 ± 150 (Ua-32373)

These results suggest that dates from the given series of SOAN laboratory show a systematic error, so we decided not to use SOAN dates for further work and publication. The unexplained younger results occurred even for samples that did not contain any 14C according to analyses in the Oxford laboratory (Table 7). Table 7 Results of cross-dating of mammoth bone samples from western Chukotka and Ayon Island at the SOAN and OxA laboratories. Sample description RS-16, mammoth tusk, W Chukotka, Ngagleyngyveem River (6900.0N, 16819.81E) RS-17, mammoth femur, W Chukotka, Ngagleyngyveem River (6859.61N, 16824.361E) A08-12, mammoth scapula, W Chukotka, Kyttyk Peninsula, Emukkuvnyan River (6911.94N, 16741.75E) A08-13, mammoth tusk, W Chukotka, Kyttyk Peninsula, Emukkuvnyan River (6911.94N, 16741.75E) A08-14, mammoth pelvis, Ayon Island (6935.19N, 16914.48E) A08-15, mammoth tibia, W Chukotka, Nagleynenvaam River (6900.34N, 16814.56E) A08-16, mammoth tusk, W Chukotka, Nagleynenvaam River (6900.26N, 16812.53E) A08-18, mammoth tibia, Ayon Island (6934.69N, 16843.86E) a Dated

14C

date (yr BP) and lab nr

28,330 ± 490 (SOAN-5542) 16,350 ± 255 (SOAN-5537) 39,870 ± 415 (SOAN-5687) 23,960 ± 220 (SOAN-5688) 18,320 ± 230 (SOAN-5539) 16,330 ± 170 (SOAN-5540) 20,980 ± 200 (SOAN-5541) 24,310 ± 250 (SOAN-5544)

31,470 ± 180 (OxA-18497) 49,600 ± 1000 (OxA-18498) 50,300 ± 1000 (OxA-20033) 47,450 ± 700 (OxA-20034) >62,600 (OxA-20029) 23,610 ± 90 23,740 ± 90 (OxA-20043)a 50,700 ± 1000 (OxA-20045) 25,610 ± 110 (OxA-20030)

twice.

The reason for the younger results from the SOAN laboratory is unknown, but may have been due to errors during preliminary sample processing (i.e. collagen extraction) or to an unexplained contamination. It should be mentioned that several times previously parallel samples were run at

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Novosibirsk and other labs, including the University of Arizona (AA), Oxford University (OxA), and Groningen University (GrA) (Kuzmin et al. 2001; Derevianko et al. 2003:124; Orlova et al. 2004), and the results were quite satisfactory. CONCLUSION

The accumulation of a large and representative collection of 14C dates from animal remains across large geographical areas can be extremely informative. However, accomplishing this requires significant costs, as well as considerable effort in field and analytic work. Since the early 1980s, when the first large series of 14C dates began to be generated, the principles and procedures for how these data should be obtained have progressively become more refined. Some of these important principles were suggested recently (Nikolskiy et al. 2011; Lister and Stuart 2013) and highlight the importance of auditing 14C date series by careful and objective elimination of unreliable results. The revised dates for the mammoth samples from northwestern Chukotka are an example of this phenonemon and should serve to correct the record of the previously reported erroneous ages. The results of 14C dating require, in many cases, cross-checking before conclusions are drawn. The following points must be stressed when the reliability of 14C dates is assessed: • Single dates, even from a reliable laboratory, could be mistaken; • The frequency distribution of dates should be generally similar to other date series from the region; any anomalies in the distribution should indicate a need for cross-checking; • Cross-dating shows that there is a difference in 14C dating even of well-preserved permafrost samples (Tables 2, 3, 6). The difference can be several hundred years even for Holocene dates, and it appears to increase with sample age, reaching a few thousand years in samples more than 30 kyr old. ACKNOWLEDGMENTS 14C dating was funded through grant NF/2008/1/17 from the Natural Environment Research Council

(UK). I am also thankful to Prof Daniel Fisher from the Museum of Paleontology, University of Michigan, USA, for his help in 14C dating and organizing of fieldworks. I appreciate the help of Dr Diana Solovyeva from the Institute of Biological Problems of the North, Far Eastern Branch of the Russian Academy of Sciences, Russia, during fieldwork and for language editing. Thanks also go to Dr Love Dalen (Swedish Museum of Natural History) and Prof Adrian Lister (The Natural History Museum, London) for helpful comments on the manuscript. REFERENCES Arslanov KhA, Svezhentsev YuS. 1993. An improved method for radiocarbon dating fossil bones. Radiocarbon 35(3):387–91. Arslanov KhA, Cook GT, Gulliksen S, Harkness DD, Kankainen T, Scott EM, Vartanyan S, Zaitseva GI. 1998. Consensus dating of mammoth remains from Wrangel Island. Radiocarbon 40(1):289–94. Derevianko AP, Molodin VI, Zenin VN, Leshchinsky SV, Mashchenko EN. 2003. Pozdnepaleoliticheskoe Mestonakhozhdenie Shestakovo [The Late Paleolithic Locality of Shestakovo]. Novosibirsk: Institute of Ar-

chaeology and Ethnography Press. 168 p. In Russian. Kuzmin YV. 2010. Extinction of the woolly mammoth (Mammuthus primigenius) and woolly rhinoceros (Coelodonta antiquitatis) in Eurasia: review of chronological and environmental issues. Boreas 39(2): 247–61. Kuzmin YV, Baryshnikov GF, Jull AJT, Orlova LA, van der Plicht J. 2001. Radiocarbon chronology of the Pleistocene fauna from Geographic Society Cave, Primorye (Russian Far East). Current Research in the Pleistocene 18:106–8.

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Lister AM, Stuart AJ. 2013. Extinction chronology of the woolly rhinoceros Coelodonta antiquitatis: reply to Kuzmin. Quaternary Science Reviews 62:144–6. Long A, Sher A, Vartanyan S. 1994. Holocene mammoth dates. Nature 369(6479):364. Nikolskiy PA, Sulerzhitsky LD, Pitulko VV. 2011. Last straw versus Blitzkrieg overkill: climate-driven changes in the Arctic Siberian mammoth population and the Late Pleistocene extinction problem. Quaternary Science Reviews 30(17–18):2309–28. Orlova LA, Zenin VN, Stuart AJ, Higham TFG, Grootes PM, Leshchinsky SV, Kuzmin YV, Pavlov AF, Maschenko EN. 2004. Lugovskoe, western Siberia: a possible extra-Arctic mammoth refugium at the end of the Late Glacial. Radiocarbon 46(1):363–8. Scott EM, Long A, Kra RS, editors. 1990. Proceedings of the International Workshop on Intercomparison of 14C Laboratories. Radiocarbon 32(3):259–397.

Vartanyan SL, Garutt VE, Sher AV. 1993. Holocene dwarf mammoths from Wrangel Island in the Siberian Arctic. Nature 362(6418):337–40. Vartanyan SL, Arslanov KhA, Tertychnaya TV, Chernov SB. 1995. Radiocarbon evidence for mammoths on Wrangel Island, Arctic Ocean, until 2000 BC. Radiocarbon 37(1):1–6. Vartanyan SL, Tikhonov AN, Orlova LA. 2005. The dynamics of mammoth distribution in the last refugia in Beringia. In: Agenbroad LD, Symington RL, editors. The World of Elephants. Short Papers and Abstracts of the 2nd International Congress. Hot Springs: Mammoth Site of Hot Springs Publishers. p 195–6. Vartanyan SL, Arslanov KhA, Karhu JA, Possnert G, Sulerzhitsky LD. 2008. Collection of radiocarbon dates on the mammoths (Mammuthus primigenius) and other genera of Wrangel Island, northeast Siberia, Russia. Quaternary Research 70(1):51–9.