Obi-Rakhmat Grotto

Obi-Rakhmat Grotto

Shown within Uzbekistan
Location	Uzbekistan
Region	Tien Shan Mountains
Altitude	1,250 m (4,101 ft)
Length	20 metres (66 ft)
Width	9 metres (30 ft)
Height	11.8 metres (39 ft)
History
Periods	Middle Paleolithic
Associated with	Neanderthals

Obi-Rakhmat Grotto is a Middle Paleolithic paleoanthropological site in Uzbekistan that yielded Neanderthal fossil remains.

Obi-Rakhmat Grotto is a shallow karstic cavity in the east of Uzbekistan, at the southwestern end of the Talassky Alatau Range of the western Tien Shan Mountains. The site is situated near the junction of the Chatkal and Pskem Rivers, at an elevation of 1,250 m asl (above sea level), 100 km northeast of Tashkent, Uzbekistan. The cavity is 20 m wide at the entrance, 9 m long and 11.8 m high.

Excavations

Obi-Rakhmat Grotto was discovered in 1962 by a research team from the Institute of History and Archaeology, Academy of Sciences of Uzbekistan, headed by A. R. Mukhamedzhanov. Initial excavations were carried out under the supervision of M. M. Gerasimov and H. K. Nasretdinov. Afterwards, research was directed by R. H. Suleimanov in 1964–1965. Excavations were later renewed in 1998 by an international multidisciplinary team under the general direction of academician Anatoly Derevyanko and principal investigators Andrei Krivoshapkin and Patrick Wrinn.

Stratigraphy

The depositional sequence in the grotto includes 22 lithological strata and reaches a depth of about 10 m, divided into 22 stratigraphic units, based on texture and archaeological content. The rich assemblages of lithic artefacts include core-burins on large flakes, unidirectional blade and flake cores, (mostly retouched blades and retouched pointed blades, while other common types include burins, atypical end scrapers, sidescrapers (grattoir de côté) and Mousterian points) and Levallois forms. The Levallois forms are concentrated in the basal layers, especially stratum 19. The principal raw material is local silicified limestone.

Obi-Rakhmat blank industry differ in only minor ways from the classic and elongate Levallois points from Kara-Bom. Obi-Rakhmat displays many similar features with both late Middle Paleolithic and early Upper Paleolithic complexes in Southwest Asia and the Siberian Altai. It appears that the Upper Paleolithic in Siberian Altai emerged from a local Middle Paleolithic established in the area perhaps 100–50 thousand years ago.

Stratum 19 seems to represent a series of exceptionally intensive occupational episodes because of the high density of finds and the presence of charcoal, burnt bones, and artefacts representing combustion activity.

Based on material from the most recent excavations (2007–2009), it appears reasonable to assume that the Obi-Rakhmat lithic artefacts represent a transitional Middle-to-Upper Paleolithic industry.

Chronology

The uranium-series (uranium-thorium dating, ²³⁴U–²³⁰Th) determinations on travertines range between 70,000–100,000 years BP. These results are less secure due to the high uranium content and the presence of detritus, which contaminates dated sediments (travertine). ESR (electron paramagnetic resonance) analysis (linear uptake model) on eight bovid tooth enamel give an age estimation of ca. 57–73 ka BP (strata 12–14) and ca. 87 ka BP (basal stratum 21.1). The preliminary results of OSL (optically stimulated luminescence) dating on sediment from several profile locations gave uniform ages for all cultural succession: stratum 5.1 (56,000 ± 3200 yr), stratum 8.1 (60,100 ± 3000 yr), and stratum 21.2 (61,400 ± 3600 yr):

“As for issue of the age of Obi-Rakhmat sequence being possibly beyond the limit of sensitivity of ¹⁴C dating method (see Derevianko et al. 2004:202), we can say now that at least layer 9, dated to ~42,100 BP, is well within the limit of ¹⁴C (radiocarbon) age detection. Possibly, the age of layer 14.1 (~48,800 BP) may be a minimal estimate, but more study is necessary to precisely determine the age. Thus, the question about the true age of layer 14 at Obi-Rakhmat site is still open to discussion, but there is no 'discrepancy' between the ¹⁴C and U-series dates (see Skinner et al. 2007:1237).”

Fauna

The faunal assemblage is dominated by Siberian mountain goat (Capra sibirica) and red deer (Cervus elaphus), which constitute 90% of the identified specimens. Other faunal remains include sheep (Ovis sp.), wild boar (Sus scrofa), fox (Vulpes vulpes) and marmot (Marmota sp.). Carnivore remains are rare.

Evidence of human modification of the bones, including cut marks, conchoidal impact scars, and burning, is consistently present. The lithic artefacts and faunal remains recovered at Obi-Rakhmat suggest that the site was repeatedly used by hominins as a short-term hunting and butchery station.

Hominin remains

In 2003, hominin remains were recovered from stratum 16. They consist of 6 isolated permanent maxillary teeth and 121 cranial fragments from a single subadult (juvenile).

The Obi-Rakhmat fossil expresses a relatively Neandertal-like dentition coupled with more ambiguous cranial anatomy (e.g., its parietal size and aspects of the external surface of its temporal) that does not conform to existing descriptions of subadult Neandertals. It represents an individual of roughly 9–12 years of age at death, estimated from the examination of relative root development and degree of dental wear.

The subadult bone yielded uncalibrated dates ranging from 29,990 ± 500 years BP to 37,800 ± 450 years BP. To date, the best chronological estimate for the hominid remains from Obi-Rakhmat is ca. 60–90 ka BP or ~70 ka.

DNA analysis

The mitochondrial DNA (mtDNA) sequences from the Obi-Rakhmat subadult (OR–1) and Teshik Tash child fall within the European Neanderthal mtDNA variation, showing that both individuals belonged to a population related to European and western Asian Neanderthals. However, the Teshik Tash mtDNA sequence seems to be more closely related to the mtDNA sequence from Scladina in western Europe than to the sequence from Okladnikov Cave. The absence of deep mtDNA divergence shows that Central Asian, Caucasian and European Neanderthals were not separated for a long time, supporting the view that Central Asia (most of the Russian plains) was relatively recently colonized by Neanderthals, maybe not before an exceptionally warm episode 125,000 years ago (MIS 5e).

See also

• OR-1
• Denisova Cave