Kurbanov, R. | bioRxiv Science

bioRxiv2025

Stable isotopes of soil provide insights into hominin paleoenvironments in the Khovaling Loess Plateau of Southern Tajikistan, Central Asia

This study presents a multi-proxy investigation of loess-paleosol sequences from the Khovaling Loess Plateau (KLP) in southern Tajikistan to explore long-term human-environment interactions during the Early Paleolithic. This region has been the focus of numerous archaeological projects since Soviet times, as it contains evidence of some of the oldest ([~]0.9 Ma) hominin occupations in Central Asia and is one of the key regions connecting eastern Asia to centers of hominin evolution that lie to the west. Previous archaeological expeditions have discovered rich collections of stone tools from alternating non-pedogenically modified loess and paleosol sequences at the archaeological sites of Karatau, Lakhuti, Obi-Mazar, and Kuldura. We analyzed lipid biomarkers such as n-alkanes, polycyclic aromatic hydrocarbons (PAHs), together with newly generated stable isotopes ({delta}{superscript 1}3C, {delta}{superscript 1}N), magnetic susceptibility, and archaeological assemblages from three sites: Obi-Mazar/Lakhuti (on-site), and non-artifact-bearing strata from Kuldara (near-site) and Khonako-II (off-site), focusing on pedocomplexes (PCs) 4, 5, and 6 and their intercalated loess layers. High odd-over-even predominance (OEP) and average chain lengths (ACL) suggest that soil organic matter is predominantly derived from higher-order terrestrial plants, with better preservation in paleosols compared to loess layers. The inverse correlations of {delta}{superscript 1}3C with TOC and C/N reflect organic matter degradation, while elevated {delta}{superscript 1}N in paleosols suggests enhanced nitrogen cycling under warmer and drier conditions. Magnetic susceptibility and {delta}{superscript 1}3C trends reveal a progressive shift toward open grassland ecosystems since [~]0.8 Ma, with intensified pedogenesis during interglacial stages MIS 11, 13, and 15. The spatial distribution of PAH concentrations and lithic artifact densities further highlights human-environment interactions in the KLP locality. Obi-Mazar exhibits abundant lithic materials and high PAH levels, indicating repeated occupation and frequent burning in a resource-rich riverine setting. Kuldara exhibits moderate PAHs but minimal artifacts, whereas Khonako-II records only a minimal level of signals, reflecting a decrease in human impact with distance from the water source. Together, these findings demonstrate that Early Paleolithic hominins preferentially occupied ecologically stable, pedogenically developed zones during interglacial phases, contributing to localized fire regimes and shaping their landscapes. This study provides a refined paleoenvironmental framework for understanding hominin adaptations in Central Asia during the Pleistocene.

ecology↗

bioRxiv2024

Cleaning the Dead: Optimized decontamination enhances palaeoproteomic analyses of a Pleistocene hominin tooth from Khudji, Tajikistan

The study of ancient proteins preserved in a range of archaeological, cultural heritage, and palaeontological materials is increasingly contributing to our understanding of human evolution and archaeological research questions. Many of the specimens studied have been excavated and stored for a significant duration prior to their proteomic analysis. Human handling and storage environments therefore provide ample opportunities for protein contamination onto and into specimens of interest to palaeoproteomic studies. As such, modern protein contamination limits access to endogenous proteomes. Here, we compare five approaches of bone protein decontamination applied to a Pleistocene Equus sp. bone fragment contaminated with a modern dog salivary proteome. We find that all tested methods reduce the protein contamination, but with different efficiencies. We find that a brief bleach wash is the most effective approach in removing modern protein contamination, and that no additional damage is caused to the endogenous proteome by this treatment. Next, we apply this approach to a hominin tooth found at Khudji, a Late Pleistocene archaeological site in Tajikistan. We demonstrate that a brief bleach wash removes almost all human skin protein contamination while retaining the endogenous hominin dentine proteome. Subsequent phylogenetic analysis of the Khudji dentine proteome allowed determination that the specimen is likely not a Denisovan, but still leaves ambiguity between an assignment to either modern humans or Neanderthals.

evolutionary biology↗