Environmental and cultural transformations in the Lake Baikal Region reflect hemispheric-scale changes in temperature and atmospheric circulation over the past 8800 years
Bibliographic record
Abstract
Characterised by heterogeneous microclimatic conditions, a sharp vegetation gradient and a rich archaeological record, Olkhon Island offers a unique setting to investigate past climate change and its potential influence on cultural trajectories in the Lake Baikal Region (LBR). Palynological and geochemical analyses of the uppermost 556 cm section of the 750 cm long, radiocarbon-dated sediment core (Nur-II) from Lake Nurskoye (53°3'N, 106°58'E; 456 m a.s.l.) at the western end of Olkhon Island reveal several long- and short-term climate shifts over the last 8800 years. Forest expansion beginning in the Early Holocene peaked during the second half of the 7th millennium cal BP, followed by a continuous decline culminating around 1500 cal yr BP, when open steppe vegetation reached its maximum extent. This pattern supports the long-debated hypothesis that landscape openness and the associated availability of herbivorous game were key drivers of population size, social practices and subsistence strategies among Mesolithic, Neolithic and Bronze Age hunter-gatherer communities in the region. The maximum expansion of steppe vegetation (ca. 3400–800 cal yr BP) likely attracted Bronze Age pastoral groups who migrated into the area around 3300 cal yr BP, as corroborated by the Nur-II palynological record and archaeozoological data from the LBR. However, the pollen data show no evidence that the mixed foraging-pastoral subsistence was supplemented by crop cultivation prior to the Middle Ages (i.e. 1360 cal yr BP). The pollen-inferred moisture trends on millennial to centennial scales, including the 8.2 and 4.2 ka BP cooling events, show a positive correlation with the intensity of the Asian summer monsoon circulation throughout the study period. This suggests that the region’s hydrology was primarily controlled by a south-easterly circulation regime during the Early–Middle Holocene, while westerly-derived moisture became increasingly important after ca. 7000 cal yr BP. • Detailed palynological and geochemical records from Lake Nurskoye (Olkhon Island). • Major changes in vegetation and lake sediment geochemistry occurred synchronously. • The collapse of the Kitoi culture 6660 cal yr BP followed the maximum expansion of the forests. • The expansion of steppe 3400–800 cal yr BP attracted Bronze and Iron Age pastoralists. • Moisture trends show a positive correlation with easterly and westerly circulation patterns.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".