Researchers have identified the earliest known lethal plague outbreaks among hunter-gatherer communities near Lake Baikal, dating to approximately 5,500 years ago.

研究人員在貝加爾湖附近的採集狩獵社區中，發現了已知最早的致命鼠疫爆發，時間約在 5,500 年前。

The investigation centered on four cemetery sites along the Angara River, where palaeogenomic analysis of dental cementum revealed Yersinia pestis DNA in 39% of the sampled individuals. This detection rate, when contrasted with known medieval plague pits, suggests a high incidence of infection within these populations. The data indicate two distinct epidemiological phases, separated by several centuries, characterized by acute mortality events. Kinship reconstruction via identity-by-descent (IBD) segments confirms that the disease affected small familial groups, supporting the hypothesis of human-to-human transmission.

此項調查集中在安加拉河沿岸的四個墓地，透過對牙骨質的古基因組分析，發現 39% 的樣本中含有鼠疫桿菌 (Yersinia pestis) DNA。與已知的中世紀鼠疫坑相比，此檢測率顯示出這些人群中的感染率極高。數據顯示有兩個截然不同的流行病階段，中間相隔數個世紀，特徵為急性死亡事件。透過同源等位基因 (IBD) 片段的親屬重建，證實該疾病影響了小型家庭群組，支持了人傳人的假設。

From a phylogenetic perspective, these strains diverge ancestrally to all known ancient and modern plague clades, constraining the emergence of Y. pestis to before approximately 5,700 years ago. A critical genomic finding is the absence of the ymt gene and YpfΦ prophage, which are essential for flea-mediated transmission and the manifestation of bubonic plague. Conversely, the presence of the ypm superantigen locus—similar to that found in Y. pseudotuberculosis—is hypothesized to have induced severe inflammatory responses. This genetic profile, combined with osteological data, reveals a mortality distribution heavily skewed toward prepubescent children (aged 8 to 11 years), suggesting a heightened vulnerability in this demographic.

從系統發生學的角度來看，這些菌株在演化上早於所有已知的古代與現代鼠疫分支，將鼠疫桿菌的出現時間限制在約 5,700 年前。一個關鍵的基因組發現是缺乏 ymt 基因與 YpfΦ 原噬菌體，而這些對於跳蚤媒介傳播以及腺鼠疫的表現至關重要。相反，存在 ypm 超抗原位點（類似於在假鼠疫桿菌中發現的），據推測會誘發嚴重的炎症反應。此基因圖譜結合骨骼數據顯示，死亡分佈嚴重偏向青春期前的兒童（8 至 11 歲），顯示該人口群體具有更高的脆弱性。

Regarding the zoonotic origin, the researchers posit that the outbreaks resulted from spillover events from wild marmot reservoirs, likely through the consumption of raw organs or contact during butchery. Once introduced to the human population, the absence of bubonic virulence factors suggests the disease manifested as pneumonic plague, spreading via respiratory aerosols. This evidence challenges the prevailing academic consensus that high population densities and the transition to agricultural lifestyles were prerequisite conditions for lethal plague epidemics.

關於人畜共患起源，研究人員認為爆發源於野生土撥鼠儲層的溢出事件，可能是透過食用生內臟或在屠宰過程中接觸而引起。一旦引入人類群體，由於缺乏腺鼠疫致病因子，顯示該疾病表現為肺鼠疫，經由呼吸道氣溶膠傳播。此證據挑戰了目前主流的學術共識，即高人口密度與轉向農業生活方式是致命鼠疫大流行的前提條件。

The study confirms that lethal plague outbreaks occurred in small, mobile hunter-gatherer groups long before the Neolithic agricultural transition.

研究證實，早在新石器時代農業轉型之前，小型移動的採集狩獵群組就已發生過致命的鼠疫爆發。