Scientists found a very old and deadly sickness in Siberia. It happened 5,500 years ago.

科學家在西伯利亞發現了一種非常古老且致命的疾病，發生於 5,500 年前。

Scientists looked at old teeth from four cemeteries. They found the plague germ in many people. This sickness killed many people in small families.

科學家研究了四個墳場的古齒，發現許多人都染有鼠疫菌。這種疾病殺死了許多小家庭中的成員。

The sickness was different from the plague today. It did not come from fleas. Instead, it moved from person to person through the air. Many children between 8 and 11 years old died.

這種疾病與今日的鼠疫不同，並非由跳蚤傳播，而是透過空氣在人與人之間傳染。許多 8 到 11 歲的兒童因此死亡。

The people got the sickness from wild animals called marmots. They probably touched the animals or ate them. These people did not farm. They moved and hunted for food.

人們是從一種稱為旱地鼠的野生動物身上染病的，可能是因為接觸或食用了這些動物。這些人並不從事農耕，而是遷徙並狩獵食物。

This study shows that the plague killed small groups of hunters a long time ago.

這項研究顯示，鼠疫在很久以前殺死了小型狩獵族群。

Researchers have discovered the earliest known deadly plague outbreaks among hunter-gatherer communities near Lake Baikal, dating back approximately 5,500 years.

研究人員在貝加爾湖附近的狩獵採集者社群中，發現了已知最早的致命鼠疫爆發，可追溯至約 5,500 年前。

The study focused on four cemetery sites along the Angara River. By analyzing DNA from teeth, scientists found Yersinia pestis (the plague bacteria) in 39% of the individuals. This high rate suggests that the disease was very common in these groups. The data show two separate periods of high mortality, separated by several centuries. Furthermore, genetic evidence confirms that the disease affected small family groups, which indicates that the plague spread from person to person.

這項研究集中在安加拉河沿岸的四個墓地。透過分析牙齒的 DNA，科學家在 39% 的個體中發現了鼠疫桿菌（Yersinia pestis）。如此高的比率顯示該疾病在這些群體中非常普遍。數據顯示有兩個分開的高死亡率時期，中間相隔數個世紀。此外，基因證據證實該疾病影響了小型家庭群組，顯示鼠疫是透過人與人傳播的。

From a genetic perspective, these strains are older than all other known plague types, meaning the bacteria emerged at least 5,700 years ago. Interestingly, these ancient strains lacked the specific genes needed for fleas to spread the disease, meaning it was not the 'bubonic' plague. Instead, researchers believe it was a pneumonic plague that spread through the air. This version of the disease was particularly deadly for children aged 8 to 11, who showed the highest rates of death.

從基因角度來看，這些菌株比所有其他已知的鼠疫類型都要古老，意味著細菌至少在 5,700 年前就已出現。有趣的是，這些古老菌株缺乏跳蚤傳播疾病所需的特定基因，因此並非「腺鼠疫」。相反，研究人員認為這是透過空氣傳播的「肺鼠疫」。此版本的疾病對 8 到 11 歲的兒童特別致命，其死亡率最高。

Regarding the origin of the disease, the researchers emphasized that the outbreaks likely started when humans came into contact with wild marmots, possibly by eating raw organs. This discovery is significant because it challenges the previous belief that high population densities and farming were necessary for lethal plague epidemics to occur.

關於疾病的來源，研究人員強調爆發可能是由於人類接觸到野生土撥鼠，可能是透過食用生內臟引起。這項發現至關重要，因為它挑戰了先前認為必須有高人口密度和農業發展，才會發生致命鼠疫流行病的觀點。

The study proves that deadly plague outbreaks affected small, mobile hunter-gatherer groups long before the start of organized farming.

研究證明，在有組織農業開始之前，致命的鼠疫爆發就已影響了小型且流動的狩獵採集群組。

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。