The Neolithic decline was a rapid collapse in populations between about 3450 and 3000 BCE during the

Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...

period in western

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

. The specific causes of that broad population decline are still debated. While heavily populated settlements were regularly created, abandoned, and resettled during the Neolithic, after around 5400 years ago, a great number of those settlements were permanently abandoned. The population decline is associated with worsening agricultural conditions and a decrease in

cereal A cereal is a grass cultivated for its edible grain. Cereals are the world's largest crops, and are therefore staple foods. They include rice, wheat, rye, oats, barley, millet, and maize ( Corn). Edible grains from other plant families, ...

production. Other suggested causes include the emergence of

communicable disease An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

s spread from animals living in close quarters with humans. The population increase between 5950 and 5550 BP (4000 to 3600 BC) that preceded the decline was catalysed by the introduction of agriculture, along with the spread of technologies such as pottery, the wheel, and animal husbandry. After the Neolithic decline, there were massive human migrations from the

Pontic–Caspian steppe The Pontic–Caspian Steppe is a steppe extending across Eastern Europe to Central Asia, formed by the Caspian and Pontic steppes. It stretches from the northern shores of the Black Sea (the ''Pontus Euxinus'' of antiquity) to the northern a ...

into eastern and central Europe, beginning approximately 4800 BP (2850 BC).

Plague

An ancient version of the ''

Yersinia pestis ''Yersinia pestis'' (''Y. pestis''; formerly ''Pasteurella pestis'') is a Gram-negative bacteria, gram-negative, non-motile bacteria, non-motile, coccobacillus Bacteria, bacterium without Endospore, spores. It is related to pathogens ''Yer ...

'' has come up from multiple skeletal studies throughout Eurasia, skeletons which have dated back to around the estimated periods of the Neolithic Decline. Additionally, genomes of the plague have been found as far back as 5,000 BP in areas such as Latvia and Sweden.

Discoveries in Europe

One 5,000-year old individual buried in Riņņukalns, Latvia, was infected with an early ''

'' strain, shortly after it split from its antecessor ''Y. pseudotuberculosis'' c. 7,000 years ago. A tomb in modern-day Frälsegården in Gökhem parish, Falbygden,

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

, contained 79 corpses buried within a short time of one another about 4,900 years ago. This discovery uncovered fragments of a unique strain of the plague pathogen ''

'' found in two individual's teeth. The strain contained the "

plasminogen activator Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) is en ...

gene that is sufficient to cause

pneumonic plague Pneumonic plague is a severe lung infection caused by the bacterium '' Yersinia pestis''. Symptoms include fever, headache, shortness of breath, chest pain, and coughing. They typically start about three to seven days after exposure. It is o ...

", an extremely deadly form of the plague which is airborne and directly communicable between humans. This strain of plague, researchers claim, alongside high demands of resources whilst living in close proximity to each other, would have allowed a pneumonic plague to quickly spread amongst inhabitants and wipe them out. In the gallery graves of the Neolithic Wartberg Culture, dozens or up to hundreds of individuals are preserved. A recent study by researchers from Kiel University ( Collaborative Research Centre 1266) have found that only two of 133 examined individuals were infected. As most were not, they conclude that no massive plague outbreak occurred. Moreover, they found the bacterium in bones of a dog. It is possible that dogs played a role in infections, but more research is required on this topic. Neolithic-era human teeth from Eurasia have also shown evidence of some of the oldest strains of ''

''. The ages of the skeletons identified between 2,800 and 5,000 years old, with seven of the one hundred and one individuals carrying similar sequences of the bacterium. Additionally, studies of the ancient strains discovered show these ancient strains lack the Yersinia murine toxin (ymt), which would have prevented the strains from using fleas as a vector.

Discoveries in Asia

A similar site was found in China in 2011; the site Hamin Mangha in northeast China dates back to approximately 5000 years ago and features a small structure filled with almost 100 bodies. Whilst there are several theories as what the reasons are for so many bodies in one location, such as a geological disaster or a ritual sacrifice, a plague is also considered as a hypothesis. In the case of the plague, despite being the weakest of the hypotheses, the placement of the bodies suggesting others carrying them in, alongside being intact before being burned, and the lack of artifacts alongside the bodies. Two other sites like these have been found in Northeast China: Miaozigou and Laijia, but archaeologists did not speculate as to the causal agent.

Counterarguments

Some studies, as those from the researchers from the Kiel University, have contested the hypothesis that the plague was responsible for the Neolithic decline. Analysis of the plague bacteria that infected a hunter-gatherer in Latvia during this period indicates that, unlike modern plague strains, the strain which afflicted this man was incapable of causing flea-spread bubonic plague and could only cause septicemic plague via a rodent bite or a largely non-contagious case of pneumonic plague, implying that the disease would have had difficulty spreading across vast distances in a short amount of time. The man identified in this particular case, after being studied, does not have a clear indicator of how much he was actually affected by the bacteria. Importantly, and supported by the results from the gallery graves of the Wartberg Culture, they do not see indications for a mass-outbreak.

Epidemiology

Gene studies of ancient ''Yersinia pestis''

Studies of the ancient variations of the bacteria have tried to show connections to the specific strain they studied and the more modern strands, such as ones during the Black Death. Studies in Sweden, on the Gok2 Neolithic ''Yersinia pestis'' strain, discovered it to be the basal to all known ''Y. pestis'' strains with the use of genome reconstruction, as well as containing plasminogen activators genes that would have allowed it to start a pneumonic plague. Other cases revealed a lack of ability to be able to use fleas as a vector of transmission; the case in Sweden contained Yersinia murine toxin which prevented the use of fleas, alongside a separate case studying late bronze-age bodies revealing the use of fleas in transmission would have occurred around the time after the collapse, being a few hundred years off.

References

Sources

* * Rasmussen, Simon; Allentoft, Morten Erik; Nielsen, Kasper; Orlando, Ludovic; Sikora, Martin; Sjögren, Karl-Göran; Pedersen, Anders Gorm; Schubert, Mikkel; Van Dam, Alex; Kapel, Christian Moliin Outzen; Nielsen, Henrik Bjørn; Brunak, Søren; Avetisyan, Pavel; Epimakhov, Andrey; Khalyapin, Mikhail Viktorovich (2015-10-22). "Early divergent strains of Yersinia pestis in Eurasia 5,000 years ago". ''Cell''. 163 (3): 571–582. * {{cite journal , last1=Rascovan , first1=Nicolas , last2=Sjögren , first2=Karl-Göran , last3=Kristiansen , first3=Kristian , last4=Nielsen , first4=Rasmus , last5=Willerslev , first5=Eske , last6=Desnues , first6=Cristelle , last7=Rasmussen , first7=Simon , title=Emergence and Spread of Basal Lineages of Yersinia pestis during the Neolithic Decline , journal=Cell , date=10 January 2019 , volume=176 , issue=2 , pages=295–305 , doi=10.1016/j.cell.2018.11.005 , pmid=30528431 , s2cid=54447284 , doi-access=free * Susat, Julian; Lübke, Harald; Immel, Alexander; Brinker, Ute; Macāne, Aija; Meadows, John; Steer, Britta; Tholey, Andreas; Zagorska, Ilga; Gerhards, Guntis; Schmölcke, Ulrich; Kalniņš, Mārcis; Franke, Andre; Pētersone-Gordina, Elīna; Teßman, Barbara (2021-06-29). "A 5,000-year-old hunter-gatherer already plagued by Yersinia pestis". ''Cell Reports''. 35 (13). doi:10.1016/j.celrep.2021.109278.

ISSN An International Standard Serial Number (ISSN) is an eight-digit to uniquely identify a periodical publication (periodical), such as a magazine. The ISSN is especially helpful in distinguishing between serials with the same title. ISSNs a ...

2211–1247. PMID 34192537. Eurasian history Decline Plague pandemics Societal collapse Kiel Archaeology