Disturbances play a critical role in human population growth by increasing the resilience of surviving populations throughout history.
The study, published in the journal Nature, examines how quickly populations recovered from disturbances in the past – including extreme events such as volcanic eruptions, wars, the effects of colonialism and aridification – and what factors influenced their ability to withstand these challenges to recover from it. The study found that a single factor – the frequency of these events – increased these abilities.
The lead author of the study, Dr. Philip Riris, senior lecturer in archaeological and palaeoecological modeling at Bournemouth University, says: “We think that experiencing a disturbance causes a population to go through a kind of learning process that leads to them being better prepared for the next one.”
Furthermore, the results showed that these frequent population perturbations paradoxically helped keep long-term growth rates constant – suggesting that temporary or relatively local declines are a fundamental feature of humans’ long-term global success.
“It could also be that people with pre-existing technologies, adaptations, and social structures that were useful when a disruption occurred were better able to weather it, while others were unable to ultimately disrupt the cultural system “To steer towards these resilient properties,” adds Riris.
Population crashes and booms have historically lasted decades or centuries, with disruptions lasting an average of 98 years – and many even hundreds of years.
The researchers also found that the extent of disruption was strongly influenced by land use, with higher rates of population decline occurring in agricultural and pastoralist societies. However, the populations examined were also more resilient overall.
The international team of researchers from across Europe, the US and Asia, compiled and analyzed over 40,000 radiocarbon dates from existing studies and databases that showed evidence of population declines, for regions from Antarctica to the tropics.
While the impact of disruption on the present has been studied previously, this is the first systematic global comparison of the human ability to neutralize and recover from disruption over time.
“The resilience of past populations to frequent disturbances can reveal the complex relationships between environmental pressures and human adaptation over millennia,” says Dr. Yoshi Maezumi from the Max Planck Institute for Geoanthropology. “Understanding these dynamics not only enriches our understanding of past civilizations, but also opens up invaluable insights into overcoming current challenges.”
“Archaeology is uniquely suited to address these issues,” Riris concludes, “because no one else looks at human societies for as long or as systematically as we do. Our publication is a milestone in what we can expect about how societies respond to disturbances on a truly planetary and deep timescale.”