A new international study led by Lund University examines what happened to population levels after the Kikai-Akahoya volcanic eruption in prehistoric Japan. The results paint a more complex picture than what has previously been believed.
The Kikai-Akahoya eruption took place in Japan some 7,300 years ago. At the time, Jomon foraging communities lived in Japan, surviving as hunter-gatherers.
"This eruption must have been devastating, exploding out of the sea bed with little warning. It battered the Japanese islands with powerful earthquakes and enormous tsunamis, and then blanketed the landscape with meters of volcanic ash," explains senior author Peter Jordan, professor in archaeology at Lund University.
The consequences of the eruption have been widely debated by archaeologists for decades. Some argue that it was an 'apocalypse' in which all human life abruptly ended closest to the epicentre, while others have started to argue for a local population survival, even in areas quite close to the eruption.
The research team found that both these versions - total collapse or continuity - were too simplistic.
On one hand, populations did decline, as ecosystems suffered and areas became uninhabitable. On the other hand, the researchers found evidence that humans were in fact resourceful in the face of dire circumstances. In some cases, the population actually increased in the period after the eruption.
Coping with sudden shocks
"The disaster caused major loss of life. However, survivors migrated, forged new social relations, innovated new kinds of economy, and appear to have found creative ways to exist and later thrive in the new post-disaster conditions," says lead author Enrico Crema, professor at Cambridge University.
According to Peter Jordan, the research demonstrates how unpredictable and complex the aftermath of a major disaster can be.
"This study helps in creating a deeper understanding of the contingent ways in which cultures and societies cope with sudden shocks and catastrophes. Even in the most impossible situations, survivors and communities have choices, however limited: they need to act and make decisions, they need to adjust, collaborate and find new connections and social networks," he concludes.
Population patterns identified by the study:
- Jomon forager populations were already in decline in southern Kyushu long before the eruption, and so the disaster hit a region that was already sparsely populated and only being visited by highly mobile groups.
- Populations were growing in northern Kyushu and this population growth trend actually continued right through the disaster and its aftermath, despite the massive and enduring damage to ecosystems. The authors suggest this resilient growth trend may be the result of 'refugees' moving out of the worst hit areas immediately after the disaster.
- Inland survivors appear to have moved away and clustered along northern coastlines, where marine ecosystems quickly recovered. Population growth may have been accelerated by new kinds of adaptation focusing on exploiting the abundant resources of the sea.
- The more distant areas of Japan had experienced population growth prior to the eruption, but saw demographic stagnation or even decline after the disaster. These far-reaching effects have never been identified before, and may be linked to short-term climate change triggered by the eruption, or to catastrophic tooth attrition among the deer and boar that the Jomon relied on for their food supplies (possibly a consequence of the animals grazing in ash covered landscapes), or to a suite of other volcanic impacts on human health and well-being.
