Easter Island population collapse never happened

Rapa Nui or Te Pito o Te Henua (the navel of the world), widely known as Easter Island is a remote landform in the southeastern Pacific Ocean. It is famous especially for its captivating culture, which has intrigued scholars and adventurers for centuries. Most famous are the colossal stone statues, the moai, standing as silent senturentinels to an era long gone.

Today a few thousand indigenous people live on the island. But it has been proposed that, before the Europeans came to the island in 1722, the population was much larger. The fate of the once big civilization in this remote location has been a topic of extensive debate among academics for centuries.

One dominating theory, the “collapse” theory, claims that the inhabitants of Rapa Nui depleted their natural resources such as wood to, for instance, build the moai, leading to a demographic and social collapse marked by famine, violence and even cannibalism.

Now, a genetic study published in Nature debunks this long-standing theory. The study was carried out by an international team of scientists and was co-led by Assistant Professor Víctor Moreno-Mayar from the University of Copenhagen and PhD student Bárbara Sousa da Mota and Associate Professor Anna-Sapfo Malaspinas from the Faculty of Biology and Medicine at the University of Lausanne in close collaboration with colleagues in Rapa Nui as well as in Austria, France, Chile, Australia and U.S. 

“Our genetic analysis shows a stably growing population from the 13th century through to the European contact in the 18th century. This stability is critical because it directly contradicts the idea of a dramatic pre-contact population collapse,” says first author Víctor Moreno-Mayar, Assistant Professor at the Globe Institute’s Section for Geogenetics, University of Copenhagen.

In case of a population collapse, the researchers would have been able to observe a less diverse gene pool in their analysis, simply due to there being a smaller population. However, when the team analysed the genomes of 15 Rapanui individuals who lived between 1670 and 1950, they found no signal of such collapse.

Not only is there no evidence of a population collapse before the Europeans arrived on the island, the data also shows that they were capable of even more formidable voyages across the Pacific than had been previously established, ultimately reaching the Americas.

The samples used in the study were obtained from the Natural History Museum in Paris, ensuring minimally invasive sampling methods out of respect for the cultural significance of the remains. Furthermore, when ongoing results were presented to representatives of the Rapanui community, the need to repatriate their ancestors was discussed as a central goal for immediate future efforts.  

“We have seen that museum archives contain mistakes and mislabels. Now that we have established that these 15 individuals were in fact Rapanui we know that they belong back in the island,” says Moana Gorman Edmunds, an archaeologist in Rapa Nui and co-author of the study.

A culture that adapted to change

Through their genetic analysis, the team of scientists has not only provided evidence against the collapse theory, but also emphasized the stability of the Rapanui society over several centuries until the disruptions caused by European contact in 1722. The “collapse” theory has been called into doubt by previous studies based on archaeological data and population dynamics arguments. This is the first time, however, that genetics has been used to tackle this question.

"While it is well established that the environment of Rapa Nui was affected by anthropogenic activity, such as deforestation, we did not know if or how these changes led to a population collapse," comments Anna-Sapfo Malaspinas, Assoc. Professor at the University of Lausanne and group leader at the SIB Swiss Institute of Bioinformatics, Switzerland, who co-led the study.

The researchers now believe the Rapanui adapted to environmental challenges that indeed occurred in the island between the 13th and the 18th centuries, which undermines theories suggesting resource mismanagement led to the societal collapse in the 16th or 17th century.

“The Rapa Nui landscape changed between the peopling of the island, which is around the 1200s, and the European contact 500 years later. However, the population stability throughout this time shows they were a resilient population capable of adapting to environmental challenges,” says Bárbara Sousa da Mota, a researcher at the University of Lausanne and co-first author of the study.

Long distance seafaring in the Pacific

In addition to challenging the "collapse" theory, the new study also found evidence that Rapa Nui was unlikely to be the last stop in Pacific voyaging. Although 3,700 km of ocean separate Rapa Nui and South America, the genetic analysis also showed that the Rapanui were in contact with Indigenous Americans before Europeans arrived in the island.

The team found that approximately ten percent of the Rapanui gene pool has an Indigenous American origin. But more importantly, they were able to infer both populations met before Europeans arrived in the island and in the Americas.  

"We looked into how the Indigenous American DNA was distributed across the Polynesian genetic background of the Rapanui. This distribution is consistent with a contact occurring between the 13th and the 15th centuries, " says Moreno-Mayar.

While our study cannot tell us where the Rapanui came into contact with Indigenous Americans, this might mean that the Rapanui ancestors reached the Americas before Christopher Columbus,” adds Malaspinas.

This result settles a longstanding debate on whether there was any pre-European interaction between Polynesians and Indigenous Americans.

“Personally, I believe the idea of the ecological suicide is put together as part of a colonial narrative. That is this idea that these supposedly primitive people could not manage their culture or resources, and that almost destroyed their people. But the genetic evidence shows the opposite. Not only is there no evidence of a population collapse before the Europeans arrived on the island,  the data also shows that they were capable of even more formidable voyages across the Pacific than had been previously established, ultimately reaching the Americas. So we can put those ideas to rest now,” says Moreno-Mayar.

Read the full study in Nature here: Ancient Rapanui genomes reveal resilience and pre-European contact with the Americas