- Press Release Distribution

Study challenges popular idea that Easter islanders committed ‘ecocide’

Inhabitants found Ingenious ways to adapt to a harsh environment

Study challenges popular idea that Easter islanders committed ‘ecocide’
( Some 1,000 years ago, a small band of Polynesians sailed thousands of miles across the Pacific to settle one of the world’s most isolated places—a small, previously uninhabited island they named Rapa Nui. There, they erected hundreds of “moai,” or gigantic stone statues that now famously stand as emblems of a vanished civilization. Eventually, their numbers ballooned to unsustainable levels; they chopped down all the trees, killed off the seabirds, exhausted the soils and in the end, ruined their environment. Their population and civilization collapsed, with just a few thousand people remaining when Europeans found the island in 1722 and called it Easter Island. At least that is the longtime story, told in academic studies and popular books like Jared Diamond’s 2005 “Collapse.”

A new study challenges this narrative of ecocide, saying that Rapa Nui’s population never spiraled to unsustainable levels. Instead, the settlers found ways to cope with the island’s severe limits, and maintained a small, stable population for centuries. The evidence: a newly sophisticated inventory of ingenious “rock gardens” where the islanders raised highly nutritious sweet potatoes, a staple of their diet. The gardens covered only enough area to support a few thousand people, say the researchers. The study was just published in the journal Science Advances.

“This shows that the population could never have been as big as some of the previous estimates,” said lead author Dylan Davis, a postdoctoral researcher in archaeology at the Columbia Climate School. “The lesson is the opposite of the collapse theory. People were able to be very resilient in the face of limited resources by modifying the environment in a way that helped.”

Easter Island is arguably the remotest inhabited spot on Earth, and one of the last to be settled by humans, if not the last. The nearest continental landmass is central Chile, nearly 2,200 miles to the east. Some 3,200 miles to the west lie the tropical Cook Islands, where settlers are thought to have sailed from around 1200 CE.

The 63-square-mile island is made entirely of volcanic rock, but unlike lush tropical islands such as Hawaii and Tahiti, eruptions ceased hundreds of thousands of years ago, and mineral nutrients brought up by lava have long since eroded from soils. Located in the subtropics, the island is also dryer than its tropical brethren. To make things more challenging, surrounding ocean waters drop off steeply, meaning islanders had to work harder to harvest marine creatures than those living on Polynesian islands ringed with accessible and productive lagoons and reefs.

To cope, the settlers used a technique called rock gardening, or lithic mulching. This consists of scattering rocks over low-lying surfaces that are at least partly protected from salt spray and wind. In the interstices between rocks, they planted sweet potatoes. Research has shown that rocks from golf ball–size to boulders disrupt drying winds and create turbulent airflow, reducing the highest daytime surface temperatures and increasing the lowest nighttime ones. Smaller bits, broken up by hand, expose fresh surfaces laden with mineral nutrients that get released into the soil as they weather. Some islanders still use the gardens, but even with all this labor, their productivity is marginal. The technique has also been used by indigenous people in New Zealand, the Canary Islands and the U.S. Southwest, among other places.

Some scientists have argued that the island’s population had to have once been much larger than the 3,000 or so residents first observed by Europeans in part because of the massive moai; it would have taken hordes of people to construct them, the reasoning goes. Thus in recent years, researchers have tried estimating these populations in part by investigating the rock gardens’ extent and production capacity. Early Europeans estimated they covered 10% of the island. A 2013 study based on visual and near-infrared satellite imagery came up with 2.5% to 12.5%―a wide margin of error because these spectra distinguish only areas of rock versus vegetation, not all of which are gardens. Another study in 2017 identified about some 7,700 acres, or 19% of the island, as suitable for sweet potatoes. Making various assumptions about crop yields and other factors, studies have estimated past populations might have risen as high as 17,500, or even 25,000, though they also could have been much lower.

In the new study, members of the research team did on-the-ground surveys of rock gardens and their characteristics over a five-year period. Using this data, they then trained a series of machine-learning models to detect gardens through satellite imagery tuned to newly available shortwave infrared spectra, which highlights not just rocks, but places of higher soil moisture and nitrogen, which are key features of gardens.

The researchers concluded that rock gardens occupy only about 188 acres—less than one half a percent of the island. They say they might have missed some small ones, but not enough to make a big difference. Making a series of assumptions, they say that if the entire diet were based on sweet potatoes, these gardens may have supported about 2,000 people. However, based on isotopes found in bones and teeth and other evidence, people in the past probably managed to get 35% to 45% of their diet from marine sources, and a small amount from other less nutritious crops including bananas, taro and sugar cane. Factoring in these sources would have raised the population carrying capacity to about 3,000―the number observed upon European contact.

“There are natural rock outcrops all over the place that had been misidentified as rock gardens in the past. The short-wave imagery gives a different picture,” said Davis.

Carl Lipo, an archaeologist at Binghamton University and coauthor of the study, said that the population boom-and-bust idea is “still percolating in the public mind” and in fields including ecology, but archaeologists are quietly retreating from it. Accumulating evidence based on radiocarbon dating of artifacts and human remains does not support the idea of huge populations, he said. “People’s lifestyle must have been incredibly laborious,” he said. “Think about sitting around breaking up rocks all day.”

The island’s population is now nearly 8,000 (plus about 100,000 tourists a year). Most food is now imported, but some residents still grow sweet potatoes in the ancient gardens―a practice that grew during the 2020-2021 lockdowns of the Covid pandemic, when imports were restricted. Some also turned to mainland farming techniques, plowing soils and applying artificial fertilizer. But this is not likely to be sustainable, said Lipo, as it will further deplete the thin soil cover.

Seth Quintus, an anthropologist at the University of Hawaii who was not involved in the study, said he sees the island as “a good case study in human behavioral adaptation in the face of a dynamic environment.” The new study and others like it “provide an opportunity to better document the nature and extent of strategies of adaptation,” he said. “Surviving in the more arid subtropics on the more isolated and geologically old Rapa Nui was a heck of a challenge.”

The study was also coauthored by Robert DiNapoli of Binghamton University; Gina Pakarati, an independent researcher on Rapa Nui; and Terry Hunt of the University of Arizona.

# # #

Lead author contact:
Dylan Davis

More information:
Kevin Krajick, Senior editor, science news, Columbia Climate School/Lamont-Doherty Earth Observatory 917-361-7766



[Attachments] See images for this press release:
Study challenges popular idea that Easter islanders committed ‘ecocide’ Study challenges popular idea that Easter islanders committed ‘ecocide’ 2 Study challenges popular idea that Easter islanders committed ‘ecocide’ 3


Chilling discovery: Study reveals evolution of human cold and menthol sensing protein, offering hope for future non-addictive pain therapies.

Chilling discovery: Study reveals evolution of human cold and menthol sensing protein, offering hope for future non-addictive pain therapies.
Chronic pain affects millions worldwide, and current treatments often rely on opioids, which carry risks of addiction and overdose.  Non-addictive alternatives could revolutionize pain management, and new research targeting the human protein which regulates cold sensations, brings scientists closer to developing pain medications that don't affect body temperature and don't carry the risks of addiction.  Research published in Science Advances on June 21, led by Wade Van Horn, professor in Arizona State University’s School of Molecular Sciences and Biodesign ...

Elena Beccalli, new rector of Università Cattolica del Sacro Cuore, takes office on 1st July

Elena Beccalli will be rector of the Università Cattolica del Sacro Cuore on 1st July for the four-year term 2024–2028. After being appointed by the University's Board of Directors, which convened today, Thursday 20 June 2024, Professor Beccalli succeeds Professor Franco Anelli. She is the first woman appointed to this role in the history of our university.   The decision of the Board of Directors follows the appointment of Professor Elena Beccalli, Dean of the School of Banking, Finance, and Insurance ...

Pacific Northwest Research Institute uncovers hidden DNA mechanisms of rare genetic diseases

Pacific Northwest Research Institute uncovers hidden DNA mechanisms of rare genetic diseases
Seattle, WA — June 21, 2024 — Researchers at the Pacific Northwest Research Institute (PNRI) and collaborating institutions have made a groundbreaking discovery that could significantly advance our understanding of genomic disorders. Their latest study, funded by the National Institutes of Health[1] and published in the journal Cell Genomics, reveals how specific DNA rearrangements called inverted triplications contribute to the development of various genetic diseases. Understanding the Study Genomic disorders occur when there are changes or mutations in DNA that disrupt normal biological functions. These can lead ...

Empowering older adults: Wearable tech made easier with personalized support

(Toronto, June 20, 2024) A new review in the Journal of Medical Internet Research, published by JMIR Publications, found that community-dwelling older adults are more likely to continue using wearable monitoring devices (WMDs), like trackers, pedometers, and smartwatches, if they receive support from health care professionals or peers. The research team from The Hong Kong Polytechnic University, led by Dr. Arkers Kwan Ching Wong, reviewed data from 3 randomized controlled trials involving over 150 older adults. The evaluation showed that the interventions that focused on increasing awareness of being monitored and used collaborative goal-setting and feedback tools, such as the SystemCHANGE ...

Pennington Biomedical researchers partner on award-winning Long Covid study

Pennington Biomedical researchers partner on award-winning Long Covid study
Dr. John Kirwan, Executive Director of Pennington Biomedical Research Center, is serving as a co-principal investigator on the Pathobiology in RECOVER of Metabolic and Immune Systems, or PROMIS, study. The study has been awarded more than $802,000 by the National Institutes of Health to identify potential causes of Long COVID. “The PROMIS study will help us better understand what is driving Long COVID,” Dr. Kirwan said. “In the early days of the pandemic, Pennington Biomedical directed its resources to address the urgent health needs of our population. Now with estimates that more than 25 percent of people in the U.S. who had COVID have experienced ...

Cooling ‘blood oranges’ could make them even healthier – a bonus for consumers

Cooling ‘blood oranges’ could make them even healthier – a bonus for consumers
An orange teeming with antioxidants and other health benefits may be a shot in the arm for consumers and citrus growers, if the fruit is stored at cool temperatures, a new University of Florida study shows.   But it’s too soon to know if the so-called “blood oranges” are a viable crop for the Florida citrus industry, says Ali Sarkhosh, a UF/IFAS associate professor of horticultural sciences. Sarkhosh’s post-doctoral associate Fariborz Habibi explains further. “Although blood oranges typically command higher prices than other common varieties, such as navel or ...

Body image and overall health found important to the sexual health of older gay men, according to new studies

According to a National Poll on Healthy Aging, 93% of people in the U.S. between 50-80 years old report experiencing at least one form of ageism from other people. Internalized ageism is when a person believes ageist ideas about themselves, such as thinking they had a “senior moment” or thinking they are too old to learn new technology. Internalizing ageist stereotypes can impact older people’s mental and physical health, including sexual health. Various aspects of older adults’ sexual ...

Lab-grown muscles reveal mysteries of rare muscle diseases

Lab-grown muscles reveal mysteries of rare muscle diseases
DURHAM, N.C. – Biomedical engineers at Duke University have developed a new technique to better understand and test treatments for a group of extremely rare muscle disorders called dysferlinopathy or limb girdle muscular dystrophies 2B (LGMD2B). The approach grows complex, functional 3D muscle tissue from stem cells in the laboratory, creating a platform that replicates patient symptoms and treatment responses. In its debut study, researchers reveal some of the biological mechanisms underlying the characteristic loss of mobility caused by LGMD2B. They also demonstrate that a combination of existing treatments may be able to alleviate some ...

Primary hepatic angiosarcoma: Treatment options for a rare tumor

Primary hepatic angiosarcoma: Treatment options for a rare tumor
“[...] PHA is a rare yet aggressive mesenchymal tumor of the liver, which requires a multi-disciplinary approach to achieve the best patient outcomes.” BUFFALO, NY- June 21, 2024 – A new editorial paper was published in Oncoscience (Volume 11) on May 20, 2024, entitled, “Primary hepatic angiosarcoma: Treatment options for a rare tumor.” In this new editorial, researchers Gregory L. Guzik and Ankit Mangla from University Hospitals Cleveland Medical Center, University Hospitals Seidman Cancer ...

Research finds causal evidence tying cerebral small-vessel disease to Alzheimer’s, dementia

SAN ANTONIO, June 21, 2024 – Research led by in part by The University of Texas Health Science Center at San Antonio (UT Health San Antonio) finds that the most common cerebral small-vessel disease feature seen in brain magnetic resonance imaging is a primary vascular factor associated with dementia risk. Results of the major international study emphasize the significance of that feature, known as white matter hyperintensity (WMH) burden, in preventive strategies for dementia. “Our findings provide converging evidence that WMH is a major vascular factor ...


Samuel Pepys’ fashion prints reveal his guilty pleasure: Fancy French clothes

New genetic test will eliminate a form of inherited blindness in dogs

Cancer risk: Most Australian welders exposed to high levels of dangerous fumes

Two-in-one mapping of temperature and flow around microscale convective flows

Texas A&M engineers explore intelligence augmentation to improve safety

ORNL economist honored at international hydropower conference

UCLA selected by Centers for Medicare & Medicaid Services to test Medicare dementia care model

Fish adjust reproduction in response to predators

DDX41 and its unique contribution to myeloid leukemogenesis

Digital games on vaping devices could lure more youth to nicotine addiction

Cracking the code of hydrogen embrittlement

Long-term results from Testicular Cancer treatment are positive, study shows

EPA awards UMass Amherst nearly $6.4 million to help shrink the steel industry’s carbon footprint

Valentina Greco takes on new position as President of the ISSCR

Komen supports UVA Engineering researchers targeting ‘triple negative' breast cancer

Panel issues first guidelines to prevent anal cancer in people with HIV

Estimating rainfall intensity using surveillance audio and deep-learning

Targeting factors for chemoprevention and cancer interception to tackle mesothelioma

New snake discovery rewrites history, points to North America’s role in snake evolution

Large and unequal life expectancy declines in India during COVID-19

A study of 156,000 UK residents found that urban residents score the lowest in social and economic satisfaction and well-being

Global study by Hawaiʻi Institute of Marine Biology demonstrates benefit of marine protected areas to recreational fisheries

Researchers clarify how soft materials fail under stress

Revolutionizing the abilities of adaptive radar with AI

Plastic waste can now be converted to electronic devices

Health equity scholar Darrell Hudson named Health Behavior and Health Education chair at the University of Michigan School of Public Health

Research will establish best ‘managed retreat’ practices for communities faced with climate change disaster

Marshall University awarded grant to further fentanyl addiction research

Wash U researchers shine light on amyloid architecture

New dawn for space storm alerts could help shield Earth's tech

[] Study challenges popular idea that Easter islanders committed ‘ecocide’
Inhabitants found Ingenious ways to adapt to a harsh environment