Centuries of solitude on Easter Island may inform future space travel

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The famous Moai heads of Easter Island, Chile. (Unsplash/Thomas Griggs)

Lessons gleaned from hundreds of years of isolation on Easter Island may have as many implications for corporate research and development departments as they do for future colonies on Mars, according to the authors of a new study showing that Easter Island's population configuration promoted cultural diversity and retention of information.

The authors of the study — published Wednesday in PLOS ONE — employed computer modeling techniques to produce network analysis models and cultural transmission simulations of Easter Island, which led to the discovery of a counterintuitive result: The greater the number of subgroups in a population that have limited interaction with one another, the more likely it is that the population will retain beneficial cultural information. 

Rapa Nui is the indigenous name for both the island and the people of Easter Island in Chile. The island is best known for the hundreds of stone statues, called moai, located on every part of the island. At just 23 km at its longest point, Rapa Nui is small enough to traverse in under a day at a walking place, according to the researchers.

The remote island was colonized by Polynesian voyagers at some point between the 12th and 13th century A.D., and with other landmasses being thousands of miles away, the voyagers who arrived on Rapa Nui lived in complete isolation until Europeans discovered the island in 1722. 

Archaeological and historical evidence indicates that the island wouldn't have supported a large population, so Rapa Nui likely had a maximum of around 5,000 inhabitants, according to the study. 

In such an isolated place with relatively few people, one might expect that most inhabitants would have interacted with each other. What's curious about life on Rapa Nui, though, is that the population was organized into a series of distinctive subgroups, as demonstrated by archaeological and ethnohistoric evidence showing artifacts such as stone tools that were substantially varied across parts of the island; genetic analyses of skeletal remains also found significant variations. 

Carl P. Lipo, the lead author of the paper and professor at Binghamton University, said Rapa Nui is a place that "captures the imagination" — and it just keeps delivering surprises. 

For the present study, the researchers examined the effects of random drift, a concept with its roots in genetics, on the retention of cultural information on Rapa Nui. Random drift is the change in both genetic and cultural traits produced by underlying mechanisms through which variation is sampled and passed on through time. In other words, while some genetic and cultural traits are passed onto future generations, others vanish with time, which can cause evolutionary challenges in the retention of certain cultural information. 

One underlying mechanism that shapes random drift is population size. In small and isolated populations, the effects of drift theoretically lead to rapid loss of richness and diversity — that is, a rapid loss in the number of variants within a population and the distribution of variants within that population, respectively, according to Lipo and his colleagues. 

Cultural traits include the information that is passed down from generation to generation, especially in the absence of writing. On an isolated island with a relatively small population, this information is extremely important because it may contain facts that relate to survival on the island. 

"On an isolated island like that [Rapa Nui] with a finite population," Lipo said, "one of the challenges you have is just the act of talking to one another. And the fact that you can't talk to absolutely everyone means that information gets lost."

The researchers based their computer modeling on the island's distinctive spatial patterns, and they configured various ways in which these communities potentially interacted with each other. They then observed the effect these interactions would have had on the persistence of diverse cultural traits, including the retention of cultural information. 

The researchers didn't observe a loss in diversity and cultural information on Rapa Nui based on their modeling. Rather, they found that Rapa Nui's population structure actually increased the retention of cultural information across time and space — a rather counterintuitive result, but one that works out mathematically. 

"I mean, we've gotten people saying, 'Well, that's impossible,'" Lipo said. "But you look — it's math. It actually happens. … It's very counterintuitive."

The results of the modeling show that information retention is actually better when groups of people are configured in smaller, localized subgroups, which may have implications for future space travel. A colony on Mars would be incredibly isolated just like the inhabitants of Rapa Nui, but even more so since other Earthlings would be millions of miles away rather than just a few thousand. 

"Sort of socially, what would be the best structure for that community?" Lipo said. "How would you want to construct the colony and the social organization of that colony in order to maximize the chance that it will have the longest preservation, that it'll survive the longest … regardless of technical failures?"

While writing and technology mitigate the effects of random drift on information retention, evidence from Rapa Nui suggests that future space colonies should be formed in small, localized subgroups that promote interaction. 

"What's cool is that there's actually implications of this for businesses as well," Lipo said. For example, he said, employees of a research and development department may be sharing information among each other, but, "You're not maximizing the diversity, and there's a certain degree to which a company needs innovations."

"To maximize innovation, there's sort of a balance between bringing everyone together on a single idea and having enough variability to be able to come up with new stuff," Lipo said. "You want to structure it in such a way that you could encourage that diversity to persist in your company."

Lipo stressed how important it is to look back at ancient communities to see what humans today can learn; people in the present tend to have the perception that there is nothing to be learned from the way people lived in ancient times or from archaeological pursuits in general.

These past communities, though, are "the ones that actually made it," Lipo said. "Our future is uncertain. We don't know if we're going to do the right things. They did the right things, and we need to learn from it … The story is just phenomenal, that people did remarkable things, very counterintuitive to ourselves [and] our own way of thinking, but that made perfect sense on the island."

The study "Population structure drives cultural diversity in finite populations: A hypothesis for localized community patterns on Rapa Nui (Easter Island, Chile)," published May 12 in PLOS ONE, was co-authored by Carl P. Lipo and Robert J. DiNapoli, Binghamton University; Mark E. Madsen, University of Washington; and Terry L. Hunt, University of Arizona. 

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