Part of the Amazon Thought to Be Uninhabited May Have Been Home to 1 Million People

Aerial photo of site Mt05, a circular enclosure (140 meter diameter) located on a hilltop.
Aerial photo of site Mt05, a circular enclosure (140 meter diameter) located on a hilltop.
José Iriarte

Depictions of the pre-Columbian Amazon basin as dense, inhospitable jungle with just a handful of indigenous communities scattered along the river may need to be updated. According to research published in Nature Communications, there were millions more people living in the rainforest prior to Spanish colonization than previously believed.

The Amazon is the largest rainforest on Earth, which poses a challenge to archaeologists exploring the history of the people who lived there. It's long been assumed that native Amazonians chose to avoid the heart of the forest and instead lived as nomads, never straying far from the major rivers. Some old estimates placed the population of the entire basin between 1.5 and 2 million people.

Thanks to satellites, researchers can now identify traces of long-gone settlements in the less-explored regions of Brazil without having to set foot in the jungle. A team of archaeologists from the University of Exeter used satellite imaging to find geoglyphs—large shapes dug into the ground, possibly for ceremonial purposes—in part of the Brazilian state of Mato Grosso that was thought to be uninhabited.

Geoglyphs and mounded ring villages.
Geoglyphs and mounded ring villages.
Nature Communications, Jonas Gregorio de Souza et al.

After pinpointing the locations of these earthworks, archaeologists visited this section of the southern rim of the Amazon to see some of them in person. At each of the 24 sites they set out to confirm, they found a real-life geoglyph on the ground. At one location, they uncovered charcoal and pottery dating back to 1410 CE. In all, they documented 81 new sites with geoglyphs.

The earthworks would have been carved into the dirt during a seasonal drought, allowing the architects to clear a swath of rainforest. Fortified villages were built in or close to the glyphs, with a network of roads connecting them to each other. The researchers created a computer model that estimated that a 154,000-square-mile patch of land could be home to the remains of 1300 geoglyphs and villages, only two-thirds of which have been discovered. In the late pre-Columbian period, the area, comprising just 7 percent of the Amazon basin, may have sustained a population of 500,000 to 1 million people, according to the researchers' models.

Aerial photo of site ZMt04, which contains the two largest enclosures that were identified.
Aerial photo of site ZMt04, which contains the two largest enclosures that were identified.
José Iriarte

Disease and genocide brought on by the European invasion destroyed most of those settlements, and they were later reclaimed by the rainforest. But evidence of their existence suggests that deforestation and development of the Amazon isn't a new phenomenon.

"Our research shows we need to re-evaluate the history of the Amazon. It certainly wasn't an area populated only near the banks of large rivers, and the people who lived there did change the landscape," researcher José Iriarte said in a statement. "Studies such as ours mean we are gradually piecing together more and more information about the history of the largest rainforest on the planet."

Homo Erectus Might Have Been Really Lazy

Shipton et. al,
Shipton et. al, PLOS ONE (2018)

Of all the human species that once roamed the world, only one remains—us. Why did our primitive cousins go extinct? For Homo erectus, something like laziness may have played a role, Cosmos reports.

A new study in the journal PLOS ONE explores the role that H. erectus's lack of drive may have contributed to its extinction. The international team of researchers based their analysis on an excavation of a paleolithic site in central Saudi Arabia, finding that the tools H. erectus made were of consistently lower quality than what tool makers in later periods used. Their tools were constructed with whatever material was easiest to get, rather than what would make the best tools.

And it wasn’t because better materials weren’t available. "At the site we looked at, there was a big rocky outcrop of quality stone just a short distance away up a small hill,” study co-author Ceri Shipton of the Australian National University said in a press release. “But rather than walk up the hill, they would just use whatever bits had rolled down and were lying at the bottom.” He added, “They knew it was there, but because they had enough adequate resources, they seem to have thought, ‘why bother?’”

A row of stone tools excavated from Saffaqah
Some of the stone tools
Shipton et. al, PLOS ONE, (2018)

Meanwhile, other hominin species, like our own Homo sapiens, were happily clambering up mountains to seek out better materials for their tools. Shipton suggests that H. erectus lacked the tendency toward exploration and curiosity that has helped our species thrive.

This “laziness,” combined with changes to their environment, was likely what did in H. erectus. As the humid environment around them became drier, H. erectus seemingly didn’t adapt: They didn't invent new kinds of tools to deal with the changing landscape, nor did they relocate or travel farther afield. The research team found the tools largely near dry river beds, suggesting that H. erectus neither progressed technologically nor modified their behavior for their altered habitat.

H. erectus did manage to walk upright as we do—a first in human evolution—and it was likely the first hominin to expand their habitat beyond Africa. But the combination of these two newly identified shortcomings may have contributed to H. erectus's demise.

[h/t Cosmos]

Intriguing New Theory Might Explain the Fate of Easter Island's Civilization

iStock
iStock

Standing up to 33 feet high and weighing 81 tons, the huge moai statues of Easter Island (Rapa Nui) are the most recognizable artifacts of a thriving civilization that peaked at the middle of the last millennium. For hundreds of years, Polynesian peoples lived on the small island 2300 miles west of Chile and developed a complex culture. By the 1700s, when Europeans first arrived, much of the society was decimated.

For years, scientists thought they knew why—but fresh archaeological evidence has provided an alternative theory.

The Journal of Pacific Archaeology published a paper [PDF] this week contradicting the commonly held belief that, in the 1600s, Rapa Nui's inhabitants descended into a Lord of the Flies–like era of infighting and violence as a result of dwindling resources. According to new research, the island’s population may not have devolved into barbarism. Instead, they were collaborating on toolmaking.

University of Queensland archaeologist Dale Simpson, Jr. theorized that the raw materials used in the carving tools would reveal clues about the dynamics of the community. He and his colleagues collected 17 tools found near the moai, including axe-like toki. Using a mass spectrometer to analyze the chemical composition of the tools and samples from stone quarries on the island, Simpson and his colleagues found that most of the toki came from a single quarry.

Simpson believes this is evidence that Rapa Nui's people had not fallen into violent conflict, but were instead sharing resources—or at least allowing one another access to a favorite quarry for tool production. If the islanders were split into factions, it’s unlikely that whoever was controlling the quarry would permit rivals to make use of it.

If accurate, it would join other recent theories that are drawing a revised picture of Rapa Nui's civilization. Explorers once described a surplus of spear-like objects presumably used for combat, but modern researchers examining the tools (called mata’a) in 2015 found that their surfaces were too blunt to pierce skin and were probably used for tilling soil.

While Simpson's take on the newly discovered carving tools is an intriguing theory, researchers aren't ready to rewrite history just yet. Other scholars, including study co-author Jo Anne Van Tilburg, point out that raw materials for the tools could have been seized by force or some form of coercion.

More research will be needed to see if Simpson’s new theory holds up. If it does, it would present a new wrinkle in the storied history of Rapa Nui.

[h/t Gizmodo]

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