Caral-Supe and the Emergence of Andean Civilization

Within the coastal desert of north-central Peru, a series of river valleys flow down from the towering Andes into the sea. In recent decades, archeological excavations in these river valleys have begun to uncover the remains of some of the earliest ancient cities within the Americas. The most numerous and well researched of these belong to a sprawling society called Caral-Supe, consisting of over twenty-five temple complexes. This culture is also known more broadly as the Norte Chico, a Spanish reference to their location on Peru's north-central coast.

Dozens of step-pyramids have already been unearthed across these sites. Many more still hold their secrets buried beneath the sands. The initial construction of these ceremonial complexes, beginning before 3000 BCE, predate the earliest pyramids of Egypt and are contemporary with the Ziggurats of Mesopotamia. They also occur over 1500 years before a similar level of social complexity arose within the Olmec of Mesoamerica. These discoveries reveal an extraordinary story about how a civilization first emerged within the New World, one which thrived for over a thousand years before its eventual collapse. Even after its subsequent decline, the cultural practices established here would lay the foundations for Andean culture through the millennia that followed.

Sections

• The Independent Invention of Andean Pyramids
• The Pre-Ceramic Enigma
• Was there a Marine Foundation of Andean Civilization?
• The Cultural Expansion: Caral-Supe, Norte Chico, Casma/Sechín & Kotosh
• The Roots of Andean Civilization
• Early Evidence of El Niño Cataclysms
• Sources

The Independent Invention of Andean Pyramids

When most people hear the word “pyramid” what tends to come to mind are the giant triangular, relatively smooth-sided pyramids of ancient Egypt that once served as tombs for ruling pharaohs. The pyramids of the New World differ both in terms of form and function. Those within both South America and Mesoamerica weren't constructed simply as tombs, although some did contain burials. Instead, they were primarily platforms for their rulers and shamanic priests to conduct ceremonies and for administration. Their elevated height served as power symbols of the higher social status of this elite class, and of their theocratic role as intermediaries to their deities. Many were built in multiple phases over centuries, building higher upon pre-existing pyramids within later phases of construction.

The predecessors to Andean pyramids began millennia before the era of Caral-Supe. They were simple earth mounds that served a ritualistic function. The earliest known of these is from Huaca Prieta, named for its rich dark soil. It was slowly constructed over centuries with successive layers of offerings of bones, shells, burials, and ceremonial fires. Its mound began to form seven thousand years ago. It grew for three thousand years to a height of 100 ft before it was finally abandoned (Dillehay et al., 2012). During later phases, this mound began to be reinforced with stone walls, and had rooms constructed on the upper platform with a ramp leading up from the base. It was beginning to resemble later Andean pyramids.

The pyramids of the Caral-Supe culture began roughly 3,000 BCE. Unlike the rocky Andes, this coastal region doesn't have quarries where megaliths can be sourced from bedrock. Instead, these were made mostly with bundles of smaller rocks tied together with reed ropes, cemented in place with mud as mortar. Offerings of clay figurines and sacrificial burials have been excavated from within these layers. They were built as a series of platforms with wide staircases leading up to numerous rooms built on top. Some were built in a single construction phase. Others would have periods of use and then another phase of construction would begin, filling in the prior rooms and creating a higher level. Temples and large residences were then plastered with clay and painted white, red or yellow. The amount of labor involved in constructing these would have been immense, requiring coordination of large groups of workers.

Commonly found in tandem with these step pyramids are circular sunken plazas, situated in front of the main steps leading up the temple. These would become a recurring architectural theme with later periods of the Andes too, such as at the site of Chavín de Huantar. What was the role of these sunken amphitheaters? We know that music was an integral part of their ceremonies. Within Caral's 'Temple of the Amphitheaters,' 32 flutes and 38 bugles were found, carved out of pelican and condor bones (Shady, 2006). Their purpose also appears to be closely tied to the pyramids themselves, likely serving as communal gathering places for religious practitioners before priests ascended the stairs to make offerings atop the temples.

At the top of these pyramids were central ceremonial rooms. Their inner walls contained niches, possibly as shelves for idol statues (as was common with later Andean cultures). And at the center of these rooms were hearths for fires. They were fed oxygen through underground ventilation shafts, to help fuel the intensity of the flame. Remnants collected from one of these air ducts contained the charred remains of bone, shells, plant material and various artifacts (Shady, 2006). These were likely given as sacrificial offerings (which again would be consistent with later cultures). This use of ceremonial fire atop these elevated platforms is reminiscent of the of millennia of fires that took place upon the mound of Huaca Prieta. What these continued themes demonstrate is that Andean religion had a very long trajectory, with some of their practices going back very deep into antiquity.

Some may look at ancient pyramids existing on different continents and wonder if they might have been connected by some single ancient parent culture. This hypothesis, referred to as hyper-diffusionism, was popular prior to the early-1900s. But a century later, after the invention of radiocarbon dating, that explanation has been shown to not align well with recent evidence. Firstly, many of these ancient pyramids began in various regions during very different time periods. And as shown by Huaca Prieta, within Peru the practice of pyramid building evolved very slowly, over thousands of years, beginning with simple mounds. It wasn't a practice that suddenly appeared fully formed, as one might expect with the abrupt arrival of a radically new culture. And as detailed above, both the structure and function of these pyramids was significantly different than those within ancient Egypt. These pyramids are clearly from a different culture. Nor do we have compelling evidence of other pre-Columbian cross-Atlantic contact, such as the introduction of domesticated foods or DNA.

Based on all this, it's safe to conclude that this style of Andean pyramid was a uniquely Andean invention, as was their broader culture (discussed in greater detail below). But why would diverse cultures around the world all decide to start building these triangular shaped structures? The simple answer here is that similar problems and similar constraints often lead to similar solutions. The motivation for building large temples may have been a universal one, to emphasize the importance of both their ruling elite and ceremonial sites. But this was a time well before steel-framed construction, where the primary building materials were mud and stone. Rather than constructing fragile vertical walls, the most obvious and stable way to build a tall structure so that it wouldn't collapse was to simply make it wider at the bottom and narrower toward the top. It's a pattern multiple cultures would have arrived at independently through basic trial and error, the design that is least resistant to toppling.

The Pre-Ceramic Enigma

It was an unassuming site called Aspero, on a coastal peninsula at the Supe River mouth, that would initially provide evidence for the ancient Caral-Supe culture. Aspero had been first surveyed by earlier researchers, including the famed German archeologist, Max Uhle, in 1905, and Gordon Willey in 1941. Being prior to the advent of carbon dating, both had observed the lack of pottery at the site and assumed that the culture that had lived here was a more recent technologically primitive fishing culture. It was an oversight that caused the significance of the site to be overlooked for decades.

The widespread abundance of ceramics throughout neolithic archeological sites generally reveals a lot about the culture that occupied a given site. And pottery is normally associated with domesticated foods, commonly thought to be a precursor to civilization. It's normally present wherever there are ancient agrarian settlements. So, its absence at Aspero erroneously indicated that there wasn't much of interest to be found. What they hadn't recognized was that the large mounds seen here were hiding pyramids underneath (Moseley & Willey, 1973). Their existing mental framework precluded the possibility that monumental structures could have been built by a culture that didn't demonstrate knowledge of ceramics. Instead, these were confused with natural geologic features. Moseley later quipped that "we're very much captivated by our own preconceptions, and what we see is what we get. But what we expect really determines what we see. If you don't expect there to be big platform mounds, you're not going to see them even if it's pretty obvious." (Moseley, 2010)

For decades, the Chavín of the later Early Horizon Period (900-200 BCE) had been regarded as the mother culture of Andean civilization. After coastal site of Huaca Prieta had been excavated in the 1940s (Bird et al., 1985), with its large pre-pottery earthen ceremonial mound, that story began to be rewritten. It resulted in a growing recognition of the cultural complexity beginning to arise in Peru during this Pre-Ceramic Period (8000-1850 BCE).

This shifting understanding of the Andean timeline led Michael Moseley and Gordon Willey to conduct another excavation of Aspero in 1971, approaching it with a revised interpretative framework. They remapped the site, which included three platform mound pyramids. They saw Aspero as evidence of a shift towards a sedentary culture, noting the intense amount of labor required to construct these temples. Subsequent radiocarbon testing at Aspero resulted in dates of 3000-1800 BCE, making it one of the earliest sites with monumental architecture within the Americas.

Among the few agriculture products recovered from Aspero were gourds, a relative to squash and pumpkins (Moseley & Willey, 1973). These were hollowed out to be used as floats for fishing nets, or as containers. Due to their hard shells, they would have been an effective substitute for clay pottery. The presence of these gourds on the Peruvian coast might explain why this culture was slower to adopt pottery than some other parts of South America. With the research conducted at Aspero, another important puzzle piece had fallen into place, beginning to reveal how civilization emerged along the Andes during the pre-pottery period. But the broader picture was still incomplete.

Was there a Marine Foundation of Andean Civilization?

The conventional understanding of how 'civilization' first arose in various locations around the world was that it first required the advent of agriculture. This was thought to provide a stable and predictable food supply, allowing for denser populations than what wild foods could typically support. However, at Aspero researchers were seeing an early site that demonstrated a shift towards greater social complexity, but which lacked extensive evidence of agriculture. Its sandy and salty coastal landscape wasn't particularly suited for farming, and Moseley hadn't seen widespread evidence of maize there, certainly not as a primary staple. Nor did he see widespread evidence of other domesticated food crops common at later sites, such as manioc and potatoes.

These initial excavations at Aspero instead revealed a culture that was heavily dependent upon marine resources for food. Midden piles were composed of mostly shellfish, but also contained fish, bird, sea lion, and whale bones. This isn't surprising considering Aspero's ideal coastal location, right next to one of the world's most nutrient-dense ocean habitats. The productivity of this stretch of coast is due to an ocean current of cold, low-salinity water, called the Humboldt Current, that moves up the western side of South America. This causes an upwelling of nutrients from the ocean's depths, feeding an abundance of phytoplankton, which serves as the foundation for the marine food chain. Bountiful schools of sardines and anchovies would have been a year-round source of protein.

During the 1960s, a number of researchers working independently had already begun to note this heavy dependence upon marine resources at coastal sites. Moseley & Willey's 1973 paper on Aspero added more weight to these observations. Then in 1975, Michael Moseley expounded upon the idea in a book, framing it as a broader hypothesis called "Maritime Foundations of Andean Civilization" (MFAC). At its core, the MFAC proposed that the abundance of seafood, not farmed crops, was the staple that laid the foundations for the later emergence of Andean civilization.

In addition, Moseley proposed that the development of agriculture at these coastal sites was primarily driven not by the production of food crops, but more importantly by the growing of non-food items to support activities related to fishing. Cotton, found at Aspero, was used in the production of nets, fishing line, and clothing. Totara reeds are known to have been used by coastal people for the production of primitive watercraft and mats. Gourds were utilized as containers, to carry things like fresh water or seeds, and were also used to make fishing floats.

The location of this site, on the coast near river mouths, was in close proximity to both marine resources and arable farmland upriver. Moseley thought that only after all the nearby farmland was being used would these coastal inhabitants have moved further up the river valleys. As distances grew, the community would have become more specialized between coastal fishermen and inland farmers. Seafood would be traded for cotton and other supplemental crops. Moseley further suggested that this social complexity, founded upon marine resources, had “pre-adapted” this society towards the later adoption of a more fully agriculturally based economy, including the construction of irrigation canals.

It was a compelling hypothesis, but was it true? When MFAC was first floated, the broader picture was still incomplete. Moseley was unaware of the many other Caral-Supe sites yet to be found, which would challenge his hypothesis.

The Cultural Expansion: Caral-Supe, Norte Chico, Casma/Sechín & Kotosh

In 1996, a veteran Peruvian archeologist named Dr Ruth Shady Solis began excavations at the site of Caral, located about 18m / 30km up the Supe River from Aspero. Like Aspero, it was another pre-ceramic site, but it was far grander in scale and complexity, resembling an ancient city. It had six large platform pyramid monuments and circular sunken plazas. It was surrounded by many residential structures. Some of these were larger multi-room houses, positioned close to the temples, made of stone, covered with plaster, then painted white. Other smaller residences on the outskirts of the city were made of sticks and packed with mud. This divergence in building style demonstrated the development of a social hierarchy, with a ruling elite that occupied the heart of the urban center.

The scope of the broader culture within the region was also revealed to be much more extensive. Shady's fieldwork in the 90s identified 18 different sites within the Supe Valley with similar architecture patterns, some comparable in size to Caral (Solis, 2006). Within this context, Aspero was now seen more as a satellite temple complex that was only a minor part of a much wider network of sites. This culture was dubbed the Caral-Supe culture, named after both the city of Caral and river valley where these many other sites were located.

In 2001, Shady invited Chicago-based archeologists, Jonathan Haas and Winifred Creamer to assisted her in radiocarbon dating Caral. Since the monuments were constructed with bundles of rocks tied with reed-fiber ropes, these ropes could be carbon dated directly to determine the age of the structures. The study yields dates ranging from 2627-1977 BCE. This was a few centuries after the establishment of Aspero, which had since been dated to 3055 BCE. The earlier dating of Aspero lent some credence to Moseley Maritime Foundations hypothesis. However, it was also clear that Caral and other inland sites eventually far outgrew their coastal predecessor.

Shady later had a falling out with Haas and Creamer, where she believed they had tried to take credit for her team's much longer field work at the site (Shady, 2005; Miller, 2005). Haas and Creamer had only briefly visited before being mailed the dating samples. Moseley took Shady's side in the dispute. The allegations eventually led to the Peruvian government launching an investigation and the Chicago Field Museum of Natural History rebuking Haas and Creamer for not giving proper attribution. However, Haas and Creamer resumed their work in the region and continued to make significant intellectual contributions. Their later surveys within the Fortaleza and Pativilca river valleys to the north revealed another 13 sites (Hass et al., 2005), and later surveys found more contemporaneous sites near Huaura River further to the south. This led Hass and Creamer to coin the term Norte-Chico (roughly translating to “a little north” in Spanish) to describe this culture's wider footprint across these four river valleys of Peru's north-central coast. While Norte-Chico is perhaps more accurate in terms of geography, Shady likely saw this rebranding of her work as another snub, as if it were diminishing the groundbreaking work that she led at Caral. The name Norte-Chico now more commonly appears within North American English-speaking sources, whereas Caral-Supe remains more typical within Peruvian sources. Here I use Caral-Supe to describe Shady's work and the sites of the Supe River Valley, and Norte Chico to describe the wider culture.

While not typically regarded as part of the Norte Chico, another site 120m/200km north, named Sechín Bajo, indicates an even earlier origination of some of these cultural traits. A circular sunken plaza was excavated here, similar to those of the Norte-Chico, but dated centuries earlier to 3,500 BCE (McDonnell, 2008). It's considered to be more in the Casma/Sechín Valley tradition. However, it does demonstrate how these cultural practices were spreading throughout a wider region. This architectural style may have originated within coastal river valleys, but by the end of the pre-pottery period it had expanded up into the Andes. The temples of Kotosh Religious Tradition also included sunken circular plazas and raised platform step pyramids with ventilated hearths (Shady, 2006; Toohey et al., 2024). These architectural patterns would continue to reverberate throughout later Andean cultures in the centuries that followed.

The Roots of Andean Civilization

What was revealed through these Norte Chico cities and temple complexes was a degree of social complexity that was far beyond what was previously thought possible during the Late Pre-Ceramic Period. Ruth Shady has described this culture as having achieved civilization (Shady, 2006). But what is meant by civilization? A problem with this term is that it's imprecise, where there's no single universally agreed upon definition. Nor is there a single point in time when it's suddenly achieved. As has been revealed within the Andes and in other parts of the world, it emerges via a slow process over many centuries. Some archeologists intentionally now avoid using the word, opting instead for more specific terms like urbanization. When it is used, it generally describes a common set of attributes that tend to arise in tandem. These include denser populations, the growth of cities with urban centers and monument sites, the development of trade networks, the specialization of labor, and the stratification of society into a social hierarchy, with an elite class acting as a centralized ruling government. By this definition, Shady's excavations have provided sufficient evidence to rightfully claim that Caral-Supe was a civilization.

Throughout the world, other examples of the emergence of civilization have also generally coincided with a shift towards agriculture. Within hunter-gatherer based lifestyles, people are entirely dependent upon the natural carrying capacity of their environments. If populations become too concentrated for too long, over-foraging in a single location, wild food sources can become exhausted and famine can result. This often leads to a more nomadic migratory pattern within these groups while searching for food. The shift towards agriculture increases the productive capacity of the land by focusing on more calorie dense, exploitable crops. It brought with it a more stable and predictable food supply. This in turn allowed for higher population densities and a more sedentary lifestyle, as is seen with the growth of cities. And with this sedentary lifestyle, with their social identities becoming more tied to a fixed location, people were able to spend more time constructing and maintaining local residential structures and temple monuments.

The Neolithic Revolution was, however, a very slow process. Plants became increasingly domesticated over thousands of years. Initially cultivated foods would have only supplemented wild foods, such as the rich marine resources of the Peruvian Coast. This brings us back to Moseley's Maritime Foundations of Andean Civilization hypothesis. Was it credible that civilization arose here based primarily upon fisheries, before agricultural foods were in use? Or did it arise following the more familiar pattern, with a growing dependency upon farming? Decades after it was first proposed, subsequent excavations of these Norte-Chico sites may have now helped to finally resolve this debate.

While Moseley had initially seen very little evidence of agriculture at Aspero, at the inland sites researchers found much more extensive signs of agriculture. Their inhabitants were cultivating a wide variety of edible plants, such as sweet potatoes, beans, squashes, avocado, guava, lucuma, achira, pacay, and chili peppers (Shady, 2006; Hass et al., 2005). A study examining microscopic traces in coprolites, pollen records, and stone tool residues was also able to determine that maize (corn) was in fact being eaten at these early sites (Haas et al., 2013), although it wasn't yet a staple food as in later periods (Pezo-Lanfranco et al., 2022). However, unlike seafood, corn can be stored for long periods, helping to weather periods of shortages of other fresh foods, so it would have been a valuable crop.

Irrigation was required to increase the agricultural productivity of these river valleys. Peru's coastal desert receives less than an inch of rain per year, so rainwater alone isn't sufficient to grow crops. Irrigation canals were constructed to channel water from the rivers towards their fields, whereas natural springs helped to supplement water during dry periods (Shady, 2006). This need for irrigation may also have been a factor in how social hierarchy and centralized administration of land began to develop (Haas et al., 2005). The location of these settlements along river valleys was critical in their success, since it ensured access to this vital resource for agriculture. This would have led to a concentration of power by those who had the most productive farmland and consistent water supply. As with the construction of their pyramids, the digging of these canals also required massive amounts of labor, with the ruling elite overseeing this effort.

Trade was also key to the growth of these cities. Even with the increased evidence of agriculture, at these inland sites marine resources were still the primary source of protein. Meat eaten at Caral was almost exclusively seafood, such as anchovies, sardines, clams, and mussels (Solis, Haas, Creamer, 2001a). However, Caral was situated 25km from the coast, a distance too far for the daily commute of fishermen to have lived there. And despite the abundance of cotton seeds, there was a complete absence of fishing equipment. In contrast, nets and fishing hooks were found at the coastal sites of Aspero and Bandurria. The large quantities of fish and shellfish consumed at Caral would have been brought and traded for the agriculture products of the river valleys, an exchange of protein-rich marine foods for carbohydrate-dense crops and cotton for nets and clothing. Further evidence of trade were findings of white potatoes at coastal sites (which only grow in the highlands), and shellfish within the highlands.

These coastal fishing communities and inland agricultural communities were complimentary and are an example of labor becoming specialized. Other types of trade work may have also developed. For example, a workshop was found at Caral containing beads of chrysocolla, quartz, spondylus and other stones, along with stone and bone tools (Shady, 2006). This suggests a specialized artisan class may have been emerging.

These inland cities, situated sporadically through valleys as parts of long trading networks, would have acted as important trading hubs for commerce. Wealth became concentrated among the elite who helped to orchestrate this trade. The first evidence of what appears to be a quipu has also been found at Caral. These are a series of tied strings that were later used primarily as an accounting device, still in use by the Inca at the time of the Spanish conquest. They may have been used for tracking trade transactions or tribute offerings.

The archeological findings coming out of these other sites seem to indicate that agriculture played a more significant role than previously believed. So, does this more complete understanding of their history still support the Marine Foundation Hypothesis? In 2004 Moseley wrote: “This can be framed as a hypothesis: the residents of Caral obtained more than 50% of their nutrition from the sea. The proposition is readily testable by dietary analysis of human bone chemistry. … If chemical analysis of human bone demonstrates that people received most of their calories from the sea, as is expected, then Peruvian fishermen can be credited for creating the earliest civilization in the Americas.”

A 2022 study attempted to answer that very question. Forensic Archeologists analyzed the bones of 52 individuals from Aspero & Caral. It was determined that a higher percentage of seafood was consumed at Aspero than at Caral, but plant food still constituted the majority of their diets (55%-68% in Aspero and over 70% in Caral), even from the early occupations (Pezo-Lanfranco et al., 2022). The percentage of seafood also seems to have declined at Caral in later periods, where improving agricultural techniques and improved domesticates may have been able to better scale up alongside a growing population than could wild fisheries.

So based upon Moseley's own test, while still a significant percentage, marine resources don't appear to have met his required threshold. Additionally, Haas had argued that if maritime resources were the key factor in the emergence of civilization here, then why aren't the largest sites located along the coast rather than inland, such as with Caral? (Miller, 2005). Instead, the more nuanced explanation appears to be one that is more in parallel with the emergence of other early civilizations around the world, where the adoption of agricultural foods ultimately still played the pivotal role.

While the original formulation of the Marine Foundations hypothesis hasn't fully stood up to scrutiny, we do now have a deeper understanding of the importance of marine-based foods during this period. Seafood does, nonetheless, still appear to be the primary source of Norte Chico diet protein, particularly in the absence of other domesticated animals as a source of protein. And marine resources undoubtable aided in the overall nutrition and food security of these communities. Many of Moseley's other interpretations have also still stood the test of time, such as fishermen trading seafood for cotton for their nets and gourds for their floats. A 2017 study excavating at the La Yerba estuary, on the south coast of Peru observed a contemporaneous fishing culture that began to urbanize only after the introduction of domesticated cotton from the north (Beresford-Jones et al., 2017). This community had been making fishing nets using relatively weak grasses. But after the introduction of cotton, such as that used by the Norte Chico, it appears as though they were better able to exploit the ocean with higher quality nets. Only after this point, with an intensification of marine resources, did monumental architecture begin to appear at La Yerba. These researchers present this as a more refined version of the Marine Foundations hypothesis, which they personally saw as “more persuasive than ever.” The debate goes on.

Early Evidence of El Niño Cataclysms

The Caral-Supe/Norte Chico culture flourished for over a thousand years, until roughly 1800 BCE, when it began to decline. Its many temple complexes, once serving as important religious and administrative centers, were eventually abandoned. What led to the end of the culture that had thrived here for so long? Another pre-ceramic coastal site called Vichama provides us with clues.

Vichama is located on the coast near the Huaura River (towards the southern boundary of the Norte Chico region). Its name derives from a precolonial myth about Vichama and Pachacamac, two sons of the Sun God. The legend relates to human sacrifice nourishing the earth, resulting in the first cultivation of various crops. It also tells of how people were turned into stone monoliths, or huancas, such as those found throughout these Norte-Chico sites (Creamer et al., 2017).

The Vichama archeological complex was constructed towards the end of the Norte-Chico culture, around 1800 BCE (TV Perú / Shady, 2022). It's unique from other Norte Chico sites due to the higher degree of preservation of its clay plastered walls, and most notably, because of its sculpted murals. Ruth Shady has described these friezes as capturing the collective social memory of the people who once lived here. Deciphering what they symbolized to these ancient people is often challenging. However, those at Vichama do seem to share a common theme, one which correlates well to the broader archeological record.

Upon the main temple pyramid is a mural with a row of people, possibly dancing, but who are holding open their empty stomachs, removing their heads, or are depicted upside-down. At the ends of these rows are downward pointing fish, which a guide at the site suggested symbolized declining catches of seafood. A lower level features more emaciated skeleton-like figures, with exposed ribs and sunken stomachs, with their eyes closed, possibly to represent them being deceased.

At the level above these figures is a square plaza, which has a mural of an anthropomorphized toad being struck by a lightning bolt. Toads are associated with rain in Andean mythology, so this may represent a concern over rain, either too little or too much (more on that soon).

A third mural at the site was only more recently discovered (it was unfortunately still undergoing excavation during my visit). It shows curving snakes, which are commonly interpreted as winding rivers within Andean art (perhaps due to Anacondas living in rivers). The heads of these snakes are arriving at what's been suggested to be an anthropomorphized seed taking root. This mural is thought to represent river waters irrigating crops.

What was the deeper meaning that Vichama's murals were illustrating, particularly the emaciated skeleton figures atop their temple? The images appear to be related to agriculture, fish, rain, and a period of famine. Knowing some more about coastal Peru's unique geography and climate will help to fill in some gaps of the story.

As detailed above, normally the Humboldt Current brings cold water and air up the western coast of South America, contributing to its productive fisheries. This cold air, in conjunction with the giant eastern climatic barrier of the Andes, is also what keeps this desert region so dry. However, every few years Pacific Ocean weather patterns temporarily reverse due to weakening trade winds. This allows warm equatorial water to flow eastward, increasing surface water temperatures along the coast. These are referred to as El Niño Southern Oscillation (ENSO) events. Typically, El Niños occur every 3-4 years, and tend to be relatively mild. But their strength can vary greatly, sometimes radically shifting regional weather patterns with devastating consequences.

These extreme weather events impact the food supply in multiple ways. Firstly, they severely reduce the availability of seafood. The warm water concentrated at the ocean's surface disrupts the circulation of the Humbolt Current, preventing the upwelling of nutrients and leading to a decline of plankton. This impacts the entire food chain, including fish and other sealife. El Niños are commonly associated with massive die-offs of bird chicks, as their parents are forced to flee elsewhere in search of food (Mann, 2018). Sea lions and other marine life are also known to migrate elsewhere during these periods. For a society that derived most of its protein from seafood, the collapse of this major food source would have significantly contributed to periods of famine.

The second major impact brought by extreme El Niño events is severe flooding, dramatically affecting agriculture. As the warm, humid air is pushed up the mountainous Andes, it compresses moisture out of the clouds, resulting in torrential downpours. The hard exposed dirt in this desert environment, mostly devoid of vegetation except within river valleys, does little to slow floodwaters. These floods deposited large slurries of debris along the riverbanks, creating ridgelines at coastal beaches. This shifted the hydrology, causing low lying valleys to flood. An excavation of an ancient residence near Aspero found evidence of this, showing a distinct layer of deposited silt with a rippled pattern (Sandweiss et al., 2009).

These flood sediment ridges were carbon tested to determine their dating. Significant landscape changes started around 2000 BCE, with particularly bad flood events occurring 1600-1800 BCE (Ortloff, 2022). This dating coincides well with the Norte Chico's decline. The floods also stripped precious topsoil from agricultural land within the river valleys, while inundating fields with sand. They would have significantly impacted vital irrigation canals. This devastation caused agriculture activity to shift to higher elevations, onto more protected but less-productive plateaus. Flooding rivers also ejected sediment into coastal waters, which was deposited over mollusk shell beds, further impacting fisheries (Ortloff, 2022). In addition, the coastal ridgeline that was created resulted in an increase of sand blowing across the landscape, inundating coastal communities (Sandweiss et al., 2009).

This loss of both productive farmland and reduced availability of seafood meant that the food supply would have been much more limited and no longer able to support large populations. During these extreme El Niño periods, the carrying capacity of the environment became severely restricted. And for an ancient people who believed that natural disasters emanated from supernatural deities, this environmental degregation would have also called into question the social power structure of the ruling theocracy. By 1500 BCE most of the temple complexes in the region show signs of an almost complete abandonment (Ortloff, 2022). It was a major collapse of the Norte Chico/Caral-Supe civilization. Some of these valleys wouldn't be repopulated with cities again until modern times (Sandweiss et al., 2009).

There are some within alternative-history circles, or those with a biblical understanding of history, that often conflate these South American flood events with their belief in a global mega-flood, an event that they claim happened thousands of years ago. While it is true that many cultures around the world do have flood mythologies, it should be noted that early agrarian societies tended to originate within river valleys. In good times these valleys make for productive farmland. But they also concentrate water during heavy rains, and so are prone to suffering from periodic extreme floods that can breach riverbanks. It's natural that stories of floods would be commonplace around the world when such flooding itself is commonplace.

The archeological and geological record of coastal Peru presents a long history of this periodic flooding. They are also seen impacting later cultures too, such as the Moche in the 6th-7th century and Chimú in the 11th century CE. El Niño floods have continued into modern times. The 2017 El Niño left hundreds of thousands of Peruvians homeless. In this context, it's clear that these recurring Peruvian El Niño flood events shouldn't be seen as supporting the narrative of a single global mega-flood. It's understandable to look for patterns and commonalities when learning about ancient history, as also noted within the prior discussion of pyramids, ziggurats, and mounds. And yet, upon closer inspection, we again see that the Peruvian Andes is a distinct region with its own distinct history.

The many discoveries leading to our present understanding of the Caral-Supe / Norte Chico culture have provided us with profound insight into the early development of civilization in South America. While at times contentious, the groundbreaking research of the many archeologists involved in this effort has ultimately uncovered a much more complex history. Their findings toppled previous notions of how, when, and where early Andean civilization developed. We now know this occurred within coastal Peru's Pre-Pottery Period.

The ancient inhabitants of this region, by skillfully intensifying both agricultural and maritime resources, managed to thrive for over a thousand years within a challenging desert environment. Nearly five thousand years after the initial construction of their cities, their pyramid complexes are re-emerging from the sand to once again stand as testament to that adaptability. While their eventual decline might serve as a poignant reminder of the vulnerability of human societies to environmental changes, the civilization they pioneered was a monumental achievement, ultimately influencing subsequent Andean cultures through the millennia that followed.