An Interesting Fact...

Taking a break from all these theories, I thought I would share this particularly interesting fact that I stumbled upon during my research... approximately 65 million years ago, a huge meteorite impacted the coast of the Yucatan peninsula (home-to-be of the Maya, as you will hopefully know by now), coinciding with one of the largest mass extinctions on Earth. Scientists put two and two together and now believe that it was actually one of the major factors that led to the end of the dinosaur era (a result of the subsequent darkness and cooling from the meteorite ejecta). In fact, without this meteorite on Yucatan, the Earth wouldn’t be as we know it today, and humans may not have even existed!

The Defensive Systems Project

Under the umbrella of the ‘Vanderbilt Petexbatun Regional Archaeological Project’, the Defensive Systems project was initially created to investigate issues of warfare and fortifications that may have contributed to the Maya collapse. After seven years of surveys and excavations (1989-1996), some remarkable history of warfare in the late 8^th and 9^th centuries has been unearthed, particularly in the Petexbatun region, where the study sites were concentrated (Demarest et al., 1997).

What did they find?

• ·         Evidence of fortification systems, including defensive walls, for example the walls of the Plaza Group at Dos Pilas, a relatively small city (see the picture below)
• ·         Many of the walls seem to have been constructed in haste, showing signs of weaknesses that led to their failure
• ·         These were constructed in the Late Classic; those that have been precisely dated using ceramic markers, show ages between 760 AD and 830 AD.
• ·         They had baffled gateways or ‘killing alleys’ between walls, where enemies could be trapped and speared.
• ·         Hilltop fortresses were also later constructed, with more care and subsequently more success.

Although it clarifies many issues surrounding this controversial topic, this is reviewed as only a contributing factor and not an ultimate causality of the collapse.

The image above reconstructs what Dos Pilas may have looked like, before and after the defensive wall was put into place. 

But what could have caused the warfare?

It has been proposed that the rulers of major Maya centres, for example Tikal, Copan and Palenque, attempted to impose levies on their neighbours, due to stresses on the local economic base. This in turn could have led to warfare between rulers by the Late Classic period, who were fighting to acquire tributary domains where subsistence and luxury goods were concentrated. Agricultural failure and associated degradation may have led to a decentralisation of political authority, in turn leading to further instability and eventually abandonment (Foias and Bishop, 1997). Diamond (2005) actually makes a direct comparison between the rulers and 21st century CEOs, claiming that they were and are too concerned with short-term personal gain. 

Interestingly, another paper focusing on the Dos Pilas collapse (one of the first cities to collapse) found evidence from ceramics and hieroglyphics that the elite societies were the first to crumble, supporting the above theories of heightened competition within the elites. However, they even went as far as to reject the environmental degradation hypothesis to explain the collapse of this particular region (basically the opposite of papers that I have reviewed in former posts).

Is it likely that it did occur?

Numerous documentaries have also shown discoveries of defensive walls and hieroglyphic texts that potentially depict stories of bloodshed and huge battle, which are sure signs of warfare. The video below is the first of five parts of a documentary that looks into this in further detail.

In my opinion, it is most likely that there was some warfare, especially if there were food shortages etc. This probably weakened the societies further so that when they were faced with other challenges they were not able to survive, subsequently leading to their demise. But of course, that is just what I think from the evidence I have seen so far!

A small insight into the Maya culture

The video below is a reconstruction of the Ancient Maya ballgame that involved using the hips to hit a heavy rubber ball, with an aim to get it through a stone ring to score. Having actually watched this in real life (by real life I mean at a show in Mexico, and not by time-travelling unfortunately) I definitely think it is far more difficult to play than our regular football… However, one thing the video certainly doesn’t portray is the fact that losers were decapitated and sacrificed to the Gods!

This is one of the many examples showing how vibrant the society really was, but also how brutal it could be. Sacrifice was common throughout Mesoamerica, and it was no different for the Maya, who believed that the Sun would only function if nourishment in the form of human blood was provided (BBC, 2011). Their strict hierarchies and deeply spiritual beliefs may have played a role in their demise, as I shall review in the next couple of posts.  

Disease and Diet Doubts

While some skeletal remains show pathology that was caused by nutritional disease, which was expected to decrease fertility, there is no empirical evidence regarding such changes. Additionally, enamel defects (hypoplasias) in dental records of Pasión Mayan children were analysed by Wright (1997), as tooth formation is affected by nutritional stress and illness. However, no statistical differences were found throughout the Classic period, reflecting stability in overall stress loads in children. These results conflict with the ecological model of the Classic Maya collapse that assume elevated disease and deteriorating diet of both children and adults that I have discussed over the last few posts. The validity of the ecological models was also assessed by Wright and White (1996). They state that ecological models require the following health and dietary arguments to be true:

1. The Maya had a greater disease burden than other societies
2. The disease burden increased throughout their existence
3. Their diet must have changed consistently from the Preclassic and Early Classic to the Terminal Classic periods
4. There must have been an increasing social disparity in diet

In order to link these arguments, there must be a correlation between diet and disease. Yet, after looking at pathology and isotopic data, they couldn't find anything that consistently supported these criteria. They instead found diversity in both disease burden and diet, influenced by local environmental and political factors. Additionally, in contrast to the presumptions made by Santley et al. (1986), isotope analyses from the Pasión region actually showed that there was adequate protein in their diet and that diets were socially and regionally heterogeneous (Wright, 2006).

In light of this, both papers doubted ecological models as generalised explanations for the abandonment of Classic Maya sites in the southern lowlands. Wright (2006) stressed the importance of collecting as much biological data as possible, to build up a more reliable regional analysis and to avoid the inherent problems in interpreting small, fragmented data.

Additionally, despite the evidence of an increase of migration flows from the south to the north (Folan et al., 2000) - a common response to acute degradation and catastrophe - archaeologists have not discovered mass graves that may indicate epidemics or diseases that wiped out populations.

Just another thought...

I think it is also important to draw attention to the fact that a major part of the diet of the coastal populations included aquatic fauna that are rich in amino acids, something that was available in only relatively small quantities further inland. Thus, diets were probably better and agricultural failure wouldn't have led to such food shortages as it is thought to have done in the Lowland parts. Could this be a factor in explaining the differential collapse of the Maya area?  It is possible- the coastal areas did not experience a demographic crash to the same extent as the landlocked cities...

Food for Thought

Removal of forests for slope-land agriculture also destroyed habitats of many terrestrial fauna that were part of the Maya diet, including deer that were likely decimated in large numbers during the Late Classic times.  This was exacerbated by the fact that deer are not particularly abundant in tropical forests in the first place. It is suspected that the Maya occupying the forested (or not) Lowlands found it progressively difficult to source protein in their diet (Sharer, 1994).

Thus, they turned their focus on domesticated grains. The maize-based diet that they were so dependent on was rich in calories but lacked in other important nutrients. Although it was supplemented by beans, squash, tropical fruits etc, it was not a well-balanced one that included all nutrients and important amino acids that are essential for growth and development.  Furthermore, dietary deficiencies in zinc and iron were sure to have an effect on their population structure, especially through impairing successful reproduction (White, 1999). Santley et al. (1985) believe that the Maya had trouble replacing themselves, as their fertility rates declined and mortality rates increased, further aggravated by a lack of protein in their diet. Part of this is thought to be due to the nutritional stress placed on the people, and also because of the disease burden that they were faced with.

Even before the arrival of the Europeans and their accompanying illnesses, the pre-Columbian societies were constantly subject to infections and pathologies related to disease and parasites- this has been confirmed by evidence from human coprolites, mummified soft tissue and the remains of skeletons (Sharer, 1994). Complex ecosystems like tropical rainforests are often much greater hosts of infectious and parasitic organisms than simpler temperate ecosystems, and this has always been the situation.

Wilkinson (1995) proposed that a yellow fever epidemic migrating north from Brazil (where evidence of endemic varieties have been found) could have caused the Maya collapse. His speculations are based on similar patterns of the Maya decline to the declines of other populations who were exposed to yellow fever for the first time. Despite this, there is no direct archaeological evidence for this.

As with the crops like maize (discussed in my previous post), it is thought that the human population also became more prone to diseases due to agricultural intensification and settlement expansion. Such environmental changes would have led to an increase in insects (vectors) transmitting human pathogens and subsequently made infections more common. Additionally, through the reduction of other potential hosts, in particular the deer and other game hunted by the Maya, contact between vector organisms and the people was probably maximised. This would have further increased the likelihood of infections by vector-borne diseases, especially as the population grew throughout the Classic period (Folan et al., 2000). 

And it doesn’t end there. The vicious cycle between nutrition and infection would have further amplified effects of disease through positive feedbacks. For example, malnutrition would increase the severity of infections, which would then further exacerbate nutrition deficiencies and reduce immunity to future infections. The reconstruction of the Late Classic Maya food production carried out by Santley et al. (1985) supports these theories. They suspected that the low fertility rates and high mortality rates, especially among the very young and very old, led to an inevitable decline in population, as each age cohort decreased in size through time. 

One piece of evidence that I found particularly interesting was that they found a marked reduction in the mean stature of non-elites and elites (who were generally taller due to better diets and health) alike from looking at skeletal data. This coincides with the theory that together with agricultural failure and increased diseases, diets became poorer. 

An a-maize-ing theory?

As soil fertility is reduced by deforestation, the number of species present is also lowered. According to Santley et al. (1985), this resulted in a shift of concentration of weeds, insect infestations and plant diseases to the agricultural plots. Although this process is gradual and takes several years, it almost certainly would have helped reduce crop yields. This would have became a significant problem where fields were intensively cultivated and where monocropping was practiced, as the land became more susceptible to disease.

I found a paper that advocated the theory of the planthopper-borne virus (maize mosaic virus (MMV)) and its major role in the collapse of the lowland populations, predominantly focusing on the Peten area in northern Guatemala (Brewbacker, 1979). It argues the case fairly convincingly and draws on much more recent examples of how diseases to crops have caused agricultural abandonment, mass migration and population declines, such as the Irish Potato Famine. Even though I don’t think it was the primary cause of the collapse, it certainly seems that it caused food shortages large enough to affect population sizes. It also provides an explanation for the differential collapse, as the relative significance of pests and diseases was assessed and compared for various regions of the Maya area.

What is MMV and what are the effects?

• ·         A devastating virus that has a unique world distribution that just so happens to include the former Maya area.
• ·         It is transmitted by the corn planthopper, an insect specifically found in lowlands of the tropics.
• ·         Maize is one of two of its only definitive hosts thus it is only serious when maize is intensively cultivated throughout the year
• ·         It can reduce crops to less than 50cm in height and at its extreme, entire fields can be decimated
• ·         The Mv gene is the only known form of high level resistance (yet not immunity) of the virus. However, this gene has not been found to occur in maize grown in Central America, in contrast to other races of maize such as in the Caribbean.

It is hypothesised that the MMV originated in northern South America and was blown into the Peten across the Caribbean around the 8^th century. This facilitated the emergence of an epidemic among susceptible maize types (that lacked the Mv gene) grown by the Peten Maya.

It is suspected that this disease would not have affected the highlands in the south and west (where the corn planthoppers find it difficult to thrive), as well as areas that had longer dry seasons like in the northern Yucatan, as much as it did Peten.

This theory fits into the agricultural failure hypothesis that I discussed last week, since diseases like MMV can directly affect food production by decreasing yields and also indirectly, as it requires more labour to remove weeds and disinfest fields. The Maya agricultural system that was initially efficient, began to decline, as more people were required to work on the fields...you may think that this is not really a problem since they had an increasing population and therefore a larger workforce. Yet the amount of land suitable for crop cultivation was not unlimited- they soon began to run out.

However, it is important to consider a few points: firstly, the theory fails to explain how the northern Yucatan and the highlands also experienced abandonment and large population declines later on, especially since the MMV was not present in those areas. Secondly, it is not very clear on how exactly the MMV and the viruliferous leafhoppers were blown into the Peten, and whether it had also occurred previously, and if so, why was it only in the 9th century that the Maya civilisation collapsed. Such questions highlight the gaps of the hypothesis and so we must look to other suggestions of possible causes. 

Agricultural failure?

The Southern Maya Lowlands were comprised of a system of states, fragmented politically, but fused together by a common religion, writing system and a sophisticated culture. One of the initial ideas was that the disintegration of the political structure attributed to the abandonment of this forested interior (Lowe, 1985). While this is a viable option for contributing towards a collapse, it is not a sufficient explanation for causing such a major depopulation. Lowe’s model was soon dismissed by Santley et al. (1985) who believed that the collapse involved a systematic failure that was far more complex than just a breakdown of political hierarchies. They suggest it all began with agricultural production that eventually eroded not only the land but the economic base of the society...

It has been known for a long time that the Maya reached their peak during the Late Classic, and this has been increasingly supported by accumulating evidence, especially from ceramic and pottery studies. The Lowlands were densely occupied by peasant farmers and as population increased, the habitable landscape began to ‘fill up’ at a rapid speed (a fairly common process to many ancient civilisations dependent on simple food production). Exponential population rises occurred at large Maya sites, like Tikal, where the growth was curvilinear throughout the Classic period (Santley et al., 1985). It has been estimated that the population density per square km was 713 people (Puleston, 1973). Now this may not be as high as London’s density, but it is certainly much higher than that of Guatemala, which, according to the World Bank (2011), is 132 people per square km!

The continuous growth led to the simultaneous development of agricultural production across the Lowlands, accompanied by accelerated deforestation (confirmed from palynological evidence from the Peten, Guatemala, as well as various other sites in the Yucatan and Honduras e.g. Abrams and Rue (1988)). Santley et al. (1985) proposed that in order to increase subsistence yields, the Maya used spatially diversified cropping techniques, involving intensively cultivating slope-lands. However, repeated cultivation of slopes to maintain high yields is never a good idea, as the food production system will have a lower resistance to degradation processes and the associated erosion. This seems to be an important factor in reducing the efficiency of the agricultural system, but alone it cannot explain the nature of the Maya collapse.

And this is where deforestation becomes more important. As it is, soil fertility in tropical forests is relatively low, as nutrients essential for plant growth are either stored in the forest canopy or in the thin layer of leaf litter on the forest floor. This decaying layer of litter cannot accumulate if trees are continuously removed, and so forest clearance presents not only erosional problems, but decreases nutrients in the soil and in turn, reduces plant productivity. The exposed ground also becomes more prone to breakdown of soil structure and soil compaction, further augmenting erosion - as was the case in the Late Classic period. And even though it has been proven by numerous scholars, for example Dunning and Beach (1994) amongst others, that the ancient Maya used terracing in an attempt to reduce erosion, this was not practiced in all areas. Thus, the agricultural support base that much of the population became dependent on became progressively less resilient and unsustainable as the population continued to swell... Seems like a reasonable hypothesis so far!

What do we actually mean by collapse?

Unlike other complex societies, like those of the semi-arid Mesopotamia, the Maya civilisation did not see cycles of growth, decline and regrowth, but instead experienced a complete system collapse (as mentioned in my previous post) with many areas, in particular the Lowlands, completely abandoned. One of the most baffling thing seems to be that the Classic Maya had established a highly productive agroecosystem that fully utilised the surrounding tropical rainforests, supported by evidence of landscape modification and sustainable practices (Santley et al., 1986). So the question is, how did they not manage to survive?

There is a huge range of literature regarding the various theories on the collapse of the Mayas, with a long list of possible external and internal factors.  Some of these are summarised by Sharer (1994), who identifies tectonic activity, hurricanes, exceeding carrying capacity of the environment, epidemic diseases, internal revolt, economic collapse involving trade and competition, degradation of the environment (reduced soil fertility etc), beliefs in pre-determined cycles, and finally, climate change, as some of the main explanations.

However, since the first in-depth examinations into the Maya demise in the 1970s, there has been an increased realisation that the collapse was varied across the Maya area, occurring at different times and as a result of differing causes (Manahan, 2004). In fact, it has generally been agreed that the terminal Classic collapse occurred first in the southern and central Yucatan lowlands and that many of the northern lowlands declined a century later (Santley et al., 1985).  

Additionally, Lutz (2000) highlights the complexity in singling out causes and suggests that the interactions between population, development and environment are more intricate. The individual explanations have also been rendered inadequate as they lack systematic character (Lowe, 1985 in Santley et al., 1986). I will therefore try and review some of these theories from different points of views, including that of a demographer, climatologist and an anthropologist, to gain a holistic view on what really happened.

The Beginning of the End

What is exactly is Mesoamerica?

A concept developed by Paul Kirchhoff in 1943, Mesoamerica extends from central Mexico all the way down to Panama (i.e. modern-day Central America as shown on the map below) and comprises of five main geographical zones: the Maya area, the Oaxacan zone, the Gulf zone, West Mexico and the Central Highlands. Within this region existed many pre-Columbian cultures, each interrelated with similarities that have been spread through thousands of years of diffusion (Creamer, 1987). 

Map of Mesoamerica showing the Maya area (green) in relation to present-day countries.
Source: Mr Sanders' teaching blog on Mesoamerica!

The first Mesoamerican civilisation to emerge and begin to live in cities were the Olmec at around 1500 B.C., along a lowland strip of the present-day Mexican Caribbean coast. Since then, various cultures began to develop in a huge diversity of climates and terrains, many dependent on one another in terms of economy and trade (Folan et al., 2000). The timeline below nicely summarises when the most prominent societies existed, as well as highlighting any overlaps! Their history is conveniently divided into three significant periods that I will be referring to throughout my blog: Preclassic or Formative (2000 BC – 250 AD), Classic (250-900 AD), and the Postclassic (900-1519 AD). The main focus of the blog, however, will be on the Maya civilisation, considered to be one of the greatest cultures of the ancient world.

Timeline showing the dates for existence of the main Mesoamerican civilisations.
Source:  http://www.mesoweb.com/resources/timelines/crystal_timeline.html    

So who were the Maya?

With their sophisticated knowledge of astronomy, science and mathematics, and their great ability to produce magnificent urban infrastructures and fine works of art, the Maya led a settled lifestyle that rivalled their Mesoamerican counterparts (BBC, 2011). Since their emergence in the Early Pre-Classic Period, this lifestyle necessitated new concepts of territorialism and socio-political organisations, which they developed across the Maya area. They inhabited three main zones: the southern Maya highlands (including the mountainous regions of present-day Guatemala and in the state of Chiapas, Mexico), the central lowlands and the northern lowlands.  The lowlands cover parts of what are now southern Mexico, northern Guatemala and Belize (the Yucatán Peninsula), as well as western Honduras and El Salvador (Sharer, 1994).

There is a multitude of evidence showing that the Maya empire reached its peak during the Late Classic Period (600-900 AD), where large urban centres like Tikal and Palenque (which happens to be the background photo of this blog!) were established, facilitated by favourable climatic conditions. It is also believed that the population density was even greater than the population inhabiting the Maya area today (Peterson and Haug). However, this apex of material achievements and population size did not last long; development began to decline and their society imploded between 750 and 950 AD, leaving their magnificent cities and temples abandoned. The collapse and the exceptionally rapid depopulation have been of great interest to scientists and anthropologists alike for a long period of time and still present many puzzles (BBC, 2011).  

Despite this, there are still currently about seven million Mayans living in the Yucatán Peninsula, many of whom have retained their cultures and follow many practices and speak the language of their ancestors, whilst others have integrated into modern society (Eastmond et al., 2000).

The following video gives a good introduction to the Mayas and one of their most famous temples in Chichen Itza. It hopefully emphasizes how developed they really were (at their peak) for a Pre-Columbian society!