Jungle
Page 15
The Llanos de Moxos area in the Bolivian Amazon perhaps best encapsulates the complete shift in understandings of the tropical rainforests of the Amazon Basin as centers of early plant cultivation. Today this sweeping region, characterized by a highly seasonal climate, sees significant portions of its “savannah-like” landscape flooded for much of the year. However, all is not as it seems. When a team of scientists led by Dr. Umberto Lombardo from the University of Zurich cast their eyes over high-resolution satellite data for the area, as well as computer-based models of how the terrain differed over space, they identified some unusual alterations to the surface of the land. Together they pinpointed over 6,600 sites that they call “forest islands”—raised, forested patches that, when visited by archeologists, also revealed clear traces of human presence and enrichment of soils with their waste. These human-made mounds would have provided areas safe from the annual flooding—areas put to good use by past human populations. Publishing in the renowned journal Nature, Umberto and his colleagues demonstrated that the soils of these “forest islands” revealed a long record of human manipulation of plants. Heart-shaped manioc phytoliths dated to 10,350 years ago, while spherical squash phytoliths dated to 10,250 years ago. Whether these plants were fully domesticated by this time or whether this was just the beginning of a long process to produce crops that act as staples for populations of the Amazon Basin today remains unclear. However, as study coauthor Professor José Iriarte of the University of Exeter argues, “This evidence, alongside the tropical forests of south-western Mexico, undoubtedly means that this region should be considered, alongside the heavyweights of China and the Middle East, in global discussions of plant cultivation and domestication following the last glacial period.”12
Turning our attention to the tropics of the “Old World,” South and Southeast Asia have also produced a number of domesticated plants and animals found in many of our kitchens today. In the humid state of Odisha in India, a mixture of environments, from sweeping riverbanks to tropical forests, seemingly provided the setting for humans to locally domesticate Indian varieties of rice, millet, gourds, and types of cucumber. Okra, a plant familiar to anyone who has eaten a number of native Indian dishes, was also domesticated in this part of India. Delicious, succulent mangoes originated as a tree crop in the tropics of Southeast and South Asia. Meanwhile, black pepper, which flavors a vast variety of cuisines and dishes around the world, from morning eggs to spicy “curry” dishes, owes its domestication to cultivators inhabiting the tropical coastlines of Kerala in southern India. Cinnamon, another crucial spice for budding and professional chefs alike, appears to have been cultivated slightly further south, in Sri Lanka. The first mention of this spice 5,000 years ago indicates that local merchants exported it to ancient China and, later, to the classical Mediterranean world. It even makes an appearance in the Bible. Finally, although the exact origins of domesticated citrus precursors of the lemon remain hazy, and citrus fruits are notoriously difficult to keep track of archeologically, it seems most likely that they were domesticated somewhere in Southeast Asia, within their wild range of growth. Although, in all of the above cases, dating the exact arrival of a “domesticated” form of these plants is immensely challenging, relying on rough, modern genetic “clocks” and fragmentary remains left in tropical soils, we can posit that much of our food and drink would taste very different without these tropical bounties shaped by prehistoric human hands.13
Figure 7.2. Forest islands at Llanos de Moxos, Bolivia. Umberto Lombardo
Tropical forests may also seem unlikely homes for domesticated animals, but they played a hand in the appearance of two of the animals most relied upon by farmers around the planet today. Humans use water buffaloes more than any other domesticated animal, with the large populations of Asia relying on these hulking beasts for milk, yoghurt, and cheese. The two “types” of these slow but strong beasts, the “river” and “swamp” buffaloes, today wallow in waterlogged settings flanked by tropical and subtropical forests, consuming freshwater plants. Although their origins remain obscure and they have received little attention compared to Euro-American cattle, deliberate human herding of these bovids seems to have started around 5,000 years ago in India and 4,000 years ago in Southeast or East Asia. The chicken represents perhaps a still more secure tropical forest domesticate. Humans have morphed this bird into one of the most common animals on the planet today, with a population of over 25 billion. While you would not know it to look at them, they are descended from the red “jungle” fowls that have long stalked the tropical forests of Asia. A recent genetic study, based on the genomes of 863 chickens and a sampling of all species of wild jungle fowl, shows that the domestic chicken emerged from a subspecies of jungle fowl that lives in the tropics of southern China, Thailand, and Myanmar. After their domestication, these poultry were moved throughout Southeast and South Asia, further interbreeding with other jungle fowl species. While its history is complex, the chicken, which forms the basis of many a fast-food meal, sandwich, or Sunday lunch today, undoubtedly originated in the tropics.14
ALL OF THE above examples refer to the domestication of plants and animals within tropical forests, as hunting-and-gathering communities living in these environments gradually increased their involvement in the natural world to become food producers. In many cases, as at Kuk Swamp, this meant that domesticated plants and animals supplemented existing consumption of wild plants and animals as part of diverse economies that operated on the basis of clear local knowledge of tropical forest life cycles and tolerances. In the Amazon Basin, for example, prehistoric farming practices represent a sophisticated early form of agroforestry. “Gardens” of manioc and, when it arrived, maize were cultivated at the same time as managed, but intact, forests were used for fruits, nuts, and wild animals. Wild Muscovy ducks and freshwater turtles may even have in some way been “herded” as part of these varied approaches to landscape management. Although, as we will see later, this increasingly intensive food production shaped the soils, geography, forest structure, and biodiversity of the Amazon Basin, it seems to have had a relatively limited impact on overall past tropical forest cover. Similarly, diverse and sustainable strategies of food production have also been documented in early and middle Holocene New Guinea and island Southeast Asia. But what happened in prehistory when farming, particularly in the form of field-based agriculture, was introduced into tropical forests from the outside? Did it lead to massive deforestation, landscape degradation, and cultural shifts, as it does today, as people tried to force their way of life onto these environments? Or did past societies manage to adapt external practices to local situations?15
A classic example of a more “agricultural” introduction into tropical forests is the spread of the type of rice most common around the world today. Genetic and archeobotanical research suggests that rice emerged in the Yangtze River basin in southern China around 9,000 years ago from a wild, wetland grass. From here, the Oryza sativa japonica rice subspecies diversified and moved both north, to the edge of its lowermost temperature tolerance, and south, toward the tropical forests of South and Southeast Asia. By about 4,000 years ago Oryza sativa japonica had reached India, adding to the indigenous forms of rice (Oryza sativa indica) already cultivated on the Ganges floodplain since 5,000 years ago, as well as mainland and island Southeast Asia. Here, rice, although deriving from a wild subtropical grass that requires significant rainfall, also must grow in the open, seemingly necessitating forest clearance if it is to be cultivated. This is particularly the case as more intensive “wetland” farming techniques were applied to rice from around 6,000 years ago in China in order to harness its energy potential, with terracing and rice paddies requiring significant alterations to the landscape and year-round waterlogging. Foxtail millet was also domesticated in China and became rice’s partner in crime as it moved southward as part of a package. As this crop generally prefers drier, open conditions, it would have placed further demands on cultivated land, particul
arly in the tropics.16
Unsurprisingly, the expansion of these crops into the tropical forests of Southeast Asia has generally been linked to large-scale forest clearance, resulting in the dramatic landscapes, such as the UNESCO-protected Ifugao rice terraces of the Philippines, that tourists flock to see today. Nevertheless, pinpointing their arrival has been challenging given that miniscule rice and millet grains are rarely preserved in archeological sites, and the diligent sieving required is only a fairly recent archeological practice. The earliest archeobotanical evidence for rice in mainland Southeast Asia dates to 4,000 to 3,500 years ago in the coastal portion of Thailand, with rice and millet reaching further inland by 3,000 years ago. In island Southeast Asia, the first evidence for rice dates to roughly the same time in Borneo, although some of this evidence is based on impressions left by pieces of rice in pottery. In areas with drier, seasonal tropical forests, there is evidence of burning to clear the way for these new, productive crops. That said, destruction was not guaranteed. In the lowland evergreen rainforests of mainland and island Southeast Asia, rice and millet farming was often combined with the ongoing cultivation of yam and taro tubers, as well as starchy sago palms, in smaller, more open forest patches. Alternatively, farming was ignored altogether by forager communities more interested in harnessing the local productive resources than investing energy to clear forests that had long provided them with shelter and food.17
Figure 7.3. Image of the UNESCO-protected Banaue rice terraces in Ifugao on the island of Luzon in the Philippines. These terraces likely have ancient precursors in the region that may have been used for the growth of taro prior to rice (see also Chapter 10). Getty Images
The deep forests of Central Africa are another important setting where we can explore what happened when incoming agricultural strategies adapted to local tropical conditions. The arrival of farming in this part of the world has often been linked to the so-called Bantu expansion, a migration of populations from West Africa that all speak languages within the same Bantu family. These people are thought to have brought the crop pearl millet with them as well as iron technology, sweeping southward through the African continent, all the way to South Africa, during the late Holocene (4,200 years ago to the present). Pearl millet is an arid-adapted grass that appears to have been domesticated in the river valleys on the southern edge of an expanding Sahara (just after its last “green” phase) around 4,000 years ago. It then expanded south, moving with Bantu-speaking populations and reaching northern Ghana by 3,500 years ago, the rainforests of Cameroon by 2,500 years ago, and the Democratic Republic of the Congo in the last 2,000 years. Due to assumed vulnerabilities of this crop to warm and wet conditions, scientists have associated its appearance with the dramatic late Holocene “rainforest crisis” in Africa around 2,500 years ago, when lowland rainforest seems to have rapidly retreated in favor of more open settings. Some scientists believe this change was a climatic phenomenon; others think it was actually caused by iron-wielding, Bantu-speaking farmers who indiscriminately cleared the landscape to promote the production of their favorite food source.18
Growing evidence suggests, however, that disastrous forest clearance need not have accompanied the arrival of pearl millet in the Central African tropics. Scientists undertaking experimental farming today have shown that this crop can be effectively grown in wet, humid plots next to rainforest. Bantu-speaking communities and pearl millet also continued to move and occupy different tributaries of the Congo River long after the end of the supposed crisis. Interestingly, the first pearl millet in Ghana is joined by plants like oil palm and yams, which had their origins in African tropical forests, suggesting a more mixed strategy. As we will see in Chapters 13 and 14, oil palm is now part of a global economy that fuels products as diverse as nut-based chocolate spreads and face creams. Local contributions also seem evident in the use of groundnuts, castor beans, and gourds, which were also domesticated in the tropics of Africa and continued to provide important food sources from these environments. In the absence of evidence for pre-Bantu communities, at least in the western Democratic Republic of the Congo, these combinations of resources seem to show rapid farming ingenuity and local adaptation on the part of new human arrivals. In a recent study I was involved in, working closely with a prolific team at the University of Cologne who had undertaken decades of fieldwork in the Congo Basin, we were lucky enough to study Bantu-speaking populations moving into the far, forested reaches of the region. Here, the earliest arrival of pearl millet occurred as part of a diverse strategy that included heavy reliance on freshwater fish and the use of wild and domesticated forest plants. Similar “mosaic” strategies of food production continue to be sustainable in this part of the Congo Basin, showing that there is no necessary, single path to farming in tropical forests, even for incoming populations.19
THE DILIGENT WORK of archeobotanists (especially microbotanists), zooarcheologists, plant geneticists, and archeologists has demonstrated that tropical forests are crucial sites for scientists studying the earliest prehistoric farming practices on a global scale. It is in tropical forests that humans apparently first began to interfere with habitat structures, plant growth, and animal distributions. It is also in tropical forests that some of the earliest examples of farming practices occurred. Next time, before you put sugar in your coffee, before you peel a banana, before you apply moisturizer to your skin, or before you tuck into some sweet potato fries, remember just how many of our modern tastes and styles are fed by human activities in these environments that occurred throughout the Holocene. The “Fertile Crescent,” the dry highlands of Mexico, the rivers of North America, the great valleys of China, and the Saharan border of Africa have all proven key centers of domestication and agricultural origins, particularly in terms of animals and crops farmed in the way we think farming should happen from the view out of our Euro-American bubbles. However, tropical forests also witnessed some of the most significant and effective examples of food production as prehistoric societies harnessed the huge diversity of species these environments had to offer. This is particularly the case when we move away from the popular myth that tropical forests are solely characterized by dense, light- and soil-poor rainforests and look at the diversity of more seasonal forest environments that hosted some of the earliest examples of tropical food production discussed above. The changes to the landscape might not have been obvious to us, but they were certainly real.
In fact, considering the issues of land-use sustainability we face around the world in the twenty-first century, tropical forests give us a remarkable lens for viewing some of the most ecologically savvy of farmers there ever were. Locally domesticating plants and animals, early tropical farmers managed these forms of food production within forests that were by and large left standing and their wildlife left abundant, although their structure and species distributions may have been altered. Even some past farmers who moved into tropical forests with domesticated plants and animals from elsewhere, which often required more open, drier conditions, developed sustainable, mixed approaches that combined a wealth of local, wild tropical resources with these useful new species. These examples provide food for thought when we think of some of the disasters that governments, companies, and even our own choices wreak on these environments today in the name of “development,” “infrastructure,” or “productivity.” The past shows that tropical forests can be used and adapted, even within frameworks of farming, without being removed forever. However, some prehistoric societies certainly did remove the forests, literally clearing the way for types of “agriculture” that would have felt more familiar to us. This could have major consequences in the form of destabilized landscapes and soil erosion, collapses in biodiversity, and increased vulnerability to extreme weather events. This was particularly the case when new desires for “food production” washed up on the shores of more isolated, tropical islands.
Chapter 8
ISLAND PARADISES LOST?
We are used to seeing t
ropical islands, like the forests they are home to, as untouched “deserts” or blissful paradises. Whether you are a rum-sodden Jack Sparrow, an inventive Robinson Crusoe, a delivery man with a volleyball, or a troubled Jack Shephard trying to lead a ragtag group of “lost” lottery winners, conmen, artists, and rock stars, tropical islands represent an inescapable nightmare of being stranded in maddening isolation. Reality shows like Survivor often use tropical islands as the setting for testing the survival skills, social interactions, and morals of twenty-first-century societies. For many of us, they are the dream, but perhaps impractical, holiday: clean blue oceans, fine white sand, and quiet palm trees—places where we could finally “get away from it all.” For some sickeningly wealthy people who can afford to actually buy these landmasses, this is already a heavenly reality. Either way, it is probably a good thing that we widely view these tropical islands as arenas generally inaccessible to humans—especially as we tend to also stereotype them as being biologically and ecologically fragile. They are often small, so their soils and forests can change rapidly across much of the island surface in the face of external threats. While they are home to high levels of plant and animal biodiversity, unique species are often present in low numbers. Plants often have limited capacities to disperse their seeds widely. Meanwhile, isolated island animals frequently have few defenses against predators and competitors. Close bonds between species also mean that a cascade of extinctions can occur should one begin to dwindle. Together, this all means that island ecologies have been seen as particularly vulnerable to the invasion of new, competing species or predators, including Homo sapiens.1