1.1: Reading/Media

Perspective - Geodiversity Breeds Cultural Diversity

By Likwan Cheng

Holocene climate change—the long, winding period of warming following the Last Glacial Maximum some 12,000 years before the present (BP)—coincided in time with the transition of human society from foragers to farmers and then to urban settlers. As this climatic shift swept across the globe, it transformed geological landscapes in every corner of Earth, driving human adaptations in various ways. It was in this precarious environment and through such geological forces that the world's earliest cultures took shape.

In the Nile river valley of North Africa, a previous high-water swamp too wet for habitation gradually gave way to a harsh, equally inhospitable arid desert. Between these two extremes, a period of climate moderation once emerged. Seizing the moment, human settlers migrated toward the Nile valley. With fertile soils on the floodplains and efficient river transportation, the early Egyptians built a thriving civilization around 5,000 BP. On boat travel on the Nile, they admired the elegant hills lining the horizon and were inspired to build spiritual monuments emulating their geometry and scale. Millenniums later, the Egyptian pyramids stood above a transformed landscape as a testament to the early civilization while continued aridification had swept away the settlements below and buried the river branch that had once transported the building stones in sand.

Figure \(\PageIndex{1}\): Decorated jar with boat scene, ca. 3,300-3,100 BCE. Clay pottery. The decoration painted on this jar shows two multioared boats traveling through riverbanks lined with trees and aloe bushes. Rows of hills line along the river bank. The Nile river was ancient Egypt's primary means of transportation. (Cleveland Museum of Art.)

On the Yangtze river delta in East Asia, the Holocene climate shift drove a monumental transformation of a different kind. Faced with a watery landscape created by fluvial floods from the melting of upstream glaciers, early humans turned challenge into opportunity. With fire and flood management, they cleared out coastal swamps to construct the first paddy fields for rice cultivation as early as 7,700 BP. Once wandering foragers who hunted animals and gathered wild rice in the lower Yangtze basin, they were now on a trajectory to become farmers through the domestication of rice, and with further hydraulic advances by 5,100 BP, urban settlers of a complex society. But the early Chinese proved to fare no better than the early Egyptians. As the Holocene warming continued, the rising sea inundated their farms and collapsed the nascent civilization. History would ultimately vindicate these early pioneers, as the rice farming they championed would become the subsistence foundation of the forthcoming agricultural Chinese society, lasting for five millenniums.

Figure \(\PageIndex{2}\): Rice farming in ancient China. Continuous narrative painting depicting scenes of farmers planting seedlings in rice fields. Qing dynasty (1644-1911 CE). (National Palace Museum, Taipei.)

In Mesopotamia, today's Middle East, the Holocene climate change led to far-reaching development in yet another dimension. As the pluvial phase of the early Holocene gave way to the progressively drying periods of middle Holocene, the region's two famed rivers, Tigris and Euphrates, changed course, exposing fine river-laid clays on the alluvial plain between them. Aridification transformed natural, rain-fed agriculture to managed irrigation and accelerated the transition to an urban society. The demand for administrative and economic recordkeeping led to the innovation of pictographic notations scripted on tablets of the river clays. Soon, these notations evolved into the world's first written language. When baked, the tablets became as resistant to weathering as rock, carrying their messages millenniums into the future. "Through them," the twentieth-century archaeologist Edward Chiera wrote, "we can follow changes in religious beliefs, economic conditions, and customs in daily life. In fact, through them we can...resurrect the old civilizations in the minutest details." (Chiera, 1938)

Figure \(\PageIndex{3}\): A cuneiform clay tablet from ancient Mesopotamia. (Institute for the Study of Ancient Cultures, University of Chicago.)

These historical episodes are among the eight episodes of ancient geology and cultural development with water-related themes to be explored in this book. Spanning five millenniums and crossing five continents, these episodes include crucial discoveries made in the first quarter of the twenty-first century. Read alone, each episode showcases how geology shaped human cultural development in a monumental way, as exemplified above in spiritual monuments, subsistence agriculture, and written language. Read comparatively, the episodes further reveal how nuanced variations in geological contexts triggered corresponding variations in cultural responses. For example, the Amazonian culture developed drainage networks on forest savannas to cultivate maize, while the Chinese culture developed hydraulic systems on the Yangtze delta to cultivate rice. Similarly, the Maya used volcanic silicates to filter water to keep it clean over time, while the Romans used volcanic ash to build aqueducts to transmit water over distance. Geological variations were tied to variations in human cultural development. In both monumental and nuanced ways, Earth's geodiversity shaped the world's human cultural diversity.

Geodivervity to the physical world is the conceptual equivalent of biodiversity to the living world. Having first emerged in the academic literature in the 1990s, the term geodiversity in the conventional view refers to Earth's geological variations, including materials (minerals and rocks), geomorphology (landforms and topography), and geological processes (climates and climate change). Geodiversity and biodiversity together make up the diversity of nature. Now, at the beginning of the second quarter of the twenty-first century, scholars are seeking a more expansive and integrative view of geodiversity, one that connects to Earth's other spheres. Among these is the connection to humans and human cultures. Scholars have pointed out that "geodiversity shaped the history and development of human societies since their earliest days" and that, conversely, "the role of current and past human activities in shaping geofeatures has been documented for centuries." (Scammacca and Bétard, 2026) To the human society, geological scarcity mirrors ecological fragility. Just as cultural diversity helps maintain Earth's biodiversity (Cheng, 2012), it also helps maintain Earth's geodiversity.

The entangled histories of Earth's geological transformation and human cultural development are fascinating and educational. But this vast record of past millenniums is not yet fully accessible. Buried below thick sedimentation and hidden by dense vegetation, human-modified landscapes and embedded cultural artefacts that attest to the stories of the past are not readily in view. But twenty-first century technologies are changing this. At the landscape scale, new aerial sensing technologies, such as LIDAR, or light detection and ranging technology, can map large areas of Earth's surface in infrared light and digitally remove covering materials to unveil the hidden topography below. At the microscopic scale, refined instrumentations, such as advanced X-ray imaging, now allow scientists to probe minerals and rocks in tiny grains with atomic-scale resolution and chemical sensitivity. These new technologies are joining traditional excavation to make new discoveries.

What these discoveries transpire are ancient stories presented in a new light or told for the first time, often leading to revised or newly established views. The indigenous settlement in Amazonia discovered under forest canopy that was once thought nonexistent and the self-healing ancient Roman concrete created through natural mineral-water reactions that outlasts modern steel-reinforced concrete by millenniums in longevity are revelations of past and present biases due for correction or improvement. How the stories are presented also matters. The twentieth-century historian Arnold J. Toynbee argued that human stories of the past may be presented in three ways—as history, science, or fiction—and the choice is to be judged on the ground of the quantity and quality of data at hand (Toynbee, 1957). The educational endeavor through a limited number of episodes demands an objective presentation of facts (history) rather than a forum for speculation (fiction) or generalization (science). And objective storytelling is best done through the words of the scholars who made the discoveries, as excerpts from original scholarly texts. With this approach, we will undertake our exploration.