OUT OF THE EARTH
CIVILIZATION AND THE LIFE OF THE SOIL
UNIVERSITY OF CALIFORNIA PRESS 1991
PART II: THE NATURE OF SOIL AND WATER
Chapter 3: The fertile Substrate
Chapter 4: The Vital Fluid
Chapter 5: The Dynamic Cycle
Chapter 6: The Primary Producers
Chapter 7: The Tenuous Balance
PART III: THE LESSONS OF THE PAST
Chapter 8: Human Origins
History does not merely resurrect a dead past. In the words of Thucydides: “Knowledge of the past is an aid to interpretation of the future.” If we can truly learn from past experience, we may be better able to improve our current use of the environment. If we focus our attention exclusively upon the predicaments of the moment, however, we may find ourselves repeatedly surprised by a host of bewildering problems seeming to come out of nowhere, without a past and hence without direction. How did these problems arise? Chances are, the seeds of the phenomena we witness today were planted some time ago by our predecessors, as indeed we are planting the seeds of the future – perhaps unknowingly – at this very moment.
- The story of mankind begins more than three million years ago, when a genus of primates evolved to the point where it became recognizably humanoid.
- Over extended periods of time, biological evolution appears to proceed very slowly by a long series of small, almost imperceptible, changes.
- Then, periodically, thresholds are reached that trigger seemingly sudden transformations, due to chance occurrences of genetic mutations, or to shifts in environmental conditions, or – more likely – to combinations or sequences of these.
- Ever since Charles Darwin first elaborated on the possible circumstances of human origin in his 1871 book, The Descent of Man, anthropologists have been speculating on the sequence of events that gradually brought about the astonishing metamorphosis of a tree-dwelling, quadripedal, herbivorous ape into a ground-dwelling, bipedal, tool-making, omnivorous hominid.
- A crucial step appears to have been the shift from four-legged to two-legged locomotion.
- This was followed by further structural and functional evolution. The eyes were adapted to stereoscopic vision for judging distances.
- The hands developed a capability for the precision grip used in making and employing tools.
- The brain grew in size and function as it developed the ability to process more information and to generate complex logical thoughts.
Our species’ birth place was apparently in the continent of Africa, and its original habitat was probably the subtropical savannas which constitute the transitional areas of sparsely wooded grasslands lying between the zone of the humid and dense tropical forests and the zone of the semiarid steppes. We can infer the warm climate of our place of origin from the fact that we are naturally so scantily clad, or furless; and we can infer the open landscape from the way we are conditioned to walk, run, and gaze over long distances.
- Fossil discoveries in East Africa during recent decades have revealed facts that have added dramatically to our knowledge of human origins.
- For at least 90% of its career, the human animal existed merely as one member of a community of numerous species who shared the same environment.
- Humans neither dominated other species nor brought about any fundamental modification of the common environment. They were gatherers, scavengers, and hunters.
- They diversified their diet to include the flesh of animals as well as nuts, berries, fruits, seeds, succulent leaves, bulbs, tubers, and fleshy roots.
The story of how humans ascended from their humble apelike origins to venture far from their birthplace, and range over a variety of climates and landscapes, is a remarkable saga of audacity, ingenuity, perseverance, and adaptability. In fact humans have proved to be the most adaptable of all terrestrial mammals. Their mode of adaptation was not entirely genetic or physical: there was not enough time for that. Rather, their adaptation was in large part behavioural. Instead of relying on physical prowess, they had to use inventiveness to survive the elements and to compete successfully against stronger animals. In the course of their migration and expansion, our ancient forebears therefore had to develop and mobilize all the cunning and intelligence that eventually made them – and us – so unique a species. The increase of brain size and manual dexterity, as well as the invention of various stratagems, gradually enabled humans to overcome the constraints of their ancestry.
- By 1 million years ago, hominids had become taller (about 1.5 meters in height), and had acquired a larger brain.
- Some evidence has been found in Southern and Eastern Africa of repetitive occurrences of brush fires, apparently set by humans nearly a million years ago, signifying the beginning of human manipulation of the earth’s ecosystems.
- The use of fire became even more important when humans moved out of the tropics into colder climes.
- By about 250,000 B.P. (Before the Present), humans had evolved into the type that anthropologists call Homo sapiens, and had spread to Europe and Asia.
- Some time before 50,000 B.P., a race of humans called Neanderthals, who lived during the last Ice Age, were making cutting tools with flaked flint.
- By about 40,000 years ago, modern humans (Homo sapiens sapiens), evidently indistinguishable from us today in physical features and in intelligence, had gained dominance.
- Clad in garments made of animal skins, able to make and use a variety of implements, and armed with a growing array of weapons – including spears and bows and arrows – humans were able to range and settle in locations and climes far from their ancestral home.
All the while they continued to evolve biologically through genetic change and natural selection, increasingly aided by cultural and technological development. To survive the harsh winters of colder climates, they had to find or construct shelters, and to huddle in family or tribal groupings for mutual assistance and the rearing of their slow-growing offspring. In their leisure time, they painted animals on cave walls and carved ritual objects. They also had to contrive increasingly sophisticated methods of obtaining and storing foods, including the selective gathering, processing, and preservation of biological products, and eventually the domestication of plants and animals.
- This series of changes has been termed the Paleolithic (Early Stone Age) Transformation.
- Gradually, as they continued to elaborate and perfect their tools of wood, bone, and stone, as well as their techniques and social organization, humans assumed an increasingly active and eventually dominant role in shaping their environment.
- Each modification of the environment entailed additional human responses, which in turn further modified the environment, so that a process of escalating dual metamorphosis was instigated.
- Human intelligence and culture were both cause and effect in that fateful interplay. The peculiarly dynamic and progressive evolution of human ecology is the true history of our species.
- In time, the practice of clearing woodlands and shrublands by repeated firings also set the stage for the advent of agriculture.
- As vegetation is affected by fire-setting hunters, so are soils. Following repeated fires and deforestation, soil erosion and landslides often result in the greatly increased transport of silt by streams, and in the deposit of that silt in river valleys and estuaries.
- The gradual intensification of land use continued throughout the Paleolithic period, so that by its later stages nearly all the regions of human habitation had experienced some anthropogenic modification of the floral and faunal communities.
Humans recognized nutritional and medicinal plants, observed their life cycles, and learned to encourage and take advantage of their natural propagation patterns. They learned to build rafts and boats of various type and thereby to exploit aquatic resources. As they became more mobile, the rivers and lakes that were once barriers became arteries of travel and transport. They developed implements for grinding and cooking vegetable and animal products, and weapons for hunting larger game animals. Success in these endeavors provided them with the leisure to develop social and cultural activities: music, dances, rituals, ceremonies, storytelling, rites of passage, creative arts, and the crafting of useful and decorative articles. Their success also brought about a growth in population, which in turn induced further geographic expansion and intensification of land use in quest of additional sources of livelihood.
Chapter 9: The Agricultural Transformation