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Early hunter gathering

Survival by hunting, whether by humans or wolves, means the group needs to be compact and mobile to rapidly follow the food source. The population must also be small and kept that way, either by restricted breeding or infanticide. My instinct would be to suppose that small populations do not greatly modify their environment. This is false: very recent evidence has emerged that the reintroduction of a few dozen wolves into Yellowstone National Park has not only changed the balance of animals living there, but also had a major effect on the vegetation, and an increase in the number of trees that managed to grow past the sapling stage before being browsed. This in turn has changed the run-off and water movements and the stability of the rivers. For most of us, this is a totally surprising result, and only a very knowledgeable and enthusiastic ecologist would have considered such major and positive changes arising from a few predators. The effectiveness of the wolves is of course emphasized by the character of the national park, but the implication that a minor change in the balance for survival of some species has wide-ranging impact on the environment is remarkable. To put this in perspective, Yellowstone National Park is roughly the size of Northern Ireland or Corsica. So for most of us, we would assume a few wolf packs in such a large area would have only very local impact.

Enforcing the maximum pack size is fine for wolves, but for humans there is a very long time needed to reach maturity, so there are advantages in staying in a more settled pattern, and that means there are benefits from an element of agriculture. Early versions may have been to clear small areas of land, grow crops for a season or so, and then move on. With simple tools this was literally only scratching the surface, so basically there was little permanent damage to the soils, and once the group moved along, the land, and even forests, could recover. Better technology, in the form of deeper-cutting ploughs, axes, and saws, started to make permanent changes. The ploughs destroyed root systems and unbalanced the soil composition to greater depth, and of course cutting down the larger trees would make permanent changes to the entire local environment, from plants to animals. Looking at the scale of current forest destruction with modern massive machinery, it is immediately apparent that even the pristine jungles, of, say, South America or the Pacific, are not just being cleared, but totally destroyed forever. The species of plants and animals that have gone will never recover, even if humans self-destruct and leave the land to re-establish itself. In the long term, this is inevitable, but the selfish immediate concern is to allow humans to survive for a few more centuries.

In order to be an effective animal, we are very self-centred. Religions and traditions may claim there are seven deadly sins (lust, gluttony, greed, sloth, wrath, envy, and pride) that are, by religious definition, undesirable characteristics. In excess, I agree, but basically they are the very same motivating forces that have moved us from animals to a moderately intelligent species with great inventive capacity. A rapidly expanding population growth, ongoing warfare, extreme nationalism, acceptance of ideas from leaders rather than thinking for ourselves, obesity, and a desire for luxuries and non-essentials, etc. can all be linked to one or more of the list of seven. But without these characteristics, we would have remained a minor, weak species.

Indeed, all these factors are central to how we have developed agriculture, and also why we so often fail to see the damage that we are doing with our ‘improved’ methods. For management and simplicity, there are obvious benefits of having large fields producing the crops that we want, or grazing the type of cattle that seem most useful. Because of this, we have removed or destroyed animals that originally existed, and replaced them with our crops and livestock. A classic recent historical example is that within a 50-year period in America, we wiped out around 50 million bison. This conscious destructive act was so that we could grow crops or have ranches for cattle that we introduced there. At the same time, we destroyed or marginalized the indigenous human population and their food source. This may be classic Seven Deadly Sins’ behaviour, especially since we overlooked that the overall health of the land has evolved over a far longer period that have humans. Not only are there many creatures that will eat our crops (hence by definition we view them as pests—including the bison), but also they are a food source for other creatures.

Most obviously in the case of the small creatures that eat grain, we cause new problems, as once we destroy the established balance, we discover that some other new pest takes over because there are no longer any natural predators to limit their population. Other factors that we tend to ignore are where we have indirect, but essential, benefits from the so-called pests. Attempts to reduce insect populations are chemically feasible, but in so doing we lose bees and other insects that are crucial for fertilization and pollination. My description is very simplistic, as in reality we also need to consider all the bacteria in the soil, the worms, etc. and their far more complex stabilizing activities in maintaining fertile and continuously productive land that we can farm. Once we destroy this balance, and also extract key minerals that are catalyzing growth, then the ground will become barren and less productive. Eventually it will crumble and turn into a dust bowl or arid desert. A further dilemma is that for crop growth, it is essential to have a steady supply of water, and ways to retain moisture in the soils, as without water, even the best of soils will produce nothing.

Early, very small-scale, local farms, which were self-sufficient, avoided many of these difficulties. Animals were reared, ground was watered, food was eaten, and the waste products finished up as fertilizer that went back to the soil. In many cases, the farmers realized that they could not continuously take a single crop from the same area, so there were attempts at crop rotation or leaving the ground fallow for a season or so to let it recover. The farms were still liable to fail if rainfall changed, so there was generally a move to add irrigation from other water sources. Less obvious is that when we add water for irrigation, it evaporates and leaves residues such as salt. In particular, salt steadily undermines productivity, as it interferes with the chemistry that fixes nitrogen from the atmosphere into the useful biochemistry of soil. Many such historical examples exist—even the Fertile Crescent of Mesopotamia suffered in this way. The changes were slow, and productivity halved over a millennium, so the pattern was probably not obvious within a single generation. Salt problems were of course understood, and used deliberately by the Romans to contaminate the fields of their enemies in Carthage on the North African coast.

Climatic fluctuations, whether long-term or just for a few years, have always had a major impact on survival, and these are not within our control. The Inca civilizations on the west coast of South America oscillated between weather conditions of rain and plenty, and drought and nothing, as the El Nino current in the Pacific came and went. The Incas survived by having exceedingly well-designed storage systems that could distribute food across their nation. Indeed, it was this organization that bound them together, rather than military power. Similarly, some 5,000 years ago, Northern Africa lost its annual monsoon rains and went from being fertile savannah to a desert. The climate shift in this case has sometimes been linked to a minor tilt change of the rotation axis of the earth. A small and inevitable process such as this is sufficient to be locally catastrophic. The effect of the African climate change was visible in human terms by the growth of the Egyptian Empire. Their success and long-term stability is attributable to well-organized food storage to carry them through periods of poor crop yields, plus annual floods from the Nile to fertilize the soil. The biblical writings claim Egypt had periods of seven good years and seven poor ones, so their organizational skills must have been remarkably good.

Not all ancient civilizations were equally successful: the Aztecs were effectively destroyed by a prolonged drought even though they had storage tanks that would take them through their normal half-yearly dry seasons. But these were inadequate for a much longer drought. Many other examples of collapse can be cited from across the globe where changing climate patterns, droughts, or floods hit major civilizations from the Americas to Cambodia or China.

These are dramatic events for the civilizations that survive or collapse, and the changes are driven by natural climatic fluctuations that have shifted the regions that are habitable and fertile from one zone to another. It is essential to realize that our current input to climate changes from atmospheric pollution and the consequent upward drift in temperatures is not of the same character. We are not merely shifting areas that are agriculturally preferable, but instead are introducing a global temperature rise, and this can have a whole new gamut of changes that differ from the natural events. Far back in the history of the planet, the average temperature was very much higher than now, but it could not have sustained the flora and fauna (including us) that we now see and use for survival.

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