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Human Culture and Soils
Daniel Hillel
Center for Climate Systems Research, Columbia University, New York, New York, U.S.A.
INTRODUCTION
Our species’ birthplace was evidently in the continent
of Africa, and the original habitat was probably the
subtropical savannas that constitute the transition
zone of sparsely wooded grasslands lying between the
zone of the humid and dense tropical forests and
the zone of the arid 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.
For at least 90% of its existence as a species, the
human animal functioned merely as one member of a
community of numerous species who shared the same
environment. Early humans were adapted to subsist
within the bounds defined by the natural ecosystem.
By and large, our ancestors led a nomadic life, roaming
in small bands, foraging wherever they could find food.
They were gatherers, scavengers, and opportunistic
hunters. Unlike their primate cousins who remained
primarily vegetarian, humans diversified their diet to
include the flesh of whichever animals they could find
or catch, as well as a variety of plant products such
as nuts, berries and other fruits, seeds, some succulent
leaves, bulbs, tubers, and fleshy roots.
EARLY DEVELOPMENT
Some hundreds of thousands of years ago, members of
the Homo genus learned to fashion stone tools as well
as to set and use fire, probably at first only to cook and
soften food. Later, they used fire to clear woody
vegetation, to flush out game, and to encourage the
subsequent grazing of ungulates, which they could
thereby hunt more readily. Eventually, that practice
had a great effect on the environment, as brush fires
apparently set by humans modified entire ecosystems
on an increasing scale. The control of fire became even
more important when humans moved out of the tropics into colder climes, where bonfires and hearths
were needed to warm their shelters in winter as well
as to cook their food. In time, the clearing of woodlands and shrub lands by repeated firings also set the
stage for the advent of agriculture. However, as the
vegetative cover is affected by fire, so is the underlying
Encyclopedia of Soil Science DOI: 10.1081/E-ESS-120006604
Copyright # 2006 by Taylor & Francis. All rights reserved.
Copyright © 2006 by Taylor & Francis
soil. Following repeated denudations of the land, soil
organic matter and nutrients were gradually depleted,
while soil erosion took place, resulting in the increased
transport of silt by streams and its deposition in river
valleys and estuaries.
By the later stages of the so-called Paleolithic period, nearly all the regions of human habitation had
experienced some anthropogenic modification of the
floral and faunal communities. The gradual increase
in human population density required the development
of more intensive methods of land use, aimed at inducing an area to yield a greater supply of human needs.
The selective eradication of less desirable plant and
animal species and the encouragement of desirable
ones (producing edible and, preferably, storable products) led eventually to the domestication and propagation of crops, and to purposeful soil management
aimed at creating favorable conditions for production.
That is to say that these activities culminated in the
development of agriculture and the sedentary (rather
than nomadic) way of life in regular villages.
THE AGRICULTURAL TRANSFORMATION
Concurrently with the domestication of plants,
humans also learned to select and domesticate animals.
The earliest domesticates in the ancient Near East were
sheep, goats, and bovine cattle, which could be herded
and pastured in the semiarid rangelands. Cattle (oxen)
were also used as beasts of burden to pull carts and
plow the soil. Donkeys, horses, and eventually camels
were also harnessed in the same region to convey
people and goods.
The agricultural transformation, also called the
Neolithic Revolution, was very probably the most
momentous turn in the progress of humankind, and
many believe it to be the real beginning of civilization.
It first took place in the Near East approximately ten
millennia ago, initially in the relatively humid subregions where precipitation was sufficiently abundant
and regular to permit rainfed farming. Agriculture
was later extended to river valleys in the drier zones
by means of irrigation, which was based on the diversion of water from rivers onto adjacent flat lands.
At the same time, humans discovered that, by kneading
and shaping lumps of clayey soil and then baking them
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Human Culture and Soils
in ovens, they could fashion vessels for storing water as
well as for cooking food. Bricks made of molded clay
served for the construction of homes and grain
storages, while tablets of clay could be imprinted with
various signs to form permanent records in an early
form of writing called cuneiform. Later still, people
learned to extract, alloy, and mold metals such as
copper and iron and to fashion them into implements.
Rain-fed and=or irrigated farming practices, along
with ceramics and metallurgy, later spread to, or were
developed independently in, most of the other humaninhabited regions around the world.
The ability to raise crops and livestock, while resulting in a larger and more secure supply of food than was
possible previously, definitely required attachment to
controllable sections of land and hence brought about
the growth of permanent settlements and of larger
coordinated communities. The economic and physical
security so gained accelerated the process of population growth and necessitated further expansion and
intensification of production.
been occurring on a vaster scale in the African Sahel
which is the continent-wide semiarid savanna belt that
lies between the Sahara desert in the north and the tropical forests in the south. A particularly disastrous
example of waterlogging and salination because of irrigation is seen in the Aral Sea Basin of Central Asia
(Uzbekistan, Turkmenistan, and Kazakhstan). The
same processes are occurring in highly developed parts
of the world, such as the Murray-Darling Basin of
Australia or San Joaquin Valley of California. Even
more consequential is the large-scale destruction of
rainforests and the loss of biodiversity resulting from
the expansion of agriculture in the tropical zones of
South America, Central Africa, and Southeast Asia,
where the warm temperatures and high humidity contribute to the rapid decomposition of the soil’s original
organic matter content and to the deterioration of the
soil’s structure as well as its nutrient content.
LAND DEGRADATION
In addition to its uses for agricultural production, the
soil also serves human communities as a depository of
waste products—domestic, agricultural, and industrial.
In principle, the soil is endowed with inherent capacities to absorb, retain, and decompose many waste
materials and pathogenic agents that might otherwise
accumulate to poison the environment. However, those
capacities are limited, and when exceeded by the application of larger than normal quantities of potentially
toxic wastes (such as pesticides, heavy metals, hydrocarbons, and nonbiodegradable synthetic compounds),
the soil may merely be a way station, detaining but not
retaining harmful agents, which it eventually releases
to the biosphere.
Prospects for improving the management of soils in
the future will likely be affected by the threat of global
warming, because of the increasing concentrations of
radiatively active gases in the atmosphere. In a warmer
world, all weather phenomena may be intensified, with
more frequent and stronger rainstorms punctuating
longer and more severe droughts. Such a trend will
require far-reaching and expensive adjustments in the
zonation and methodology of agricultural production
as well as in water storage and supply facilities.
The evolution of agriculture left a strong imprint on
the land in many regions. The vegetation, animal
populations, slopes, valleys, and soil cover of land
units were radically altered. The practices of tillage
and fallowing, terracing, and irrigation and drainage,
as well as grazing of flocks, further accelerated soil erosion in sloping lands and sedimentation in lowlands.
Soil lost from denuded cultivated slopes could not be
regenerated unless the land was allowed to revert to
its vegetative cover for many decades or centuries.
Moreover, soils that were irrigated in poorly drained
river valleys tended to become waterlogged and saline,
with the result that the practice of farming could not be
sustained there in the long run.
The same anthropogenic processes, which began in
the early history of civilization, have continued ever
since on a more extensive scale. Especially vulnerable
are cultivated and overgrazed soils in semiarid regions,
where droughts occur periodically, accompanied by
strong winds that deflate the bare and pulverized soil
surface, and where the intermittent onset of rains
causes further damage. Consequently, once-productive
lands may become so degraded as to acquire desert-like
characteristics. Hence, the process of land degradation
in semiarid regions has been termed ‘‘desertification.’’
Examples of large-scale land degradation can be
cited in many parts of the world. A case in point is
the famous ‘‘Dust Bowl’’ that took place in the
Southern Great Plains of the United States in the
1930s and that caused the uprooting and migration
of entire farming communities. A similar process has
Copyright © 2006 by Taylor & Francis
THE IMPERATIVE TO IMPROVE
SOIL MANAGEMENT
CONCLUSIONS
Humanity now depends on the soil more crucially than
ever, not only because population has grown but also
because available soil and water resources have diminished and deteriorated. Our needs and those of future
generations require us to seek better ways to manage
Human Culture and Soils
those precious resources judiciously and sustainably.
What past generations despoiled inadvertently owing
to lack of comprehensive scientific knowledge or
social-environmental consciousness, we must begin to
rectify deliberately. Developing, disseminating, and
applying knowledge of the soil and its processes are
essential tasks if we are to ensure the lasting welfare of
humanity as well as the terrestrial ecosystem as a whole.
Copyright © 2006 by Taylor & Francis
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BIBLIOGRAPHY
Boyden, S. Biohistory: The Interplay Between Human Society
and the Biosphere; Paris: UNESCO, 1992.
Goudie, H. The Human Impact on the Natural Environment;
Cambridge, MA: MIT Press, 1986.
Hillel, D. Out of the Earth: Civilization and the Life of the
Soil; Berkeley, CA: University of California Press, 1992.