212 Scarcity and SurfeitThe traditional end of the continuum emphasises adaptation to unpre-
dictable seasonal extremes, and the influence of the environment's non-lin-
ear qualities on subsistence and land use strategies. Lineage and clan struc-
tures mediated local resource distribution; raiding and intermarriage served
as mechanisms for wider redistribution and spread risk; surplus in the form
of livestock was reinvested in wives and kin networks.
But increasing population densities and the Nuer expansion into the
region's most problematic ecological niche indicate that by the middle of
the century demographic growth was pressing against the region's highly
elastic ecological parameters. The Dinka, as noted above, were also expand-
ing on the flood plain periphery. They continue to do so even now - per-
sonnel from non-governmental organisations based in Rumbek and Mundry
county rank herder-farmer conflict as the leading form of resource-based
competition.
The concept of population pressure cannot be divorced from consideration
of the efficiency with which productive systems supply a given population
with sufficient material means of subsistence. All populations are under
some degree of population pressure. An increase in population density does
not necessarily result in an increase in population pressure - if the increase
in population density is accompanied by a proportionate increase in per capi-
ta productivity. For example: population density is higher today in Holland
than it was in the 14th century, but population pressure is lower.
Herring3%laims "the stereotyped image" of a Lwo cattle complex has
been greatly exaggerated. He observes that cattle are an element of subsis-
tence strategies with important cultural and religious roles, but kept only
where they could be maintained. For some migrating communities this com-
ponent grew in importance but not until the 19th century. Except for the
exceptional attention cattle receive from the Dinka and Nuer, he claims, pas-
toralism was not an entrenched practice among the Lwo. The concomitant
observation highlights the Nuer expansion as the high point of pre-colonial
subsistence technology specialisation.
During the same period the trend of out-migration to the south gave way
to influences from the 'Arab' north flowing in. The penetration of the Nile
Basin beneath the confluence of the Bahr Ghazal and Zeraf Rivers circa 1820
marks the turning point. Considering the massive changes and developments
overtaking the southern region's inhabitants since that time, the technologi-
cal stasis prevailing up to the recent present is indeed remarkable.
Respondents across the board underscore the 'primitive' state of subsistence
production everywhere in southern Sudan. Development of basic infrastruc-
ture (such as roads, communications, potable water) is only slightly higher.
The conquering agents of the Ottoman Empire built garrisons along the river,
set up telegraph lines, and instituted taxation. Expansion of irrigation agricul-
ture spreading down the river from Egypt demanded labour; the occupying