Population growth and mortality rates will be key determinants of the composition and size of demand for agricultural production, and also the technology under which it is supplied. Increased populations generate increased demand for agricultural products, which must be supplied through an expansion or intensification of agricultural production. Demographic change is the key determinant of population pressures on the land, and thus important determinants of the rate and nature of agricultural intensification, with major implications for both biodiversity and biotechnology.

We are living in times of rapid and radical changes in population size and distributions. Global population growth rates are declining swiftly— from a peak of 2.04% per annum in the late 1960s to 1.35% per annum by the late 1990s (Bruinsma, 2003). It is projected to fall even further, to 1.1% per annum by 2015. Although rates are dropping, the absolute numbers of people added to the world's population each year are still quite large, particularly in developing countries. South Asia, East Asia, and Sub-Saharan Africa are the three areas where annual incremental population increases have been the highest over the past two decades and, thus, where a rapid growth in the working-age population is now occurring. Continuing large annual increases are projected to occur in South Asia and East Asia up to 2015. For Sub-Saharan Africa, however, the pandemic of HIV AIDS has resulted in a major shift in population projections and annual incremental increases, due to its impact on mortality rates among working age populations. In most of eastern and southern Africa the prevalence of HIV is over 10%. For some countries, negative population growth rates are projected by 2010 as the mortality from HIV outstrips new births (Jayne, Villareal, and, Pingali, 2004). Overall, the absolute numbers of adults projected to be alive in countries of Sub-Saharan Africa with HIV prevalence rates over 10% is roughly similar to what it is today. According to the projections, between 2000 and 2025 there will be a slight increase in the number of men between 20 and 59 years of age, but no change in the number of women (Jayne, Villareal, and, Pingali, 2004). However, HIV will also likely affect the productivity of the labor force, due to increased incidences of illness and lower capacity to perform work among afflicted laborers, as well as the need to divert labor to child care, funerals, and tending the sick among the population in general.

The impact of demographic change on agricultural technology choice and ultimately on biotechnology and agricultural biodiversity depends on the supply of factors of production aside from labor, such as land, capital, and technology. The distribution of these factors and policies that affect their relative prices will determine the degree to which an expansion in agricultural output will be met through increases in the extensive or intensive margin of agricultural production. FAO projects, which approximately 80% of the required growth in crop production will come from, increase in the intensive margin (i.e., increases in yields per hectare per year) (Bruinsma, 2003). Arable land expansion as a source of growth (the extensive margin) will be important in some Sub-Saharan and Latin American countries, although much less so than in the past.

In the past, and with the green revolution in particular, the intensification of agriculture and yield increases were accomplished partially through the adoption of improved varieties, which has also been associated with changes in crop genetic diversity, although there is some controversy over whether the direction has been negative or positive (see Chapter 3 for a detailed discussion; also Brush, 1999). The impacts of intensification on increasing crop genetic erosion and vulnerability are a serious concern (FAO, 1998; Matson et al., 1997). However, much of the areas where agricultural intensification through the adoption of monocultural systems has not yet taken place are characterized by a high degree of agroecological heterogeneity and poorly functioning markets, resulting in a higher value to maintaining diversity in the farming system (see Chapter 5). Intensification in these areas may require higher reliance on agricultural biodiversity due to the barriers to adoption of monocultural agricultural production systems (see Chapter 19; also Matson et al., 1997).

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