World population prospects: the impact of ecological and genetic factors on human population growth in the 21st century

Abstract

James V. Neel, one of the leading human geneticists of the 21st Century, has long been concerned about the consequences of human overpopulation and the accompanying destruction of the earth's ecosystem. His point of view, summarized in this paper, is contrasted with some recent optimistic projections presented by demographers and population biologists who believe the population bomb has been defused by evidence of a decrease in worldwide fertility along with a significant increase in food production. The authors of this paper are not so optimistic and see a continuing need for concern rather than complacency based on ever increasing human wants and aspirations together with the minimal results of recent environmental summits. The case of HIV/AIDS is used to illustrate the evolutionary implications of the interaction between population dynamics and genetic change based on the concepts of population bottlenecks, genetic drift and founder effects. What becomes evident from this illustration is that epidemics by viral and other pathogens in the 21st Century can affect the size of human populations and thereby the course of the species' evolutionary makeup. The potential of evolutionary medicine and in particular molecular biology to improve our prediction capabilities and modulate some of the possible consequences is discussed.