Medicine may be reducing the human capacity to survive.

It appears that limited natural selection is taking place in populations of developed countries, since most individuals survive and have the full opportunity to reproduce. This paper addresses contemporary natural selection in a developed country (Australia) using the biological state index. Although the general context of this paper focuses on Australia it can be expected that most other first-world and/or developed countries follow a similar pattern. The findings of this study, that 98% of individuals survive through their reproductive period and have the full opportunity to reproduce, support predictions that natural selection has limited influence on the evolution of first-world populations. It appears that first-world populations may not be naturally well adapted to their environment but use medical treatments/technology to increase their survival capacity and maintain fitness. This has two apparent consequences. First, the fitness of individuals will decrease, since less favorable genes can accumulate in the population, and secondly, disease processes will remain fit as they adapt to the selective pressures exerted by medicine. If medical treatment becomes ineffective, extensive mortality is expected since fit disease processes will be unleashed on unfit human populations. It appears that a possible answer to these problems may be found in gene therapy. Copyright 2001 Harcourt Publishers Ltd.