Reproducing laterĪn interesting consequence of improved medical technology is that humans can now reproduce, or prefer to reproduce, at a later age. This, rather than increased adult survival, is one of the major causes behind the increase in average life expectancy, and is linked to improvements in medicine and hygiene. This means that nearly all children in those countries will survive childhood and live to the age that they can reproduce. The last century has seen a tripling of newborn life expectancy in developed nations. In the developed world, over-use of antibiotics has led to most of the harmful bacteria becoming immune, so that many infectious diseases are once again becoming significant killers. Unfortunately, not all humans share such access to modern medicine and preventable infectious disease remains the largest killer of people in developing nations, accounting for over 40 per cent of all deaths. The application of vaccinations and antibiotics has reduced this figure to about 1 per cent. Infectious diseases are one of the major causes of human mortality and were responsible for over 25 per cent of all deaths in developed nations prior to the introduction of antibiotics in the 1940s. In the future, there will be a greater reliance on medicine for survival rather than genetic adaptations.
The major consequence of medicine has been the increase of genes that have little or no resistance to disease. However, due to the size of our population, this has little effect on the overall genetic make-up of our species. The benefits to the individual person are obvious. Today, medical advances have allowed those that would not previously have survived to reproduce and contribute to the human gene pool. In the past, those of our ancestors who were best adapted to the environment passed on their genes to their offspring.
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