ABSTRACT
Perhaps two of the greatest human achievements to have occurred from prehistoric to more recent times, and, particularly, in the last two centuries, are the increase in the human population worldwide and the extension of human longevity. Thanks to improved living conditions stemming from advances in agricultural practices and advances in industry and technology, the human population today has reached an unprecedented size (1-3). Living conditions have greatly improved due to
1. public health reforms and improved personal hygiene, 2. advances in medical knowledge and practices, 3. vastly increased control over the environment, and 4. rising income and standards of living.
