Sugar is actually quite healthy when consumed in moderate amounts and in its natural form. The main natural source of sugar is fruit. In prehistoric times, vegetables were the most abundant foods and fruits were scarce in comparison. However, vegetables carry little energy compared to fruits. Therefore, the pre-human primates who consumed the most calories were the ones best able to stave off starvation and pass on their genes. Since fruits were relatively rare, the primates who ate the most of them were best positioned to win the battle of evolution. Public Domain Image, source: Christopher S. Baird. For this reason, genetic mutations that caused some of our ancient ancestors to crave sugary foods, and to be able to convert the sugar to body fat for future use, ultimately caused them to flourish. Simply put, early primates evolved to crave fruits precisely because these foods are so healthy in the small amounts that were available to them. Because it is more difficult to retrieve a fruit from a high tree than to just eat whatever grass or leaves are sitting around, an intense, innate craving for sugar was needed to drive early primates towards this food. Source: wtamu.edu by Sir Christopher S Baird......