1) All humans are descended from Noah, his sons and their wives after the biblical flood, but different skin colors and features have developed in different groups over time. 2) Skin color is determined by multiple genes, and if groups intermingled freely new combinations could emerge, but barriers like language after the Tower of Babel led groups to develop distinct characteristics as they migrated and adapted to new environments. 3) The dispersion at Babel broke up the original group, ensuring different genetic mixes in smaller isolated groups that developed into what are now called "races" as environmental pressures further modified their features to suit local conditions.