Genetic variation on Y chromosomes is due to mutations accumulated as men have descended from Noah. Many of the Y chromosome common variants found today were produced by historical events causing large demographic changes when the world population was small. To gain understanding of how the ancient events described in Genesis following the Flood may have produced these common variants, a computer model was built. Output from this model suggests that this common variant pattern is the result of tragic demographic events, including the Babel dispersion and the Ice Age, resulting in population collapse and opportunistic male reproduction. High mutation rates in long-lived patriarchs may also have contributed to increasing common variants on Y chromosomes. The model most closely matches the common variant pattern when parameters are adjusted to reflect the historic record of Genesis. The population expands rapidly with few deaths until 560 men with their families disperse from Babel. The model further suggests that patriarch profiles of mutations might be found on the Y chromosomes of all men today.