In chromosomes, long gaps exist without any genes at all. In other locations, they are packed together like pearls on a necklace. No one knows why the human genome is so lumpy, or carries so many useless letters. Researchers aren't finding much variation in human genes despite the great diversity of people who populate our planet. Modern humans are thought to have spread from Africa to Europe and Asia about 100,000 years ago.
Humans have much the same genetic makeup as they did when they walked out of Africa.
There are variations, of course. These variations account for such things as an individual's risk for heart problems and Alzheimer's disease, resistance to the AIDS virus, and whether a person will be born with type 1 diabetes, multiple sclerosis, or any of a long list of other genetic maladies. Several speakers at the symposium mentioned a goal of putting together a catalog, or table, matching variations in human genes with the afflictions they underlie. Once such precise information becomes available, scientist would know what targets they must hit with drugs and other treatments. Getting down to the chips Much of the symposium was devoted to techniques for reading the book of life and applying that knowledge to cure diseases.