The talk was the first in a series sponsored by the Harvard Health Caucus, a student group based at HMS that sponsors discussion of health policy issues.

Collins emphasized that all humans have 99.9 percent of their genetic codes in common and there is very little variation between human groups from different locations.

"Most of those variations existed when we were all black Africans," he said. "There is no scientific basis for using ethnic or racial categories."

In addition to the discoveries about the differences between humans, Collins said the genome would allow doctors to predict and diagnose disease, as well as develop new drugs more quickly.

"The motivation for this is medical," he said. "We want to understand the hereditary sources of virtually every disease."

Collins said "pharmacogenomics," or the study of how medicines can be tailored to specific people, is already showing promise.

"The idea that we would want the genotype before writing the prescription is not far off," he said.