How did humanity read its own genome, and what did it find?

The Human Genome Project set out to determine the base pairs of human DNA and to identify, map and sequence all of its genes. It began in 1990, and the essentially complete genome was announced on 14 April 2003, two years earlier than planned. It cost about $2.7 billion, less than expected, to read roughly 3.1 billion base pairs.

It was also a race. In 1998 Craig Venter's company Celera Genomics launched a private effort meant to go faster and at a fraction of the cost. The public project released its data daily, while Celera would not permit free redistribution. In March 2000 Bill Clinton and Tony Blair urged that the sequence should have unencumbered access, and Celera's stock plummeted. Venter later acknowledged that his own DNA was in Celera's pool of samples.

The result was a mosaic: the finished genome represents no single person, and more than 70% of the public reference came from one anonymous donor in Buffalo, New York. That works because the vast majority of the human genome is the same in all humans. The sequence also gave a gene count: about 22,300 protein-coding genes at first, later revised to roughly 19,000 to 20,000, the same range as in other mammals.