  The century that opened with rediscoveries of Gregor Mendel's studies on patterns of inheritance in peas closed with a research project in molecular biology heralded as the initial and necessary step for attaining a complete understanding of the hereditary nature of humankind. Both basic science and technological feat, the Human Genome Project (HGP) brought to biology a “big science” model previously confined to physics. Although originating and centered in the U.S., laboratories across the globe contributed to the mapping and sequencing of the haploid human genome's 22 autosomes and 2 sex chromosomes.