What 2,500 Sequenced Genomes Say about Humanity’s Future

When the geneticist Gonçalo Abecasis stood up in front of a group of scientists in 2007 and proposed sequencing 1,000 genomes from people all over the world, he had no idea how he was going to pull it off. The Human Genome Project had published the first complete map of the human genome just four years earlier, and the technology remained exorbitantly expensive. “Imagine you’ve done ten of these,” Abecasis says today of the number of human genomes that had been sequenced at the time. “The first one cost $3 billion, and the other ones cost several million. And you say, ‘what if we set out to do a thousand?’”

The price wasn’t the only hurdle. “When we first started talking about doing these genome-wide comparisons between populations”—i.e., groups of people from different continents or with different ancestries—“there was a lot of tension,” remembers Abecasis, now at the University of Michigan. That’s because, frankly, “human population” sounds a lot like “race.”

Sequencing the human genome showed that humans are all much more alike than different; genome pioneer J. Craig Venter...