A year later, his provocation had become reality. In May 2016, scientists, lawyers and government representatives converged at Harvard to discuss the Human Genome Project-Write (HGP-Write), a plan to build whole genomes out of chemically synthesised DNA. It will build on the $3 billion (£2.3bn) Human Genome Project, which mapped each letter in the human genome.
Leading the Harvard event was Church, whose lab is synthesising the 4.5-million-base-pair E. coli genome, and Jef Boeke 1, the NYU School of Medicine geneticist behind the yeast synthesis project. "I think we realised the two of us were getting good enough at those two genomes that we should be discussing larger ones," says Church.
A Science paper published after the meeting formally laid out the group's proposal: to dramatically advance DNA-synthesis technologies so that the artificial production of genomes becomes easier, faster, and cheaper. Currently, we can synthesise short strands of DNA, up to about 200 base pairs long, but the average gene has several thousand base pairs. Even this limited process is inefficient, costly and slow. But it's vital: in biological sciences, synthesised DNA is the foundation of experiments that drive everything from cancer research to vaccine development. For scientists, it's like working with a blunt yet necessary instrument.
The immense three-billion-base-pair human genome is seen as the project's ultimate goal, dangling like a carrot to drive innovation. Scientists intend to have fully synthesised it in a living cell - which would make the material functional - within ten years, at a projected cost of $1 billion. The fruits of HGP-Write could have wide-ranging, real-world impacts. But in its current form, say the scientists, it's primarily a call for technological advancement in synthetic biology. The May announcement received a frosty reception from some, however. A handful of scientists invited to the event declined to attend, due to organisers' decision not to include the press. Church says they were excluded because of an embargo on the forthcoming paper.
There are bigger concerns: artificial production of genomes raises the ethically unsettling question of gene patenting. Other worries, echoing those that first surrounded the gene-editing technology CRISPR, are of designer humans and parentless babies. "Moving beyond reading DNA to writing DNA is a natural next step," concedes Francis Collins, director of the US National Institutes of Health. He warns, however, that any project with real-world implications would require "extensive discussion from different perspectives, most especially including the general public".
Applications beyond the lab are a distant reality: synthesising a human genome may even prove unworkable. In any case, none of the project's deliverables will be "as exciting or as evocative as a baby", Hessel says. "Some of the things that were said [after the meeting] were so ludicrous that it allowed us to get through that bubble of misinformation and misinterpretation quickly."