If anyone did create an edited baby, it would raise moral and ethical issues, among the profoundest of which, [Jennifer Doudna] had told me, was that doing so would be “changing human evolution.” Any gene alterations made to an embryo that successfully developed into a baby would get passed on to any children of its own, via what’s known as the germline. What kind of scientist would be bold enough to try that?
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Editing human embryos is restricted in much of the world—and making an edited baby is flatly illegal in most countries surveyed by legal scholars. But advancing technology could render the embryo issue moot. New ways of adding CRISPR to the bodies of people already born—children and adults—could let them easily receive changes as well. Indeed, if you are curious what the human genome could look like in 125 years, it’s possible that many people will be the beneficiaries of multiple rare, but useful, gene mutations currently found in only small segments of the population. These could protect us against common diseases and infections, but eventually they could also yield frank improvements in other traits, such as height, metabolism, or even cognition. These changes would not be passed on genetically to people’s offspring, but if they were widely distributed, they too would become a form of human-directed self-evolution—easily as big a deal as the emergence of computer intelligence or the engineering of the physical world around us.
