National Geographic : 2017 Apr
Beyond Human 59 embryos to try to fix the genetic defect that causes beta-thalassemia, a po- tentially fatal blood disorder. Their attempt failed, but moved them closer to finding a way to fix the defect. Meanwhile there is an international mora- torium on all therapies for making heritable changes in human genes until they are proved safe and effective. CRISPR is no exception. will such a halt last? No one I spoke to seemed to think so. Some pointed to the history of IVF as a precedent. It was first touted as a medical procedure for otherwise infertile couples. Soon its potential to eradicate devastating genetic diseases was clear. Families with mutations that caused Huntington’s or Tay-Sachs diseases used the technique to choose disease-free embryos for the mother to carry to term. Not only was the child-to-be spared much misery, but so were his or her potential offspring. Even if this was playing God in the nursery, it still seemed reasonable to many people. “For this sort of technology to be banned or not used,” notes Linda MacDonald Glenn, a bioethicist at California State University, Mon- terey Bay, “is to suggest that evolution has been benign. That it somehow has been a positive. Oh Lord, it has not been! When you think of the pain and suffering that has come from so many mistakes, it boggles the mind.” As IVF became more familiar, its accepted purpose spread from prevent- ing disease to include sex selection—most notably in Asia, where the desire for sons has been overwhelming, but also in Europe and America, where parents talk about the virtues of “family balancing.” Officially, that’s as far as the trend toward nonmedical uses has gone. But we are the species that never knows when to stop. “I have had more than one IVF specialist tell me that they can screen for other desirable traits, such as desired eye and hair color,” Glenn told me. “It is not advertised, just via word of mouth.” In other words, a green-eyed, blond child, if that’s your taste, could already be yours for the asking. CRISPR is a vastly more powerful technology than IVF, with a far greater risk of abuse, including the temptation to try to engineer some sort of ge- netically perfect race. One of its discoverers, Jennifer Doudna, a professor of chemistry and molecular biology at the University of California, Berkeley, recounted to an interviewer a dream she’d had in which Adolf Hitler came to learn the technique from her, wearing a pig’s face. She emailed me recently to say she still hoped the moratorium would last. It would, she wrote, “give our society time to research, understand, and discuss the consequences, both intended and unintended, of changing our own genome.” On the flip side, the potential benefits of applying CRISPR to humans are undeniable. Glenn hopes at least for “thoughtful discussions” first on how the technique will be used. “What becomes the new norm as we try to improve ourselves?” she asks. “Who sets the bar, and what does enhance- ment mean? You might enhance people to make them smarter, but does smarter equal better or happier? Should we be enhancing morality? And what does that mean?” Many other scientists don’t think everyone will wait to find out; as soon as CRISPR is shown to be safe, ethical questions will recede, just as they Arsenic tolerance Some Argentine populations have adapted to tolerate high levels of arsenic commonly found in the groundwater where they live. Fat metabolism Inuit populations have a genetic variant that allows them to digest the fatty foods of their regional diet, like whales and seals. Domestication Animal and plant domestication, prob- ably spreading hand in hand, led to per- manent settlements and later to cities and civilizations.