National Geographic : 2017 Apr
58 national geograpHic • april 2017 At first glance this would seem improbable. The genetic basis of intel- ligence is very complex. Intelligence has multiple components, and even individual aspects—computational ability, spatial awareness, analytic reasoning, not to mention empathy—are clearly multigenetic, and all are influenced by environmental factors as well. Stephen Hsu, vice president for research at Michigan State University, who co-founded the Cognitive Genomics Lab at BGI (formerly Beijing Genomics Institute), estimated in a 2014 article that there are roughly 10,000 genetic variants likely to have an influence on intelligence. That may seem intimidating, but he sees the ability to handle that many variants as nearly here—“in the next 10 years,” he writes—and others don’t think you’d need to know all the genes involved to start selecting smarter embryos. “ The question isn’t how much we know or don’t know,” Church says. “It’s how much we need to know to make an impact. How much did we need to know about small- pox to make a vaccine?” If Church and Hsu are right, soon the only thing holding us back will be ourselves. Perhaps we don’t want to practice eugenics on our own natural genomes. Yet will we pause? If so, for how long? A new technology called CRISPR-Cas9 has emerged, developed in part in Church’s lab, that will test the limitations on human curiosity. First tried out in 2013, CRISPR is a pro- cedure to snip out a section of DNA sequence from a gene and put a different one in, quickly and accurately. What used to take researchers years now takes a fraction of the time. (See “DNA Revolution,” in the August 2016 issue of National Geographic.) No technology remotely as powerful has existed before for the manip- ulation of the human genome. Compare CRISPR and IVF. With IVF you select the embryo you want from the ones nature has provided, but what if none of the embryos in a given set is, for instance, unusually intelli- gent? Reproduction is a crapshoot. A story, likely apocryphal, illustrates the point: When the dancer Isadora Duncan suggested to the playwright George Bernard Shaw that they have a baby together so it would have her looks and his brains, he is said to have retorted: “But what if it had your brains and my looks?” CRISPR would eliminate that risk. If IVF is order- ing off a menu, CRISPR is cooking. In fact, with CRISPR, researchers can insert a new genetic trait directly into the egg or sperm, thus producing, say, not just a single child with Shaw’s intelligence and Duncan’s looks but an endless race of them. So far many experiments using CRISPR have been done on animals. Church’s lab was able to use the procedure to reengineer pig embryos to make their organs safer for transplant into humans. A colleague of Church’s, Kevin Esvelt at the MIT Media Lab, is working to alter the mouse genome so the animal can no longer host the bacterium that causes Lyme disease. A third researcher, Anthony James of the University of California, Irvine, has inserted genes in the Anopheles mosquito that prevent it from carrying the malaria parasite. Around the same time, however, researchers in China surprised everyone by announcing that they had used CRISPR in nonviable human Thrifty genes Some genes found in tropical islanders aid survival on limited food resources but could lead to obesity in a high-calorie environment. Thick hair East Asians evolved thick hair shafts 35,000 years ago, perhaps through sexual selection orasanaidin regulating heat. Digesting seaweed In Japan, where a coastal diet dominates, genes in human gut bacteria help the local popula- tion extract nutrition from seaweed.