Gene editing can make us different, but not better
The genetic change, even if it worked as advertised, would not be a clear-cut improvement but a trade-off
For such flawed creatures, human beings are surprisingly hard to improve, at least through our genes. That’s one reason there’s so much outcry over the recent claim that researchers in China altered the genes of a pair of twins girls — endowing at least one with resistance to HIV. The genetic change, even if it worked as advertised, would not be a clear-cut improvement but a trade-off.
Researchers disabled a gene called CCR5, which in its intact form helps HIV enter cells. Preliminary reports suggest the researchers succeeded in changing only one of the two copies of the gene in the other twin, which is not enough for HIV resistance.
Did the twin with the alteration receive a better version of the gene than she would have otherwise been born with? No, said Hank Greely, director of the Centre for Law and the Biosciences at Stanford University. “CCR5 is found in just about all mammals.”It’s probably doing something useful. We don’t know all the risks of disabling it, but in his view, the benefits are “small to nonexistent.” The benefit of the modified gene would vanish along with HIV, but its downsides would remain.
Maybe the perfection misconception stems from the ease with which scientists can improve plants and animals through genetic engineering. How could this kind of “improvement” apply to humans unless someone is thinking of us as a commodity? Only in dystopian stories does anyone use genetic modification to make people in some way better able to serve corporations or the state.
There are some legitimately bad genes, and scientists are working on so-called gene therapy to help people who’ve inherited them. But there are already safe ways for genetic diseases to be avoided, rather than edited. If people want to have children biologically and know they carry a mutation that puts their offspring at risk for a serious genetic disease, they can opt for something called pre-implantation diagnosis. This is genetic testing of embryos produced to ensure only ones without the deleterious mutation are implanted.
There are rare cases where genes can be both common and seemingly undesirable. One of these is a gene called ApoE4. Scientists studying a South American hunter-gatherer group called the Tsimane found that people with ApoE4 had a lower risk of Alzheimer’s – the opposite of the effect on typical subjects – but only if they also had certain parasites. Because most Tsimane people had parasites, ApoE4 was beneficial. This opens up the possibility that in the future, scientists will have figured out how to simulate the effect of parasites, and people with one or two copies of ApoE4 will be at less risk than the rest of us.
Life on earth has been evolving for 3.8 billion years and yet our planet has yet to produce a perfect species. That won’t stop people from trying. It seems inevitable that someone will eventually try to sell people genetic tweaks to give their kids a higher IQ. Who knows? Such a thing might make some of us quicker, but probably not wiser.