Gene editing is already revolutionising research in the laboratory

In the late 2010s eight macaque monkeys were born at a laboratory in Shanghai. At first they seemed much like the other infants in the colony, but differences soon became obvious. They were much more active at night than their peers. Their hormones were unusual, too. Melatonin, which typically oscillates with the day-night cycle and aids sleep, was all over the place. Cortisol, a stress hormone, was perpetually high. Then their behaviour took a turn: they sat frozen in corners for long periods of time, fled in fear from their caretakers, and began burying their little heads in their hands—all signs of mental illness.