The brains of two genetically edited girls born in China last year may have been changed in ways that enhance cognition and memory, scientists say. The twins, called Lulu and Nana, reportedlyhad their genes modified before birth by a Chinese scientific team using the new editing tool CRISPR. The goal was to make the girls immune to infection by HIV, the virus that causes AIDS. Now, new research shows that the same alteration introduced into the girls’ DNA, deletion of a gene called CCR5, not only makes mice smarter but also improves human brain recovery after stroke, and could be linked to greater success in school. The Chinese team, led by He Jiankui of the Southern University of Science and Technologyin Shenzhen, claimed it used CRISPR to delete CCR5 from human embryos, some of which were later used to create pregnancies.HIV requires the CCR5 gene to enter human blood cells. The experiment has been widely condemned as irresponsible, and He is under investigation in China. News of the first gene-edited babies also inflamed speculation about whether CRISPR technology could one day be used to create super-intelligent humans, perhaps as part of a biotechnology race between the US and China.