Nowhere to hide

Helen of Troy may have had a "face that launch'd a thousand ships", according to Christopher Marlowe, but these days her visage could launch a lot more besides. She could open her bank account with it, authorise online payments, pass through airport security, or raise alarm bells as a potential troublemaker when entering a city (Troy perhaps?). This is because facial recognition technology has evolved at breakneck speed, with consequences that could be benign or altogether more sinister, depending on your point of view. High-definition cameras combined with clever software capable of measuring the scores of "nodal points" on our faces - the distance between the eyes, the length and width of the nose, for example - are now being combined with machine learning that makes the most of ever-enlarging image databases. Applications of the tech are popping up all round the world. In China, for example, fried chicken franchise KFC recently unveiled its first "smart restaurant" that uses facial recognition to predict what meal customers are likely to want, based on their age, gender and the time of day, while payments giant Alipay is experimenting with "smile to pay" tech.