Artificial intelligence (AI) has allowed computers to solve problems that were previously thought to be beyond their capabilities, from defeating the best human opponents in complex games1 to automating the identification of diseases2. There is therefore

Artificial intelligence (AI) has allowed computers to solve problems that were previously thought to be beyond their capabilities, from defeating the best human opponents in complex games1 to automating the identification of diseases2. There is therefore great interest in developing specialized circuits that can complete AI calculations faster and with lower energy consumption than can current devices. Writing in Nature, Chen et al.3 demonstrate an unconventional electrical circuit in silicon that can be evolved in situ to carry out basic machine-learning operations.