Monkeys in modern-day Thai forests create stone artifacts uncannily similar to those crafted by early humans — challenging the established narrative of human cultural evolution. The monkeys — long-tailed macaques — seem to have made their artifacts by accident, not by design. (CHAIDEER MAHYUDDIN/AFP via Getty Images)The Planck group found the first evidence of macaques adapting this seafood-foraging use of stone tools to another food: nuts. In particular, the monkeys targeted the hard, oil-rich nuts of African oil palms — introduced as a cash crop across the region. Even calling the macaque-produced stone flakes “artifacts” was controversial because some scientists felt it implied an overlap between tool use by Homo sapiens and other primates that wasn’t justified.