The old happiness curve was easy to remember. It makes the actual result clearer: younger adults in these datasets are not merely missing an advantage once associated with youth. The mirror image also appeared: worry, stress and other forms of ill-being tended to rise towards middle age and fall afterwards. Why this is not quite a global happiness inversionThe title-sized version is that young people are now the least happy everywhere. The new paper’s force lies in finding a similar age gradient across several measures of ill-being, not in proving that every country now shares one happiness curve.