Institut Català de Paleontologia Miquel Crusafont (ICP-CERCA), Universitat Autònoma de Barcelona, Edifici ICTA-ICP, c/ Columnes s/n, Campus de la UAB, 08193, Cerdanyola del Vallès, Barcelona, Spain ...
Look for the sagittal suture – the squiggly line that runs the length of the skull – and note whether is it's completely fused. If it is, the remains are likely to be of someone older than 35.