My principal research aim is to determine where, when and why modern humans evolved an extended ~20 year period of growth and development. To research this problem I have pioneered ways of studying incremental markings in fossil primate tooth tissues. Teeth are abundant in the fossil record and contain incremental markings that allow us to retrieve information about the rates of and direction of cell movement during tooth development. Some of the mechanisms of morphological change during human evolution have been described in this way and it has been possible to determine the timing of key events during the period of growth and development in certain fossil primates. This research theme drives an extensive international interdisciplinary research effort with collaborations that draw on clinical science, comparative anatomy and palaeoanthropology.