Karl initially completed a BSc (Physiology) and a Bachelor of Physical Education (Hons) at the University of Otago. He then moved to the University of Calgary, Canada, where he completed a MSc and PhD in Neuroscience. In 2010 he returned to the University of Otago to undertake postdoctoral research investigating the structure and function of GnRH neurons.
Karl took up an appointment as a Lecturer in the Department of Physiology at the University of Otago in 2014. He currently runs an independent research programme focused on understanding how neurons in the paraventricular nucleus of the hypothalamus control the body’s response to stress.