ENIGMA · nEanderthal virtual boNe hIstology: deciphering hominin Growth rates, activity and environMental Adaption

A central challenge in the study of the history of humanity is to understand how evolution has shaped who we are today. Neanderthals are our closest relatives in the human evolutionary family tree. Therefore, understanding the differences and similarities between Neanderthals and Anatomically Modern Humans (AMH) is crucial for defining our phylogenetic history. Bone palaeohistology, the study of the microstructure of fossilized tissue, offers scientists a window into the past: Mineralized tissue keeps a record of an individuals' growth and adaptive responses, therefore allowing us to study aspects of life history long after fossilisation. Due to the rapid increase of cutting-edge technology of Virtual Histology, we can image the internal microstructure of bone without inflicting damage to the material. This allows for the high-resolution study of important fossils, including those of early humans. Although of such high potential, bone histology is still a highly understudied field in human anatomical evolution. In this project, I combine advanced X-ray techniques (synchrotron- and lab-based phase-contrast microtomography, synchrotron X-ray fluorescence and infrared spectroscopies) with the investigation of a large sample of skeletal elements from the Krapina Neanderthal collection (dated 130 +/- 10 kya), Croatia, to investigate detailed aspects of their developmental biology. I will do this by 1) Establishing the preservation state of the Neanderthal fossil remains, 2) Examining the speed of maturation of juvenile Neanderthals and 3) Assess the type and intensity of Neanderthal physical activity and environmental adaption. Finally, I will employ the newly acquired knowledge and skills to valorise the 3D modelling of fossil bone microstructure for museum and outreach purposes in commercial settings. The results of ENIGMA will significantly contribute to our understanding of Neanderthal biology, and with that, help us to further define what it means ‘to be human’.