Kivell, Tracy L. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Max Planck Society;
Kivell, T. L., & Schmitt, D. (2009). Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor. PNAS, 106(34), 14241-14246. doi:10.1073/pnas.0901280106.