The bone that began the space odyssey (Q2564032)

The article describes the Ishango bone, an artefact possibly 11000 years old and carrying an ordered sequence of differentiated notches; it gives a brief account of the origin of the bone, and reports the arithmetical and calendaric-observational interpretations suggested, respectively, by J. de Heinzelin and A. Marshack, pointing out wisely that they must be presumed to be mutually exclusive.