PRE-HISTORY

The first menstrual tracker

Menstruation may well be one of the oldest concerns of humanity. The Ishango bone is a 22,000 year old bone with carved tally marks that was found in present-day Democratic Republic of Congo. It was discovered by Belgian geologists whilst colonialist Belgium occupied the area.

The tally marks on the bone appear to follow a pattern, and archaeologists have long theorised that it might be a mathematical tool for prime numbers or decimals, or for tracking the lunar calendar. But perhaps it is far more likely it was charting something else that also has a 28 day cycle. It took almost 30 years for American anthropologist, Claudia Zaslavsky, to propose another possibility – a menstrual tracker.

Ishango bone, Royal Belgian Institute of Natural Sciences, Image: Joey Kentin (CC-BY-SA-4.0)