Mathematics, Menstruation, and the Myths of History

"Ishango bone discovered in East Africa is one of the earliest examples of a lunar calendar indicating men's need to record days and months to understand seasonal changes for agriculture." When we read the quote, do we feel like looking it up and checking if this is a fact? How about this: "Ishango bone discovered in East Africa is one of the earliest examples of a lunar calendar indicating women's needs to record days and months to understand the menstrual cycle and the possibility of pregnancy." Now all the factual enthusiasts, including us, are curious to know if this is, in fact, true.

This has been a debate going on for years now. This debate, far from being a simple academic squabble, underscores a broader historical narrative: the overlooked contributions of women to early mathematics, calendars, and agriculture.

An illustration of Ishango bone

Ethno-mathematician Claudia Zaslavsky argued that the Ishango bone originated with women’s need for a lunar calendar. In her view, keeping track of menstrual cycles and fertility may have necessitated such innovations. "Who but a woman keeping track of her cycles would need a lunar calendar?" Zaslavsky asked.This perspective challenges the traditional narrative that early mathematical tools were created solely for purposes like trade or hunting, domains often dominated by men in historical accounts.

 It is equally possible that the Ishango bone was a lunar calendar (in that case probably made and used by women) or a tally bone used for basic arithmetic understanding, like many others that have been discovered, which could have been used by men or women. Some of you might have even seen a meme discussing a similar idea—that the first mathematicians and astronomers were women trying to track their cycles.

The concept of tracking menstruation predates modern apps and technology. From the Suri of Ethiopia, who used knotted ropes, to the Yurok tribe of North America, where women tracked cycles with daily sticks, menstrual calendars have existed across cultures. In Siberia, Nganasan women marked the ten months of pregnancy with colorful strips of fabric, while Scandinavian primstav sticks recorded lunar phases and festivals.

Even linguistic evidence suggests a deep connection between menstruation and the development of timekeeping. The Gaelic word for menstruation, miosach, also means calculation, and the Romans referred to the measurement of time as “menstruation.” Feminist scholar Barbara G. Walker proposed that calendar consciousness began with women, as their natural body rhythms correlated with lunar phases.

The idea that we are trying to put forth here is not about proving who invented what; it’s about rethinking the contributions women have made to civilization. For too long, history has overlooked their role, whether in agriculture, mathematics, or understanding the relationship between the external world and their own bodies.

Written by Janaky S. and edited by Janaky S. and Parvathy R. @ThinkHer

References

1.https://www.math.buffalo.edu/mad/Ancient-Africa/ishango.html

2.https://oliviacampbell.substack.com/p/how-period-tracking-birthed-the-calendar

3.https://aaregistry.org/story/math-artifact-ishango-bone-discovered/