Pre-Columbian civilizations

Incan numerical recordkeeping system may have been widely used

ancient people did stuff, anthropology, Archaeology, inca, Incan empire, indigenous americans, indigenous communities, indigenous south america, khipu, Pre-Columbian civilizations, Science, wari / Paul Patrick / August 14, 2025

Women in STEM: Inca Edition

In the late 1500s, a few decades after the khipu in this recent study was made, an Indigenous chronicler named Guaman Poma de Ayala described how older women used khipu to “keep track of everything” in aqllawasai: places that basically functioned as finishing schools for Inca girls. Teenage girls, chosen by local nobles, were sent away to live in seclusion at the aqllawasai to weave cloth, brew chicha, and prepare food for ritual feasts.

What happened to the girls after aqllawasai graduation was a mixed bag. Some of them were married (or given as concubines) to Inca nobles, others became priestesses, and some ended up as human sacrifices. But some of them actually got to go home again, and they probably took their knowledge of khipu with them.

“I think this is the likely way in which khipu literacy made it into the countryside and the villages,” said Hyland. “These women, who were not necessarily elite, taught it to their children, etc.” That may be where the maker of KH0631 learned their skills: either in an aqllawasai or from a graduate of one (we still don’t know this particular khipu-maker’s gender).

“Science confirming what they already knew”

The finely crafted khipu turning out to be the work of a commoner shows that numeracy was widespread and surprisingly egalitarian in the Inca empire, but it also reveals a centuries-long thread connecting the Inca and their descendants.

Modern people—the descendants of the Inca—still use khipu today in some parts of Peru and Chile. Some scholars (mostly non-Indigenous ones) have argued that these modern khipu weren’t really based on knowledge passed down for centuries but were instead just a clumsy attempt to copy the Inca technology. But if commoners were using khipu in the Inca empire, it makes sense for that knowledge to have been passed down to modern villagers.

“It points to a continuity between Inka and modern khipus,” said Hyland. “In the few modern villages with living khipu traditions, they already believe in this continuity, so it would be the case of science confirming what they already know.”

Science Advances, 2025. DOI: 10.1126/sciadv.adv1950 (About DOIs).

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Ancient fish-trapping network supported the rise of Maya civilization

Harrison-Buck and her colleagues calculated that at its peak, the system could have produced enough fish each year to feed around 15,000 people. That’s based on modern estimates of how many kilograms of fish people eat every year, combined with measurements of how many kilograms of fish people in Zambia harvest with similar traps. Of course, people at Crooked Tree would have needed to preserve the fish somehow, probably by salting, drying, or smoking them.

“Fisheries were more than capable of supporting year-round sedentarism and the emergence of complex society characteristic of Pre-Columbian Maya civilization in this area,” write Harrison-Buck and her colleagues.

When we think about the Maya economy, we think of canal networks and ditched or terraced fields. In just one patch of what’s now Guatemala, a lidar survey revealed that Maya farmers drained thousands of acres of swampy wetland and built raised fields for maize, crossed by a grid of irrigation canals. To feed the ancient city of Holmul, the Maya turned a swamp into a breadbasket. But at least some of their precursors may have made it big on fish, not grain. The common feature, though, is an absolute lack of any chill whatsoever when it came to re-engineering whole landscapes to produce food.

This Google Earth image shows the area containing the ancient fishery.

Infrastructure built to last and last

From the ground, the channels that funneled fish into nearby ponds are nearly invisible today. But from above, especially during the dry season, they stand in stark contrast to the land around them, because vegetation grows rich and green in the moist soil at the base of the channels, even while everything around it dries up. That made aerial photography the perfect way to map them.