Around 7,000 years ago in China’s Central Plains, the Yangshao culture began to flourish along the Yellow River. It was another example of the same widespread Neolithic culture that was also emerging in Europe around the time, with new developments in pottery and agriculture. In China, it dominated the region for approximately 2,000 years.

Yangshao remains have offered a team of international researchers insight into an interesting question: did gender differences change alongside agricultural practices? They argue that gender inequality emerged along with the new crops among the Yangshao. The archaeological data has some interesting signs, but it's possible that the researchers are overstating their case: the only evidence they have is of inequality in people's diets, which doesn't tell us much about the structure of inequality of societies.

Millet cereals were domesticated in the region as early as 10,000 years ago and were the primary crop of Yangshao cultures. Wheat, barley, and soybeans were introduced to the region after the end of Yangshao, around 4,000 years ago, although archaeological traces of them remain low for centuries. According to historical records, they were thought to be inferior foods, suitable only for protecting the poor against famine. That only changed around 2,000 years ago, when improved technological methods made it easier to refine them.

Agricultural changes aren't only reflected in artifacts; they show up in excavated bones, too. Millet uses a type of photosynthesis that differs from the vast majority of plants, and it’s the only domesticated plant in Early China to use this type of photosynthesis. The result of this is that the carbon signature in the bones of people who ate primarily millet looks different from that of people who ate other plants. Nitrogen traces in bones can point to the quantity of animal products in an individual's diet.

The researchers compared Yangshao bones with remains from the Bronze Age Eastern Zhou Dynasty, which lasted from 771 to 221 BC. In the Eastern Zhou bones, they found evidence that men and women were eating different diets: men’s bones had evidence of higher consumption of animal products and millet, while women’s bones showed evidence of higher consumption of the more recent (and scorned) crops of wheat, barley, and soy. The Yangshao bones, on the other hand, generally didn’t show a significant difference, with the exception of one of the five sites studied. This suggests that “meals were no longer shared at the household level during Eastern Zhou,” the authors write.

On its own, this is not evidence of a bias favoring males. There could be cultural reasons for a gender-based split in diet that weren’t actively bad for women—although the fact that women were eating more of the food that was considered low quality is a bit telling.

But other strands of evidence corroborate the inequality story: women’s bones from Eastern Zhou, but not Yangshao, showed more signs of childhood malnutrition, and size differences between the sexes increased from Yangshao to Eastern Zhou. Both of these signs indicate that male children had better quality food, pointing to greater parental investment in male children. And female graves in Eastern Zhou had fewer burial items and were less likely to have a coffin than male graves, while again, Yangshao graves were more egalitarian.

It’s an interesting result, but it’s always a mistake to draw too many parallels with modern society from archaeological research. It’s also not clear that this is really evidence of the first emergence of gender inequality in this region of China.

It is evidence of a massive cultural change in how the genders related to each other, certainly. But food-based inequality isn’t the only kind of gender inequality that a society might practice—there are plenty of inarguably patriarchal modern societies where families eat meals together. It’s entirely possible that Yangshao did have inequality, but that it took a different shape and would have left a different kind of archaeological presence.

An open question is how the change in gender practices and agriculture are interwoven. Did the change in agriculture itself lead to the change in gender norms? The causal story is likely to be complicated, and the authors of the paper steer clear of suggesting that one led to the other, but the relationship between them is something that future research can hopefully illuminate.

PNAS, 2016. DOI: 10.1073/pnas.1611742114 (About DOIs).