During the final two centuries of the Shang Dynasty (1600-1046 BCE) in China, thousands of people were sacrificed at the state capital of Yinxu. Some were dispatched with great fanfare, buried with rich grave goods, while others appear to have been sacrificed with extreme prejudice and mutilated after death. Now, a new study sheds some light on these victims. Simon Fraser University bioarchaeologist Christina Cheung and her colleagues reconstructed these ancient people's' lives by discovering what they ate and when, based on chemical signatures left in their bones.

Human sacrifice was a common ritual among the people of almost every ancient civilization, from China and Europe, to Mesopotamia and the Americas. Though archaeologists have analyzed the graves of these sacrifices, they have many questions about the victims' lives. Were they revered and celebrated before death, or were they outcasts? Were they prisoners from far away, or were they the sons and daughters of their executioners?

Cheung and her team answered a number of these questions with a chemical analysis of the bones of 68 sacrificial victims at Yinxu, which were compared with the bones of 39 locals. All of the victims were male, and most were young.

Sacrifices were buried in the royal cemetery across the Huan River from the palace. Archaeologists have been excavating at this site for almost a century, uncovering more than 3,000 sacrificial victims who appear to have been dispatched in groups of 50 to 350 at a time. In a recent paper for Journal of Anthropological Archaeology, Cheung and colleagues describe two distinct types of sacrificial victim.

In Shang, China, there were two main types of human sacrifice: rensheng (人牲) and renxun (人殉). Rensheng literally means "human offerings," and these victims were often buried in large groups, mutilated, and with little to no grave goods. Renxun can be loosely translated as "human companions." They were often buried with elaborate grave goods, individual coffins, and even their own rensheng.

Archaeologists typically find rensheng in mass graves that they divide into "skull pits," "headless pits," and "mutilated pits." As you might guess, these are pits full of skulls, decapitated bodies, and partial bodies, respectively. Unfortunately it's often hard to tell the difference between rensheng and renxun because there has been so much looting and excavation at Yinxu. The practice of mutilating the bodies also makes it difficult for scientists to match skulls with bodies, so they relied entirely on skeletons (headless or otherwise) to identify individuals.

How bones reveal diet

Knowing what people ate reveals a lot about who they were and where they lived. Cheung and her colleagues analyzed carbon, nitrogen, and sulfur isotopes in the bone collagen from each person. These isotopes give hints about the kinds of vegetables and proteins they ate, as well as where they drank water. By combining all three readings, scientists can get a unique signature that tells them where and what a person ate over an extended period of time.

The most interesting part is that different bones reveal diet and location for varied periods of time. The researchers explain:

As bone collagen turns over slowly, the carbon and nitrogen isotope values measured in bone collagen reflect the long-term averages of diet over an individual’s lifetime. Small bones or those consisting mostly of trabecular bone, such as ribs, turn over faster than larger, denser bones such as femora. The general consensus is that rib turnover occurs at approximately 3–5 year intervals, while adult femoral collagen almost never turn over completely... The differing turnover rates in different skeletal elements have enabled archaeologists to look for evidence of migration in the form of drastically changing diets over an individual’s lifetime.

Cheung and colleagues analyzed two bones from each individual, looking for these longer-term signatures and shorter-term ones. What they found was that the human sacrifices were clearly not locals. Isotopic signatures in their larger bones were dramatically different from those of local people, so they had grown up in another region, eating different foods. At the same time, many of the sacrifices had similar sulfur readings, indicating that they may have come from the same region, perhaps from the same state or nation.

Smaller bones from the sacrifices show that their diets changed quite a bit in the last few years of their lives, coming to resemble the diets of locals. That said, they were not eating as well as their neighbors. Their meals contained a lot of millet and very little animal protein. Indeed, nitrogen isotope readings show their diets contained less meat protein than even the poorest local people. That suggests they were treated as the lowest members of the community.

Anthropologists have a long-running debate about whether these people were prisoners or actually worked as slaves in the city that surrounded the palace. Obviously we can't know this based on their diets, but it does seem unlikely that the people of Yinxu would have kept these prisoners around for years without making them work. So they probably did some labor, nourished on a diet of gruel and a few bites of deer meat.

Slaves, sacrifices, and state power

These findings fit what we know from written records from Shang Dynasty, which suggest that human sacrifices weren't made simply whenever prisoners were captured. Instead, there seems to have been a pool of potential sacrifices that nobles could draw upon on request. Cheung and her colleagues explain:

The early Shang scholar Yang reported that on more than one occasion, Shang nobles and vassals had to ask for the king’s permission to offer captives to the king for sacrifice, and only after consulting an oracle would the king demand a specific date for the delivery of such captives. Yang thus argued that war captives were offered for sacrifice upon request, not upon availability.

Shang Dynasty writings also say that human sacrifices were prisoners of war. Many records mention sacrificing people from a group called Qiang, though researchers are uncertain whether this was a specific group or just referred to all enemies west of Yinxu. Regardless of who the Qiang were, there is a remarkable homogeneity to the chemical signatures in the bones of Yinxu sacrifices the researchers examined. They were clearly from the same general region.

One debate remains unresolved: why did the Shang Dynasty demand human sacrifice? One hypothesis holds that leaders sacrifice people to consolidate state power. Sacrificing representatives of the enemy makes for a good show of strength and aggressiveness. But another hypothesis is that human sacrifice only comes when a state is suffering from instability, and leaders want to put on a brave show for the public.

We can't say for sure what was happening in Yinxu that made human sacrifice seem appealing. Were these early leaders of China trying to build a new state, based on their ruthless strength? Or were they worried that their control was slipping and offering sacrifices to regain an earlier greatness?

All we know is that the Shang Dynasty kept a prison full of outcasts readily available so that at any time the public could be witness to the public sacrifices of people their leaders called foes.

Journal of Anthropological Archaeology, 2017. DOI: 10.1016/j.jaa.2017.05.006