Kristal wasn’t buying it, though. His skepticism for any of those proposed functions stemmed from the complete absence of any valid research on the topic. He and his colleagues set out to investigate placentophagy in non-humans experimentally—in this case, lab rats. As happens frequently, the results of their experiments supported none of the earlier hypotheses. Kristal did suggest, though, that the previously proposed functions of placentophagy might provide secondary benefits, if they existed at all.
“The main thing that we found during our studies turned out to be an opiate-enhancing property,” Kristal said. He explained that placenta consumption by new rat moms appeared to increase the effectiveness of natural pain-relieving substances (opioid peptides) produced by the body. He added that that these enhanced analgesic effects lasted throughout the birth interval between individual “kittens” in a litter—an important point since rats generally give birth to seven to ten individuals.40
Kristal also told me that the results of a second set of experiments linked afterbirth consumption (by rat moms) to a form of reward for parental care. Briefly, the central nervous system, pituitary gland, digestive tract, and other organs secrete pain-blocking peptides like endorphins, enkephalins, and dynorphins, which have been used to explain terms like “runner’s high” and “second wind,” as well as the phenomenon in which gravely wounded individuals report feeling little or no pain. Kristal’s experiments indicated that those mothers who consumed their afterbirth received enhanced benefits from these natural painkillers, essentially getting an anesthetic reward for initiating maternal behavior like cleaning their pups.
I asked Kristal how long humans had been practicing placentophagy and how widespread the practice was. “I haven’t discovered any human cultures where it’s done regularly,” he told me. “When placenta-eating is mentioned, it’s usually in the form of a taboo. You have cultures saying things like ‘Animals do it and we’re not animals, so we shouldn’t do it.’ ”
In 2010, researchers at the University of Nevada, Las Vegas, searched an ethnographic database of 179 preindustrial societies for any evidence of placenta consumption. Searching for the terms “placenta” and “afterbirth” in the electronic Human Relations Area Files (eHRAF), described as “the gold standard for cross-cultural comparative research,” they found 109 references related to the special treatment and/or disposal of placentas. The most common practice (seen in 15 percent of accounts) was disposal without burial (examples include “throwing it into a lake”), followed by “burial” (9 percent). The latter narrowly beat out my personal favorite “hanging or placing the placenta in a tree” (8 percent). What the UNLV researchers did not find was a single instance of a cultural tradition associated with the consumption of placentas by moms—or anyone else, for that matter.
Considering the ubiquitous nature of placentophagy in mammals, including chimps, our closest non-human relatives, I was surprised they were unable to find at least one culture somewhere where placentas were regularly eaten. I mentioned to Kristal that I’d run across an example of placentophagy in the Great Pharmacopoiea of 1596 (a go-to guide for many New Yorkers seeking medical advice), wherein Li Shih-chen recommended that those suffering from ch’i exhaustion (whose embarrassing symptoms included “coldness of the sexual organs with involuntary ejaculation of semen”) partake in a mixture of human milk and placental tissue.
“It is an ingredient in herbal medicine,” Kristal said. “In fact, there are a lot of placentophagia/midwife/doula websites where two things come up repeatedly. One—the benefits that I found in my research, which we never extrapolated to humans, and two—the [mistaken] idea that it’s been done for centuries in China.” 41
“So has it?” I asked.
“Only rarely,” he replied. “The other thing is that we don’t know if it works. In terms of Chinese medicine, there are thousands and thousands of preparations whose efficacies have never been tested empirically. Nowadays there’s a rule of thumb, which I don’t agree with, that if the Chinese use it in herbal medicine, it must work. That’s really a silly attitude. But I wouldn’t call the Chinese a placentophagic society.”
On a more recent and Western note, I had also come across a report that in rural Poland in the mid-20th century, peasants “dry [placenta] and use it in powdered form as medicine, or the dried cord may be saved and given to the child when he goes to school for the first time, to make him a good scholar.” I ran this by my Polish bat biologist colleague Wieslaw Bogdanowicz, who did a bit of investigation himself (presumably asking some of the peasants he knew if they’d heard of such a practice). The answer came back “nie,” with my friend telling me it was probably safe to assume that the iPad had overtaken the uCord as an educational tool.