SMART NEWS

Shrew-Eating Scientists Show Humans Can Digest Bone

Scientists set out to measure how well we digest bone by swallowing a whole shrew, but was that really necessary?

October 9, 2012

Photo: Flickr user postbear

Can humans digest bone? Back in 1994, some curious researchers decided to put this question to the test by eating and excreting a northern short-tailed shrew (without the tail).

The Guardian elaborates on this odd experiment:

This was, in technical terms, “a preliminary study of human digestive effects on a small insectivore skeleton”, with “a brief discussion of the results and their archaeological implications”.

The shrew was a local specimen, procured via trapping at an unspecified location not far from the school . For the experiment’s input, preparation was exacting. After being skinned and eviscerated, the report says, “the carcass was lightly boiled for approximately 2 minutes and swallowed without mastication in hind and fore limb, head, and body and tail portions”.

From there, the researchers collected all of their fecal matter over the following three days. They stirred the feces in a pan of warm water until it disintegrated, then filtered the solution through a quadruple-layered cheesecloth mesh. After rinsing their recovered treasures with a detergent solution, the examined the contents for any traces of bone, magnifying the bits from ten to 1,000 times.

But despite extraordinary efforts to find and account for each bone at journey’s end, many went missing. One of the major jawbones disappeared. So did four of the 12 molar teeth, several of the major leg and foot bones, nearly all of the toe bones, and all but one of the 31 vertebrae. And the skull, reputedly a very hard chunk of bone, emerged with what the report calls “significant damage”.

The scientists were shocked at the results, attributing the dissolved remains to the acidic, churning environment of the stomach. They argue that this finding has implications for archaeologists, who make assumptions about what ancient peoples ate based upon the animal bones they dig up.

Anthropologists have long known that humans ate whole bones and animals, however, leading readers to wonder if the shrew-eating scientists just wanted to eat a shrew to see what would happen. From anthropologist John Speth:

Well-preserved prehistoric human coprolites (feces) recovered in large numbers from dry caves throughout western North America are full of pulverized bone fragments, including pieces of broken skulls, as well as fur and feathers, indicating that rodents, rabbits, birds, lizards, snakes, and amphibians were often cooked whole, pounded in a wooden mortar or on a milling stone, and then consumed in their entirety – bones, fur, feathers, and all, including the precious DHA in the brains.

In any event, at some point in human evolution, the blog HuntGatherLove points out, humans’ ability to extract nutrients from bones using tools surpassed their body’s ability to access those nutrients unaided. Archaeologists refer to this phenomenon as “grease processing”—a cooking technique that likely resembled modern bone-based broths.