The Bone Crunchers
Source: Johan du Toit, Carrie Hampton, BBC Wildlife, July, 2002, 20(7):58.
The giraffe is a herbivore that lives in Africa. It mainly eats the leaves on bushes and leaves from the acacia trees that grow on the savanna. Their long necks provide the giraffe with exclusive access to the tops of the trees. In Zimbabwe, though, there has been strange sightings of an abnormal behavior in these giraffes and the people there have come to fear them. There have been many sightings of giraffes eating bones from the remains of animals that the local predators have felled. �The image of a giraffe with the vertebral column of a gazelle hanging from its mouth is...[a horrifying and grotesque sight]� Though the giraffes diet provides the nutrients and moisture that the giraffe needs to survive it is hypothesized that the need of minerals and salts needed, especially by nursing animals, is not sufficient in their normal diet. It is true that giraffes need a sufficient amount of calcium to maintain the massive growth of their skeletons that could be provided by the eating of bones. It is also possible that the osteophagia or bone-eating could be caused by the need for these particular minerals. Though it is not likely that the giraffes can receive the sufficient nutrients from this, due to their specialized herbivore stomachs, it is possible that this need for the correct nutrients can drive it to eat the bones anyway.
As you can see, there is something deathly wrong with this picture. Why would a giraffe have the need to eat bones in the first place? The answer is simple, they are not getting the nutrients they need from their environment. It is true that the savannas are slowly and in some areas quickly disappearing to create farmland for people, pastures for cows, and for development. This disappearing of habitat is also a disappearing of food supply and nutrients in the soil. If the lands are being farmed the soil is loosing it�s nutrients and in turn the plants are too. The giraffe eats these plants and trees that are left after the pasture or field is done with and are not receiving sufficient amounts of the nutrients they need to grow and to raise their young. This causes a problem. Where do they find the nutrients they need? I am not sure how they first came to the idea that eating bones of dead carcasses would help them, but obviously they did. Somehow some of their survival instinct lead them to this. Is it working? No, the giraffe is not a carnivore and it is not adapted to being a carnivore, so it is impossible for this animal to receive a sufficient amount of needed nutrients from this behavior. It�s body is adapted for plants and digesting plants. For it to be able to digest bone in a way to receive all the nutrients it would need a different body chemistry in it�s stomach and intestines to do so.
Another thing that could be possible in explaining this behavior is a genetic defect. Like humans a giraffe has a brain, a nervous system, and DNA that runs this and all it�s other body functions. It is possible that a this certain behavior can be caused by a defect in a part of the brain. Just like some humans have odd cravings due to drugs or birth defect, a giraffe can have this same strange affinity towards cravings unnatural. This could be due to pollution caused by humans in the air, soil, or water. For example, some humans if they are exposed to a certain drug start to have cravings to eat things such as paint chips or cigarette butts. To explain the many giraffes that are doing this, it is possible that a prominent male in the giraffe community carries a gene for this particular trait and is passing it on to his offspring. The offspring in turn would display the same affinity toward eating bones and so on. Hopefully this is isolated to Zimbabwe so it will not contaminate the rest of the species, if this is the case.
Also during pregnancy a mother might crave something normal like chocolate or she could crave things unnatural to eat. This is a phenomenon called pica. They could crave lead, detergent, or even dirt. This could theoretically happen in giraffes too. It was mentioned in the article that this was seen happening when the mother was pregnant or nursing. Could this behavior be caused by the hormone imbalance of pregnancy? Maybe not but it seems that this is the most likely of the answers listed.
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