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Bone markings: Something for scientists to chew on

Nile crocodile (Crocodylus niloticus) manipulating a carcass of a cow prior to ingestion at a crocodile farm in Bagamoyo, Tanzania. Sharp, pointed teeth can inflict deep grooves with V-shaped cross sections that mimic cut marks.
[Image courtesy of J.K. Njau]

Many fossil animal bones have been dinged up by natural processes, chewed by carnivorous animals or cut by human tools. But, when researchers dig up these bones millions of years later, it can be really difficult to tell these different types of marks apart.

Jackson Njau of Indiana University warns researchers about this problem in an article published in 6 April 2012 issue of the journal Science.

If the animals lived the same time as modern humans or our earlier ancestors shared, it's especially important to get this right, he says. Mistakenly concluding that human blades cut an ancient bone, when really the cuts were from a hungry animal, can throw off archaeological interpretations of early human behavior. (It's generally thought that the world's oldest tools and butchered bones originated in Ethiopia approximately 2.6 million years ago.)

In his article, Njau says that researchers should compile and use a standard checklist of sorts, which would help everyone distinguish the marks of human tools from the feeding traces or trampling hooves of other animals, in the same way.