A five-year controversy between archaeologists and paleontologists has finally been resolved over whether marks found on 3.4 million-year-old bones were made from stone tools or trampling. A new analysis confirms that stone tools were used to create the marks, effectively ending the debate and starting a new perspective on tool-use in early hominins.
Stone Tools Responsible for Marks on Fossil Bones in Dikika
After extensive analysis using statistical methods and experimental data to recreate trampling on bones, a new study published in the Journal of Human Evolution has concluded that the marks on two animal bones were made by stone tools in a form of butchery rather than by trampling.
The fossil bones that are over 3.4 million years old were found in Dikika, Ethiopia in 2010 and had started a heated debate regarding the origins of stone tool use in our early hominin ancestors that has had scientists butting heads for 5 years.
The study conducted by Emory University assistant professor of anthropology Jessica Thompson has not only confirmed the use of stone tools, but has also developed novel methods of analysis in fieldwork for paleoanthropology.
The Beginning and End to the Stone Tool Versus Trampling Controversy
The newest analysis of the two fossils bones has ended the controversy of the origin of the 12 marks scraped into the specimens. One specimen is a long bone believed to come from a medium-sized animal such as an antelope, while the other is a rib bone from a considerably larger animal, maybe similar to a buffalo.
The study says the marks were made with a combination of cutting and hitting. Thompson believes the bones were hit multiple times with a tremendous force. Imagine you had a crude tool, a sharpened stone perhaps, and needed to hack off meat from the bone. You’d get marks that resemble the ones found on the ancient bones.
The findings support the original study published in the journal Nature in June 2010. It also refutes the belief that the bones were trampled, as suggested by a rebuttal study published in December 2010 in the Proceedings of National Sciences (PNAS).
While the original interpretation was groundbreaking as it had effectively pushed back the understanding of stone tool use by early hominins by 800,000 years, this study has fueled the flames to the radical discovery that our genus Homo may have not been the first to use butchery tools.
Homo wasn’t the first hominid to use stone tools
The importance of these 12 marks on the two bones over 3 million years old is that they will change our current views of stone tool use and human evolution.
Previously, the earliest evidence of stone tool use has been found to be only 2.6 million years ago, which coincides so well with the emergence of our genus nearly 2.8 million years ago. It is believed that as we evolved, our diets and our brain size evolved simultaneously, possibly from the use of stone tools to allow us to eat more meat.
However, the bones from Dikika come from the same area and same time frame as the hominid species fossils of Australopithecus afarensis. This finding can completely set back human evolutionary studies by over one million years in regards to stone tool use and the origins of meat-eating in early hominids.
Stone Tools Used on Fossil Bones at Dikika Represent Turning Point in Paleoanthropology
In order to examine the effects of trampling, the researchers analyzed over 4,000 bones from the same area. Some of these bones’ surfaces revealed evidence of trampling, while the researchers used experimental techniques to make trampling marks to compare them to the original specimens.
The two bones’ marks were unique to the trampling marks of the others from a number of factors, including something as tiny as the angularity of sand grains against the bones. It was found, conclusively, that these bones had not been trampled.
Though these are only two bones out of thousands that have yet to be studied or even found, this study and the proceeding, original one represents a huge milestone for paleoanthropology. Whether the use of stone tools was still rare at the time or whether there is more evidence to find, our understanding of stone tool use in hominin evolution has already started to evolve.
Title picture of bone marks analyzed from the Dikika site is credited to Zeresenay Alemseged.
Additional image of Australopithecus afarensis, Credit to Tim Evanson.