Bones excavated by archaeologists in the soil can explain a great deal about the processes that occurred after animals or humans died. The study that deals with processes from the time an animal dies until it is found in an excavation is called taphonomy. For instance, sometimes bones are found which are perfectly preserved, such as mummies or bog bodies. But it also occurs that bones are completely degraded and fall apart when touched. In other words, the state of the bones is highly influenced by the type of burial environment and the processes that occurred after death. When the death cause is unkown it is crucial to reconstruct these processes.
On the island of Mauritius, two locations containing bones are of interest for this study. In the marsh of Mare aux Songes a massive unit of bone material has been found, dating to 4000 years B.P. These animals died naturally. On the same island, just a little further north, a Dutch fortress from the 17th century is present, which also contained many bones. Here the bones represent slaughtered animals. Even though much younger, these bones looked less well preserved than the bones from the Mare aux Songes. This is strange, because we expect the younger bones to show better preservation. So, this is probably due to the differences in burial environment.
A comparison between the two sites can show very interesting results.
How do we study the bones?
We make thin-sections for the microscope, this can show several features at
microscale such as cracks. Also some chemical analyses will be done to study the composition of the bone and the presence of proteins.
What is the relevance?
Its still a mystery why and how dodos and other animals died at the Mare aux Songes. Investigating the bones will shed light on what happend after death and help to reconstruct the conditions of death. Further the state of the bones is vital for decisions concerning what to do with the site. Bad preservation may require excavation, while good preservation can indicate that the bones are in good quality environment and can remain untouched.
Also, this type of research may give insight in the possibilities to do research in the future on biomolecules and assess whether for instance dodo dna is still preserved! With the naked eye a bone may look well preserved and seem likely to contain proteins and DNA, but this is not always the case. A microscopical view can tell a complete different story.
Finally, bones are the closest we can get to extinct species, such as the dodo and giant tortoises. The study helps to understand how they lived and die. It is therefore a good thing to study them as much as we can.
Laura van der Sluis (Msc student Bio-Archeology at Free University Amsterdam VU)