Getting species diagnoses non-destructively from collagen

2 minute read

A neat paper by Naomi Martisius and coworkers in Scientific Reports: “Non-destructive ZooMS identification reveals strategic bone tool raw material selection by Neandertals”.

The introduction of the paper presents the problem that the researchers set out to solve. How can we get biological identifications of modified bone fragments without drilling into them to extract protein? The answer is provided by a new method that can examine the trace amounts of collagen that adhere to plastic surfaces after they contact a bone. This includes the plastic bags that are used to store artifacts and archaeological bone samples.

ZooMS has been useful for identifying ancient animal remains when fragmentary bones present a challenge for more traditional methods. The method has been used to identify fragmented animal and human remains from Paleolithic sites, as well as cultural artifacts from various time periods, including bone tools and parchment. Such objects frequently have been significantly altered from their original form making taxonomic identifications based on morphology nearly impossible. At the same time, conventional ZooMS extraction procedures involve drilling or cutting a bone sample (less than 20 mg), thereby altering often unique and fragile artifacts (Supplementary Fig. S1). Recently, a non-destructive approach based on the triboelectric effect occurring between collagen and plastic surfaces has been developed to sample parchment for ZooMS analysis. The concept behind this approach has been applied to plastic storage bags containing bone artifacts as well, as the use of erasers carries the risk of modifying bone surfaces through abrasion. Here, we show that collagen molecules adhering to the plastic surfaces allow us to infer species selection of Middle Paleolithic lissoirs made by Neandertals, which then permits the consideration of competing hypotheses about the selection of ribs as the raw material for making lissoirs.

This is a significant advance. For those of us who grapple with decisions about destructive sampling, every non-destructive approach provides us with the potential of making better decisions. It won’t always be the right thing to use these non-destructive approaches. Some biological and anthropological questions will merit a fuller examination of larger samples. But the availability of a non-destructive method means that we can be deliberate in choosing the best method for each scientific question. We can better leverage the knowledge we gain from some samples to conserve others.

The result of the study is itself interesting. The fact that Neandertals were consistently choosing bovid ribs for these specialized tools, even though bovid remains are rare at the site, gives useful insight into the entire process behind their use of technology. They planned for later use of tools and curated material to make effective use of hides from later kills.