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paleoanthropology, genetics and evolution

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Tracing the users of chimpanzee tools by their DNA fingerprints

A new paper by Fiona Stewart and coworkers does a bit of forensic DNA analysis on tools made and used by chimpanzees: “DNA recovery from wild chimpanzee tools”.

The authors collected termite fishing tools used by eastern chimpanzees in the Issa Valley, Tanzania. Over a span of two months, they kept track of thirty termite mounds, collecting any tools that the chimpanzees left there. They also collected fecal samples throughout the field site, identifying at least 67 individuals.

They collected 49 tools, and were able to get mitochondrial DNA haplotypes from 41 of them. They were able to get enough DNA to type microsatellites on 18 of the tools, which were made and used by 11 different chimpanzees in total.

Archaeologically, this ability to track an individual’s use of specific tools over that time is the equivalent of attempting to track the products of an individual stone knapper at a Palaeolithic human site [e.g., 45], but with the added detail and linkages provided by the genetic data. We anticipate that the routine and long-term application of our methods at a single site would reveal the links between social and genetic influences on tool selection and modification at a level that is currently unobtainable.

I think this work is really cool.

Obviously there is limited direct utility to getting DNA from tools at sites where behavioral ecologists track the chimpanzees and record their tool use.

But across broader areas of Africa, it would be really helpful to be able to examine tool use in areas where the chimpanzees have never been habituated or tracked by primatologists.

More interesting, chimpanzees usually learn how to make and use tools from their mothers. That means that the traditions of toolmaking may correspond to mitochondrial lineages over at least short time spans. If those traditions are mainly spread and maintained by females moving among groups, there may be long-lasting associations of mtDNA haplotypes that can be tracked over hundreds or even thousands of years.

That raises the potential of looking at different kinds of chimpanzee tool use on a multigenerational or even millennial time scale, without even having to habituate the chimpanzees.

Again, pretty cool!

Reference

Stewart FA, Piel AK, Luncz L, Osborn J, Li Y, Hahn BH, et al. (2018) DNA recovery from wild chimpanzee tools. PLoS ONE 13(1): e0189657. https://doi.org/10.1371/journal.pone.0189657