Accurate depiction of uncertainty in ancient DNA research: The case of Neandertal ancestry in Africa

Abstract

All approaches to understanding the past must work with limited data. Like many other kinds of evidence of past peoples, the relation between ancient DNA and past events is intermediated by complex models that bear many assumptions, some untested or untestable. Statements about the past from this evidence are thus accompanied by uncertainty, some quantified and some unquantifiable. Accurate communication of this uncertainty is essential to effective cross-disciplinary collaboration and public understanding. Here I examine one well-studied case of ancient DNA inference: the inference of Neandertal ancestry for today’s African peoples. In this case study, scientific predictions about Neandertal introgression and the genetic variation of all living people both gave consistent predictions before the sequencing of Neandertal DNA. Still, at the time that a draft Neandertal genome was published, a myth became established among the public that today’s Africans are different from all other living humans in that they lack Neandertal ancestors. This contribution reviews public statements, press releases, and press accounts to understand the origin of this story and why it became widespread. I review the ultimate impact of this story and the path toward correcting it. In light of this example, I provide some guidelines on how to recognize accurate depiction of uncertainty and examples of how effective engagement with content experts in archaeology and biological anthropology can lead to stronger and more easily communicated scientific outcomes.