A New Human Ancestor Has Been Named

A team of researchers has assigned a new name for an ancient human ancestor. They believe this will help to resolve "the muddle in the middle", a research conundrum that has caused conflict in the study of human evolution. Their work is published in Evolutionary Anthropology Issues News and Reviews.

The importance of names

Nomenclature – assigning names or terms – is incredibly important in science for many reasons, but largely because scientific research is a global endeavor. Let's picture two researchers that are conducting experiments using the same organism, but in two different parts of the world. If one scientist refers to the organism as "X", and the other decides to name it "Y", their publications may be on the same organism, but they would not necessarily know. Nomenclature is important for succinct communication, particularly in the study of ancient species and human evolution, palaeoanthropologist Professor Mirjana Roksandic told Technology Networks.

Roksandic and colleagues at the University of Winnipeg, alongside a team of international researchers, have named a new species that is an ancestor of modern humans (Homo sapiens), called Homo bodoensis. "It is generally considered that Homo erectus is the first human ancestor to have a global distribution after moving out of Africa in the Early Pleistocene. Towards the end of the Early Pleistocene, Homo develops a bigger brain. This brainy hominin gives rise to three different regional groups that we recognize as Neanderthals in Europe, their contemporaries in Asia and the Middle Pleistocene ancestor of Homo sapiens in Africa," Roksandic said.

Development of the human brain

The Middle Pleistocene, now referred to as the Chibanian age, is a particularly interesting period of human evolution, as it's when our most unique trait – a big brain – developed. However, researchers have faced several challenges when trying to study it, Roksandic explained: "We have far more fossils from the later periods, and there are bigger gaps in geographic coverage of the fossils from the Chibanian." She added, "Talking about human evolution during this time period became impossible due to the lack of proper terminology that acknowledges human geographic variation."

Previously, fossils obtained across Africa and Eurasia that date back to the Chibanian age have been assigned to either Homo heidelbergensis or Homo rhodesiensis. However, advances in ancient DNA sequencing suggest that some of these ancestors were early Neanderthals, and thus had been incorrectly named.

Enter: Homo bodoensis

Upon reassessing the fossils, Roksandic and colleagues decided to name the ancestor of Homo sapiens that lived in Africa during the Chibanian age Homo bodoensis. "Our team has provided a new name for the species that has been known for a long time. We have conceptualized it as an African Middle Pleistocene [Chibanian] species, ancestral to modern humans. It shows a suit of traits similar to earlier forms, and a suit of traits shared with other Middle Pleistocene humans [Chibanian] and a unique form of browridges," Roksandic explained. The name stems from a skull that was discovered in Bodo D'ar, Ethiopia. In addition to these African fossils, the name will also be assigned to Chibanian humans that occupied some areas of Southeast Europe, however many specimens from Southeast Europe will now be reclassified as Neanderthals.

"We believe that this name fills a need in our ability to communicate about movement and interactions of these different hominin groups. If it gets taken by our colleagues, it will have an impact on how we talk about this important period," Roksandic concluded.

Mirjana Roksandic was speaking to Molly Campbell, Science Writer for Technology Networks.

Reference: Roksandic M, Radović P, Wu X-J, Bae, CJ. Resolving the “muddle in the middle”: The case for Homo bodoensis. Evol Anthoropol. 2021. doi: 10.1002/EVAN.21929.