- After reassessing the human fossil record, some experts have identified a new type of human ancestor.
- This ancestor, Homo bodoensis, lived in Africa around 600,000 years ago and gave birth to modern man.
- One study suggests that Homo bodoensis shared a common ancestor with Neanderthals and Denisovans.
The genealogical tree of humanity has just been given a facelift.
After reassessing a set of controversial fossils that have been found on three continents but date from the same period, a group of anthropologists proposed the designation of a new species of human ancestor – and the elimination of two more.
Previously, these fossils – mostly discovered between 1908 and the late 1970s in Europe, Africa and Asia – were all considered to be part of the same ancestor group, called Homo heidelbergensis. But the new recommendation, described in a study published Thursday, suggests that lumping these human ancestors together in the same category is inaccurate.
Instead, say the authors, many fossils in Europe are Neanderthals, those in East Asia belong to another unknown and still unnamed group. Those from Africa, they suggest, should be called Homo bodoensis, a new name that comes from a 600,000-year-old skull discovered in Bodo D’ar, Ethiopia 35 years ago. Homo bodoensis would therefore be considered the direct ancestor of modern man – us – said the authors of the study.
Therefore, they suggested removing the name Homo heidelbergensis and also getting rid of a species called Homo rhodesiensis, also categorizing these fossils instead as bodoensis.
The move helps improve our understanding of how and when our own species of Homo sapiens evolved.
Classifying the species of human ancestors is tricky
The group of fossils that led researchers to suggest that this new category of human ancestors dates back to the Middle Pleistocene era, between 774,000 and 129,000 years ago. Genetic evidence suggests that at this time (and other eras) many human ancestors coexisted and crossed paths across Africa, Asia, and Europe.
Anthropologists recognize that in total nearly a dozen early human species existed 2.4 million years ago and the advent of modern man 300,000 years ago. Each is differentiated by when they lived, where they flourished, and what their bodies and brains looked like.
“Species, in our case, is a linguistic thing, not a biological thing,” Mirjana Roksandic, an anthropologist at the University of Winnipeg who co-authored the new study, told Insider.
In other words, the concept of “species” in human evolution does not indicate that a group cannot reproduce with other groups, as it suggests with animals. Instead, Roksandic said, the designations simply help anthropologists separate groups of ancestors with similar characteristics or geographic areas.
Even so, the process becomes tricky. Two years ago, a group of anthropologists at the annual meeting of the American Association for Biological Anthropology debated the definition of the species Homo heidelbergensis. They couldn’t agree on its precise identifying characteristics – and therefore on the fossils on file belonged to the group.
“Everyone had conflicting definitions,” Roksandic said.
The existence of Heidelbergensis was discovered thanks to a jawbone found in 1908 in the German city from which the species was named. Then 60 years later, anthropologists in France found a skull with a corresponding mandible. This, in turn, was related to the skull of Bodo from Ethiopia. Some fossils from eastern China were later named as part of this species as well.
But this geographic distribution was confusing, as was the fact that heidelbergensis fossils varied wildly in brain size and jaw shape.
This variation, according to Roksandic, indicates that heidelbergensis should not be a species at all.
He was “essentially a primitive Neanderthal,” she said, which is why her group suggests reclassifying all specimens of heidelbergensis found in Europe as such, and giving Africans the new name of Homo bodoensis.
Bodoensis skulls are marked by large brains similar in size to Neanderthals and Denisovans, Roksandic said, because all three species “inherited it from a common ancestor.”
This ancestor has not yet been discovered, but he is likely descended from Homo erectus, the first primitive man in Africa to walk upright, around 1.1 million years ago. About 200,000 years later, this ancestor split into two groups. One migrated to Europe and Asia, where it then branched off into Neanderthals and Denisovans in those respective places. The other group stayed in Africa and evolved into bodoensis, suggests the new study, which later gave birth to our species.
A legacy of colonialism
The second ancestor that Roksandic’s group wants to remove from the family tree, Homo rhodesiensis, was found in what is now Zimbabwe.
At the time of its discovery, the ancestor was named after Rhodesia, an unrecognized territory chartered by Cecil Rhodes and the British South Africa Company in 1965. Anthropologists have since classified fossils found in the area since the Middle Pleistocene as rhodesiensis (including the skull shown at left).
But the name, according to Roksandic and his co-authors, “is associated with a socio-political baggage from which our scientific community tries to dissociate itself”.
Rhodes, a British imperialist and business tycoon, forcibly seized land belonging to indigenous peoples to extract minerals. The link between this colonialism and the Homo rhodesiensis classification means that the name is rarely used, Roksandic added.
His team therefore suggested renaming all fossils from Rhodesiensis to bodoensis.
But Christopher Stringer, an anthropologist at the Natural History Museum in London, doesn’t think the names heidelbergensis and rhodesiensis should be discounted. He told New Scientist that the name rhodesiensis refers to the territory, not Rhodes itself. Plus, Stringer added, if the names are to go, other anthropologists have already suggested good options.
“Even if you got rid of rhodesiensis, other names would apply rather than creating a new one,” Stringer said.
For example, in the 1950s, Scottish anthropologist Matthew Drennan suggested the name Homo saldanensis for a skull discovered in South Africa, although this fossil was later classified as heidelbergensis.
Roksandic’s team say the skull should also be referred to as bodoensis.