An artist's impression of Homo bodoensis

Homo bodoensis has been proposed as a direct ancestor of our species, Homo sapiens. Image © Ettore Mazza.

Read later

Beta

During Beta testing articles may only be saved for seven days.

Potential new human species may redraw the family tree

A new ancestor of modern humans with the potential to rip up the family tree has been tentatively named.

Homo bodoensis would have lived in what is now Ethiopia over 600,000 years ago, with researchers suggesting it replace two other hominid species that have been known to science for over a century. 

A new ancestor of Homo sapiens has been named by scientists as part of an effort to clean up our ancestry.

Homo bodoensis is named for a skull discovered in Bodo D'Ar, Ethiopia in the 1970s, and is thought to date back to the Chibanian Age 600,000 years ago. A new paper proposes this is a new hominid species that is a direct ancestor of Homo sapiens, replacing two other species that the authors consider to be poorly defined.

Lead author Dr Mirjana Roksandic says that naming a new human ancestor is a 'big deal' but is necessary to provide clarity in this period of history.

'Talking about human evolution during the Chibanian became impossible due to the lack of proper terminology that acknowledges human geographic variation,' she says.

However, Professor Chris Stringer, the Research Leader in human evolution at the Museum and who was not involved in the study, believes that the paper may not end the issues it aims to solve.

'Regarding Homo bodoensis as the Chibanian ancestor of the Homo sapiens lineage has its problems,' he says, 'as my and other research suggests that the facial shape of the Bodo skull is derived away from the ancestor of Homo sapiens, which was probably more like that of another relative, Homo antecessor.

'One of the authors of this paper has also just published another paper suggesting that a fossil from Hualongdong in China is also a Chibanian ancestor for Homo sapiens, which may well add further to the muddle!'

The research, led by an international team of scientists, was published in Evolutionary Anthropology.

A scene of two Homo bodoensis in a field with ancient animals

Homo bodoensis would have lived hundreds of thousands of years ago. Image © Ettore Mazza.

Hidden humans

The history of humanity is a complex one, beginning when our ancestors diverged from chimpanzees around five million years ago. From that point on, however, the path of evolution heads in a variety of different directions.

Early hominids gave way to the australopithecines, a group in which some of our most notable features began to emerge. Australopithecines are a group of species which had small brains and bodies, but were able to walk upright. The most well-known of the group is three-million-year-old specimen of a female Australopithecus afarensis, better known as Lucy.

While there is still debate, many scientists believe that an australopithecine subsequently gave rise to the first humans of our genus, Homo. Homo erectus is found from around two million years ago and is more recognisably like us, with similar body proportions. It is also believed to have made tools and may perhaps have even cooked.

Homo erectus would last for around 1.5 million years, but also gave rise to other species of hominid. These include Homo antecessor, which is commonly agreed to have branched off before Homo sapiens and Homo neanderthalensis split, but the rest of the period is the subject of intense debate.

In particular, the time of the Chibanian between 774,000 and 129,000 years ago is dubbed 'The Muddle in the Middle' by some researchers of human evolution as it is unclear when Homo sapiens first emerged within it.

The skull used to describe Homo rhodesiensis from the front and side

Homo rhodesiensis would no longer be considered a species if Homo bodoensis is accepted widely. Image © The Trustees of the Natural History Museum, London

A chip off the old block?

Two species believed to have evolved in this period are Homo heidelbergensis and Homo rhodesiensis. These species are sometimes believed to be direct ancestors of Homo sapiens, and sometimes as branches on the family tree.

This uncertainty is in part due to the description of Homo heidelbergensis based on a single jawbone known as the Mauer mandible. While some scientists believe that enough features of the bone set it apart from other hominids, the researchers in this study have suggested it may not be a species in its own right and is perhaps an early Neanderthal.

'I certainly agree with these authors that heidelbergensis has been used as a rag-bag term for too long, and I'm partly to blame for originating its wider usage in the 1980s,' Chris says.

'The species name does need rethinking as a wider term because the Mauer mandible is so idiosyncratic, but under naming rules you can't just cancel a species name you don't like.

'There have to be pretty good reasons, and the distinctiveness of Mauer probably warrants keeping that name for it and possibly similar fossils such as the Mala Balanica mandible.'

The researchers have also proposed that Homo rhodesiensis has been used for a range of different specimens from different species and should no longer be used. They also argue that the name is a legacy of colonialism, being named after the colony of Rhodesia and hence the controversial imperialist Cecil Rhodes.

In their place, the researchers propose that a new species of hominid, Homo bodoensis, should be described based on the Bodo skull.

The skull has an enlarged cranium compared to Homo erectus, but smaller than Homo sapiens, which suggests it is an intermediate species between them. However, it is not thought to be an ancestor of the Neanderthals, or another group known as the Denisovans, as the remains do not share similar features.

A number of other remains previously thought to be Homo heidelbergensis and Homo rhodesiensis are also reclassified as remains of the new species. Based on these remains, there are suggestions that Homo bodoensis may have reached the Eastern Mediterranean, with suggestions it may have dispersed deeper into Europe.

In any case, debate over our evolution is set to continue for the foreseeable future. The history of the hominids is by no means certain, but those backing its latest member believe it is here to stay.

'We are confident that Homo bodoensis will stick around for a long time,' Mirjana says, 'but a new taxon name will live only if other researchers use it.'