HUMAN EVOLUTION: Home bodoensis Taxonomy Muddle Middle

Will the newly named Homo bodoensis assist in resolving the "Muddle in the Middle" of human evolution?

If you're familiar with human evolution, you've probably come across something called the "muddle in the middle" by paleoanthropologists. If you're not familiar with the muddle, it refers to an era in the Middle Pleistocene when man's evolution was poorly known.

Between 774,000 and 129,000 years ago, the Middle Pleistocene/Chibanian saw the rise of our own species (Homo sapiens) in Africa and our closest cousins, the Neanderthals (Homo neanderthalensis) in Europe.

The researchers Mirjana Roksandic, Predrag Radovi, and their team from the University of Winnipeg decided to take matters into their own hands and create a new taxon dubbed Homo bodoensis in the hopes of addressing the current foggy state of Chibanian hominin taxonomy.

Our taxonomy has a flaw

Homo heidelbergensis and Homo rhodesiensis are the two most common human species found in Africa and Eurasia throughout the Chibanian epoch.

H. heidelbergensis was named after a jawbone discovered in a gravel pit in early twentieth-century Germany. Since then, all fossils that didn't fit into the categories of Neanderthals, modern humans, or our ancestor Homo erectus have been labeled H. heidelbergensis. The name is now sometimes used to refer to Middle Pleistocene hominins and other times to refer to numerous specimens discovered in Europe. Furthermore, newer DNA evidence suggests that some European H. heidelbergensis fossils were from early Neanderthals. As a result, the scientists concluded that in those instances, the term was redundant.

Mining activity led to the discovery of H. rhodesiensis in Zambia in the 1920s. The phrase can refer to any Late Pleistocene human lineage, however it is most commonly used to allude to a shared ancestor of Homo sapiens and Neanderthals. However, the name's controversies stem from its association with the horrors done by English imperialist Cecil Rhodes under British colonial authority, and the phrase is now rarely used.

The researchers quickly realized that both of these names had to go.

Getting to the bottom of the taxonomy conundrum

Sometimes the only way to solve a difficult situation is to start again from scratch.

The Middle Pleistocene could no longer be dismissed as the "muddle in the middle," as it is increasingly being recognized as a critical period that saw the global appearance of two key traits of later human morphology: greater encephalization and smaller teeth, as well as likely geographic group differentiation.

As a result, scientists decided to exclude two hominin taxa (H. heidelbergensis and H. rhodesiensis) and replace them with a new hominid species.

The researchers have proposed the creation of a new species, H. bodoensis, named after a 600,000-year-old skull discovered in 1976 in Bodo D'ar, Habasha (Ethiopia), to help clarify things. Many fossils previously identified as H. heidelbergensis or H. rhodesiensis would have to be reclassified to fit into this new name.

Homo bodoensis sp. nov. holotype partial cranium Bodo 1 (Middle Awash, Ethiopia). Frontal (a), left lateral (b), superior (c) inferior (d) views. Scale bar: 5 cm.

According to Siberian and Tibetan fossils, Homo bodoensis was the direct ancestor of Homo sapiens, forming a separate branches of the human family tree from the one that gave rise to the Neanderthals and the mysterious Denisovans, who lived around the same time as their Neanderthal cousins.

Roksandic is convinced that "The International Commission on Zoological Nomenclature allows name modifications only under very rigorous conditions, therefore naming a new species is a significant matter. We are optimistic that this one will last a long time; a new taxon name will only live if it is used by other researchers."

Apart from proposing the creation of a new taxon, Homo bodoensis sp. nov., as an early Middle Pleistocene ancestor of the Homo sapiens lineage with a pan-African distribution that extends into the eastern Mediterranean, the researchers also propose the reassignment of many fossils from Western Europe to Homo neanderthalens to reflect the region's early appearance of Neanderthal derived traits in the Their findings also point to the possibility that Middle Pleistocene Asian fossils, notably those from China, belong to a separate lineage.