KeywordsCranial Capacity Human Fossil Comparative Anatomical Study Middle Awash Brow Ridge
Archaic Homo found in Europe, Africa, and possibly Asia between 70,000–200,000 years ago.
In 1907 a heavily built mandible, containing a complete set of teeth, was discovered by workers at a sandpit just outside of Heidelberg, Germany, in a village called Mauer. Initial observations of the jaw suggested similarities with Homo neanderthalensis, but the combination of a massive mandible and quite small teeth suggested something different. Paleontologist Otto Schoetensack gave a new species name to the fossil, Homo heidelbergensis (Heidelberg Man) (Schoetensack 1908). It has been a challenge to determine a precise geological date for this middle Pleistocene mandible considered to have lived sometime between 475,000 and 700,000 years ago.
Unfortunately, no cranial remains were found at Mauer, but a number of skulls from other sites in Europe, Africa, and, perhaps, China, dating to the same geological epoch as the Mauer mandible, are referred to H. heidelbergensis. The best preserved European specimens were found at Petralona, Greece, and Arago, France (Harvati 2007; Rightmire 1998).
Comparative anatomical study of skulls from Petralona and Arago led to the conclusion that the Mauer mandible would have been a good fit for these skulls, and therefore they should be placed in Homo heidelbergensis (Harvati et al. 2010). It has been difficult to geologically date the Petralona skull which was found in 1960 by shepherds in a cave close to Thessalonika, but associated animal bones provide an estimate of 350,000 years. The rugged male skull has a cranial capacity of 1220 cc and a massive supraorbital torus resembling other skulls (see below) that have been assigned to Homo heidelbergensis. Analysis of the anatomy of the Petralona specimen confirms a mosaic of primitive (Homo erectus like) and Neanderthal anatomy.
In 1971 a 400,000-year-old skull, Arago XXI, was excavated in the eastern Pyrenees in a limestone cave located near Tautavel, France. Initial impressions of the heavily built skull, presumably a male, with strong brow ridges and a low cranial capacity of 1166 cc suggested that it might belong to a primitive species well known in Asia called Homo erectus. More comprehensive analysis of Arago reveals many resemblances with the Petralona specimen and is now placed in Homo heidelbergensis. This decision is supported by the recovery of mandibles at Arago that resemble the Mauer mandible.
In Africa the most complete crania assigned to H. heidelbergensis come from Bodo, Ethiopia, and Kabwe, Zambia. The Zambian cranium, found by workers at the Broken Hill Mine in what was then called Rhodesia, is sometimes referred to as Rhodesian Man or the Broken Hill skull (Smith-Woodward 1921). Today it is known as the Kabwe skull. No stone tools were recovered, but associated parts of a pelvis and lower limb provide a glimpse into the postcranial skeleton, suggesting that Kabwe was a very tall and robustly built male.
The Kabwe skull has a cranial capacity of 1325 cc and was incredibly massive, sporting a prominent supraorbital torus at the front of the cranium. The majority of the dentition exhibits very heavy wear, with cavities and root abscesses that must have been painful. An undiagnosed lesion on the left wall of the cranium, above the ear canal, may also indicate disease.
Debate on Naming
Considerable debate has swirled around placement of all these specimens in a single species, Homo heidelbergensis, a taxon that was based on a single mandible. However, the European and African crania share many details of morphology and are collectively considered to be the kind of skull that would have had a Mauer-like mandible. Found in 1921 the cranium from Kabwe was given a separate species name, Homo rhodesiensis, leading some anthropologists to retain that name for the African material (Stringer 2012).
The Bodo skull was found in 1976 in Middle Awash Valley, Ethiopia (Conroy et al.1978). Hand axes and cleavers made on lava, of the Acheulean industry, were found nearby, and the associated faunal remains suggested a Middle Pleistocene age. The geological age of the Bodo specimen was confirmed with argon dating to be 600,000 years old.
The powerfully built Bodo skull with a very thick, projecting supraorbital torus possesses the largest face in the human fossil record and a cranial capacity of 1250 cc. Upon close examination, numerous cut marks were found on the cheeks, in the eye orbits, and on the frontal bone, indicating intentional defleshing of this individual (White 1986).
Sima de los Huesos
More than 5000 human fossils were excavated at Sima de los Huesos (“Pit of Bones”) located in the Atapuerca Mountains of northern Spain (Arsuaga et al. 2014). These bones come from the Middle Pleistocene epoch and have been dated to 400,000 before the present. Initially these fossils were placed in Homo heidelbergensis, because of anatomical similarity to other skulls placed in Homo heidelbergensis. Some anthropologists also drew attention to many anatomical resemblances of the Sima de los Huesos bones shared with Homo neanderthalensis. The amalgam of older Homo heidelbergensis anatomy with later, derived Neanderthal features has attracted widespread debate. Perhaps it is useful to view Neanderthals within the accretion model that posits the gradual accumulation of Neanderthal features over time. With the recovery of diagnostic Neanderthal DNA in Sima de los Huesos bones (Matthias et al. 2016), a plausible interpretation is that they represent an early stage in the Neanderthal lineage that led to later “Classic Neanderthals.”
It is now widely agreed that the great number of anatomical similarities shared by all Homo heidelbergensis fossils justifies their inclusion in a single species. In Europe, as a result of their isolation due to Pleistocene glaciations, they evolved into Neanderthals. The African fossil record for Homo heidelbergensis such as Bodo and Kabwe supports an African origin for modern humans who migrated into Europe and replaced the Neanderthals.
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