Homo heidelbergensis

Introduction:
Homo heidelbergensis, or “archaic Homo sapiens”, is the name given to the large-brained hominins that appeared in Africa 600,000 years ago and migrated into Europe and possibly Asia. It is conventionally regarded as having given rise to modern humans in Africa and the Neanderthals in Europe.

The type specimen is the Mauer Mandible (Mauer 1), a virtually-complete lower jaw recovered from fluvial beds near the village of Mauer, in south-west Germany. The find was made on 21 October 1907 by a gravel-pit worker named Daniel Hartmann and described the following year by Professor Otto Schoetensack of the University of Heidelberg. The Mauer Mandible has been dated to 500,000 years old.

Until about ten years ago, the rather unsatisfactory term “archaic Homo sapiens” was used to describe any mid-Pleistocene hominin that wasn’t Homo erectus, Homo sapiens, or a Neanderthal. The latter was usually classified as a subspecies of Homo sapiens, i.e. H. s. neanderthalensis, but they are now generally regarded as a separate species. Consequently “archaic Homo sapiens” is itself regarded as a separate species, with the 1907 name Homo heidelbergensis having seniority under the rules of taxonomy.

As Manzi (2004) notes however this is no more than a revision of the old paradigm, with the substitution of a grade “archaic Homo sapiens” with a clade, Homo heidelbergensis, accompanied by the recognition of three distinct species, i.e. H. heidelbergensis, H. neanderthalensis and H. sapiens, with corresponding speciation events between the Middle and Late Pleistocene in Africa and Eurasia.

Whether or not Homo heidelbergensis is a genuine species or simply a grade of “Version 3.0 human” containing several species remains controversial.

Key Fossils:
Kabwe (Broken Hill), Zambia: Skull and several postcranial bones including a femur and a tibia (Broken Hill 1). It was found in an iron and zinc mine in Broken Hill, Northern Rhodesia (now Kabwe, Zambia) in 1921 by a Swiss miner named Tom Zwiglaar. Dating is uncertain, but probably between 700,000 and 400,000 years old. It has a cranial capacity of around 1100cc and was originally described as Homo rhodesiensis.

Lake Ndutu, Tanzania: a 400,000 year old cranium, found in 1973, with an estimated cranial capacity of 1100cc.

Bodo, Middle Awash, Ethiopia: a 670,000-600,000 year old cranium found in 1976 by a survey headed by Jon Kalb. Cranial capacity is 1300cc.

Sima de los Huesos, Atapuerca, Spain: 350,000 year old remains representing 28 individuals, including three nearly complete skulls, SH4 (cranial capacity 1390cc), SH5 (cranial capacity 1125cc) and SH6 (cranial capacity 1220cc).

Petralona, northern Greece: Skull discovered in cave system in 1960, dated 250,000 – 150,000 years old, with a cranial capacity of 1200cc.

La Caune de Arago, Tautavel in southern France: isolated teeth, cranial, mandibular and fragmentary postcranial remains belonging to at least four adults and three children, dated to approximately 450,000 years old. The distorted Arago 21 cranium has an estimated capacity of 1150cc.

Mauer, Germany: the Mauer Mandible, as mentioned above.

Steinheim, Germany: a distorted but nearly complete cranium found in a gravel pit 1933 by Karl Sigrist. It is believed to be 350,000-250,000 years old. The cranial capacity is 1100cc.

Boxgrove, England: a partial tibia discovered in 1994 dated to 423,000-362,000 years old, associated with Acheulian tools.

Swanscombe, England: three skull fragments belonging to the same individual recovered between 1935 and 1955; believed to be 300,000-200,000 years old and popularly known as Swanscombe Man, though now thought to be female. The cranial capacity has been estimated at 1325cc.

Dali, Shaanxi Province, China: a 250,000 year old cranium discovered by Shuntang Liu in 1978, with a cranial capacity of 1120cc.

Jinniu Shan: cranium, vertebrae, ribs, pelvis, patella and limb bones discovered in 1984. The cranial capacity is 1300cc and the remains are believed to be 250,000 years old.

Description:
Manzi (2004) selects the Middle Pliocene fossils from Kabwe, Petralona and Dali fossils as being typical of Homo heidelbergensis. They have a “transitional aspect” between earlier and more recent hominins which include both primitive and derived traits. Primitive or “archaic” features include a heavily-built cranial structure with massive brow ridges; crests in the temporo-occipital region, including erectus-like occipital and angular tori; a low and antero-posteriorly elongated cranial vault; a protruding and large facial skeleton; and the absence of a modern chin. These traits are however reduced in comparison to Homo ergaster/erectus.

The main derived feature is that the general shape of the cranial vault is consistent with increased brain-size. The frontal is less receding than it is in earlier hominins; the parietal profile is more convex along the mid-sagittal plane and less angled in coronal sections; and the occipital squama is more vertical and arched.

The cranial capacity is typically between 1100-1300cc, around 90% of that of modern humans, a considerable increase on that of Homo erectus/ergaster.

Affinities to other hominins:
The view that this species evolved in Africa about 600,000 years ago, then migrated into Europe, and that the two lineages led to respectively Homo sapiens and the Neanderthals, is probably as convincing as any of the alternatives.

Homo antecessor (known only from Spain) has recently been touted as ancestral to Homo heidelbergensis, suggesting that either the latter was a European species that later migrated back into Africa, or that Homo antecessor evolved in Africa.

Another possibility is that African and European Homo heidelbergensis are different species, with the Bodo Cranium an early example of the former. On this view, the African species would take the name originally assigned to the Bodo Cranium, Homo rhodesiensis. However the sudden increase in brain size to 90% of the modern average seen in the fossil record at around 600,000 years ago, after remaining more or less static at 65% during the previous 1.2 million years, does suggest a punctuated event which in turn suggests a single species.

Just about all that can be safely said at the present time is that our understanding is very incomplete!

Technology:
Homo heidelbergensis is associated with the same Acheulian (Mode II) technology as that originated by Homo ergaster 1.65 million years ago; however later Acheulian hand-axes are thinner, more symmetric and more extensively trimmed. Some authorities describe this technology as “Late Acheulian”. It is possible that its appearance is connected with the emergence of Homo heidelbergensis and is a product of this species greater cognitive abilities.

References:

J. M. Bermudez de Castro, J. L. Arsuaga, E. Carbonell, A. Rosas, I. Martınez, M. Mosquera (1997): A Hominid from the Lower Pleistocene of Atapuerca, Spain: Possible Ancestor to Neandertals and Modern Humans, Science Vol. 276 30 May 1997.

Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.

Conroy G (1997): “Reconstructing Human Origins: A Modern Synthesis”, W.W. Norton & Co. Inc, New York, NY & London.

Klein, R. (1999): The Human Career (2nd Edition), University of Chicago Press.

Klein R & Edgar B (2002): “The Dawn of Human Culture”, John Wiley & Sons Inc., New York.

Lewin, R and Foley, R 2004: Principles of Human Evolution (2nd edition), Blackwell Science Ltd.

Manzi G (2004): Human Evolution at the Matuyama-Brunhes
Boundary, Evolutionary Anthropology 13:11–24 (2004).

Scarre C (2005) (Ed): “The human past”, Thames & Hudson.

Stringer C & Andrews P (2005): “The Complete World of Human Evolution”, Thames & Hudson.

© Christopher Seddon 2009

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Homo antecessor

Homo antecessor (“Pioneer Man”) is the name given to an extinct human species known from just two sites in the Atapuerca Hills of Northern Spain – Gran Dolina and Sima del Elefante. The remains were discovered by Eudald Carbonell, Juan Luis Arsuaga and J. M. Bermúdez de Castro.

The initial discoveries were made at the Gran Dolina Cave, Layer TD6 between 1994 and 1995. The find comprised over 90 bone fragments including 18 skull fragments, 4 partial jaws, 14 teeth, 16 vertebrae, 16 ribs, 20 bones from the hands and feet, 2 wrist bones, 3 collar bones, 2 lower arm bones, a thigh bone and 2 knee-caps from a minimum of 6 individuals, all of whom were aged between 3 and 18 when they died. Around 200 flaked stone artefacts were also found. Palaeomagnetic considerations date the find to at least 700,000 years old; electron spin resonance dates the fossils and artefacts to between 857,000 and 780,000 years old; bones of extinct rodent species support this age; the excavators conservatively date the find to 800,000 years old.

However in 2007 a fragment of a mandible and an isolated lower left fourth premolar from the same individual were recovered from the TE9 layer at the nearby Sima del Elefante site. These have also been assigned to Homo antecessor and dating based on palaeomagnetism, biostratigraphy and cosmogenic nuclides suggests an age of 1.2–1.1 million years.

The tools found at the Gran Dolina are simple Mode 1 (Oldowan) technology, with no evidence of Acheulian hand-axes or cleavers characteristic of later African Homo ergaster or H. heidelbergensis.

One of the most significant features of the Gran Dolina TD6 find is that around 25% of the bones show signs of human-caused damage including chop and cut marks, peeling where bones have been broken and bent, and percussion marks where bones have been splintered for marrow extraction. All of which adds up to a compelling case for cannibalism. The extent of the damage suggests this was of a dietary rather than ritual nature, suggesting in turn nutritional stress.

Bermúdez de Castro and his colleagues argue against the currently popular view that hominids such as Mauer, Vertesszollos, Bilzingsleben, Arago, and Petralona, together with Bodo, Broken Hill 1, and Dali (among other middle Pleistocene fossils not considered to be H. erectus) belong to a single species, Homo heidelbergensis, that was ancestral to both modern humans and the Neanderthals. They argue that European middle Pleistocene fossils are ancestral only to the Neanderthals and that the Mauer mandible, the holotype for Homo heidelbergensis, shows clear derived Neanderthal traits, such as a large retromolar space, whereas teeth shape and morphology are indistinguishable from those of Neanderthals. They conclude that other than a European chronospecies, H. heidelbergensis should be rejected.

Dental and cranial features suggest Homo antecessor is close to Homo ergaster. While Homo antecessor has similarities to Homo heidelbergensis (i.e. proto-Neanderthals), it has more traits in common with modern humans than does Homo heidelbergensis, being for example relatively gracile, most similar to H. ergaster and modern humans but unlike H. heidelbergensis or the Neanderthals. On this picture, Homo antecessor evolved from Homo ergaster in Africa then spread via the Middle East to Europe where it evolved (via Homo heidelbergensis) into the Neanderthals. In Africa Homo antecessor evolved into Homo sapiens via such fossils as the Bodo and Kabwe skulls. The species Homo rhodesiensis or Homo helmei would have to be revived for these presumptive H. antecessor/H. sapiens transitional types, with H. heidelbergensis being a solely European transitional type between H. antecessor and the Neanderthals.

Neither this view nor Homo antecessor as a species is widely accepted. Many believe that H. antecessor is an ofshoot of Homo ergaster and that it died off without issue, possibly during the glacial periods of 800,000-600,000 years ago. Clearly further evidence is needed, from Africa in particular.

References:

J. M. Bermudez de Castro, J. L. Arsuaga, E. Carbonell, A. Rosas, I. Martınez, M. Mosquera (1997): A Hominid from the Lower Pleistocene of Atapuerca, Spain: Possible Ancestor to Neandertals and Modern Humans, Science Vol. 276 30 May 1997.

Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.

Eudald Carbonell, Jose M. Bermudez de Castro, Josep M. Pares, Alfredo Perez-Gonzalez, Gloria Cuenca-Bescos, Andreu Olle, Marina Mosquera, Rosa Huguet, Jan van der Made, Antonio Rosas, Robert Sala, Josep Vallverdu, Nuria Garcıa, Darryl E. Granger, Marıa Martinon-Torres, Xose P. Rodrıguez, Greg M. Stock, Josep M. Verges, Ethel Allue, Francesc Burjachs, Isabel Caceres, Antoni Canals, Alfonso Benito, Carlos Dıez, Marina Lozano, Ana Mateos, Marta Navazo, Jesus Rodrıguez, Jordi Rosell & Juan L. Arsuaga (2008): The first hominin of Europe, Nature Vol 452 27 March 2008.

Scarre C (2005) (Ed): “The human past”, Thames & Hudson.

© Christopher Seddon 2008

The Herto remains (Homo sapiens idaltu)

The Herto remains are a find of early anatomically modern human remains from Herto, Middle Awash in the Afar Triangle, Ethiopia. The find comprises of three well-preserved crania plus fragmentary remains. The crania were discovered in 1997 by a team lead by Dr. Tim White but the find was not described until 2003. Two of the crania belong to adult males; the third belongs to a six-year-old child. The cranial capacity of the best-preserved adult cranium, known as BOU-VP-16/1, is 1450cc – at the high end of the modern human range.

Deposits dated by the argon-40/argon-39 method to 154,000 years old and 160,000 years old provided constraints on the age of the Herto remains. At the time, they were the earliest examples known of modern Homo sapiens. Crucially they pre-date the “classic” Neanderthals, ruling out the possibility that modern humans are descended from the latter.

Although the finds are close enough to present-day humans to be considered the same species, they retain some primitive morphological features from earlier human species such as Homo heidelbergensis. The braincases are longer and the brow ridges are more pronounced than those of later humans. For this reason, White erected a new subspecies for them, Homo sapiens idaltu (idaltu means elder or first-born in the Afar language).

Stone tools found with the fossils suggest a transitional phase between the Acheulian hand-axe and Middle Stone Age (MSA) flake technologies. Such assemblages are traditionally classified as final Acheulian.

The Herto people occupied the margin of a freshwater lake, and archaeological evidence indicates butchery of large mammal carcasses, particularly hippopotamus. Whether they hunted or simply scavenged these animals is not known.

The less-intact adult cranium (BOU-VP-16/2) bears cut-marks made with stone tools. Some of these are deep cut-marks typical of de-fleshing, but more abundant are more superficial marks showing a repetitive scraping motion, a pattern that is not seen on faunal remains processed for food, or in instances of cannibalism.

The child’s skull exhibits cut-marks made by a very sharp stone flake deep in its base. The rear part of the cranial base was broken away, and the broken edges polished. The sides of the skull show a deep polish that may have formed from repeated handling of the skull after it was de-fleshed.

All of this implies some form of ancient mortuary practice. Ethnographic evidence from several cultures documents the post-mortem manipulation and preservation of human remains as part of mortuary practices. For example, some New Guinean crania show cut-marks, decoration and polishing reminiscent of traces seen on the Herto people.

This suggests the Herto people may have had complex belief systems; a feature considered to be one of the hallmarks of modern human behaviour.

References:

Clark JD, Beyene Y, WoldeGabriel G, Hartk WK, Renne PR, Gilbert H, Defleurq A, Suwa G, Katoh S, Ludwig KR, Boisserie J-R, Asfawkk B & White TD (2003): Stratigraphic, chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash, Ethiopia, Nature Vol 423 12 June 2003.

White TD, Asfaw B, DeGusta D, Gilbert H, Richards GD, Suwa G & Howell FC (2003): Pleistocene Homo sapiens from Middle Awash, Ethiopia, Nature Vol 423 12 June 2003.

© Christopher Seddon 2008

Omo remains (Homo sapiens)

The Omo I (Kibish) and Omo II (Kibish) remains are currently the oldest-known fossils of anatomically-modern humans (Homo sapiens). They were recovered by Richard Leakey in 1967 from the base of Member I of the Kibish Formation near the Omo River in south-western Ethiopia. Both Omo I and Omo II comprise a braincase and some postcranial material. Omo I fully modern in appearance; Omo II is slightly more primitive with a long, low cranium. However both are believed to be about the same age.

Originally believed to be around 130,000 years old, the Omo remains have recently been assigned a date of 195,000 +/- 5,000 years old, based on argon-40/argon-39 dating of volcanic tuffs (ash) found within Member I at levels. This makes them substantially older than the Herto remains discovered in 1997, previously thought to be the earliest-known fossil remains of modern humans. What is curious is that the 156,000 year old Herto remains, despite being around 40,000 years more recent than the Omo remains, retain more primitive features and were originally assigned their own subspecies, Homo sapiens idaltu.

Reference:

McDougall I, Brown FH & Fleagle JG (2005): Stratigraphic placement and
age of modern humans from Kibish, Ethiopia, Nature 734 Vol 433 17 Feb 2005.

© Christopher Seddon 2008

The Florisbad skull (Homo helmei)

Florisbad 1 is a hominin fossil recovered by Prof. T.F. Dreyer from the depths of a warm lithium spring deposit in the Orange Free State, South Africa, in 1932. The skull consists of frontal and parietal pieces and an incomplete right side of the face (Conroy, 1997). In 1996 a direct date was obtained for the skull using electron spin resonance dating on two small samples of enamel removed from the only tooth to be found with the skull. These yielded a date of 259,000 +/- 35,000 years (Grun et al 1996).

The skull was originally classified as Homo helmei by Dreyer to mark its distinctiveness from other fossil Homo sapiens. It is now generally either described as “archaic Homo sapiens” or assigned to Homo heidelbergensis, but it may be an intermediate form between H. heidelbergensis and H. sapiens, in which case retention of the Homo helmei classification would be appropriate.

References:

Conroy G (1997): “Reconstructing Human Origins: A Modern Synthesis”, W.W. Norton & Co. Inc, New York, NY & London.

Grün, R., Brink, J.S., Spooner, N.A., Taylor, L., Stringer, C.B., Franciscus, R.B. & Murray, A. (1996): Direct dating of the Florisbad hominid. Nature 382: 500–501.

Lewin, R and Foley, R 2004: Principles of Human Evolution (2nd edition), Blackwell Science Ltd.

© Christopher Seddon 2008

The Kabwe skull (Homo rhodesiensis)

The Kabwe skull or Broken Hill 1 is a hominin fossil originally classified as Homo rhodesiensis. It was found in an iron and zinc mine in Broken Hill, Northern Rhodesia (now Kabwe, Zambia) in 1921 by a Swiss miner named Tom Zwiglaar. In addition to the skull, several postcranial bones were found including a femur and a tibia. The skull became known to anthropologists as Rhodesian Man but is now commonly referred to as the Broken Hill or Kabwe skull. The Kabwe skull is estimated to have a cranial capacity of 1,100cc. It has heavy brow ridges and a slightly keeled and constricted frontal bone.

The age of the remains are contentious, with secure dating impossible due to the destruction of geological context by mining activity. Archaic mammal species recovered with the skull suggest a date of 700,000-400,000 years old (Scarre, 2005). Conroy (1997) cites archaeological and palaeontological evidence that give a date of more than 125,000 years; Lewin & Foley (2004) give an age of “at least 200,000 years”.

The Kabwe skull was until recently classed as “archaic Homo sapiens” but is usually now classed as Homo heidelbergensis. Some authorities retain the H. rhodesiensis classification and reserve H. heidelbergensis for European hominins.

References:

Conroy G (1997): “Reconstructing Human Origins: A Modern Synthesis”, W.W. Norton & Co. Inc, New York, NY & London.

Lewin, R and Foley, R 2004: Principles of Human Evolution (2nd edition), Blackwell Science Ltd.

Scarre C (2005) (Ed): “The human past”, Thames & Hudson.

© Christopher Seddon 2008