Homo antecessor

This species name is highly debated with many considering the remains to be Homo heidelbergensis. Whatever species they come from, these fossils are the oldest Homo found in western Europe.

Background to discovery

Age

This species lived about 800,000 to 1.2 million years ago in Europe.

Important fossil discoveries

These are the oldest human remains found in western and Central Europe.

Remains of over 80 fossils representing at least 6 individuals and including skeletal and cranial remains were found at Gran Dolina in Atapuerca, Spain, between 1994-1996. These remains date to at least 780,000 years old. Due to the unique combination of features, the discovers believed that they had found a new species. The name Homo antecessor was announced in 1997 by JL Arsuaga.

In 2007-2008 researchers working at Sima del Elefante, also in Atapuerca, recovered remains dating to about 1.2 million years ago. The human fossils included an isolated molar and a jaw bone with some front teeth (ATE9-1). The molar was described as belonging to an individual aged between 20 and 25 years and being ‘well worn’. Other remains included stone flakes and butchered animal bones.

The type specimen for this species is ATD 6-69 (Hominid 3). It is the cranium of a 10-year old juvenile found at Gran Dolina. Some experts claim that having a juvenile as a type specimen is a problem as some of the features may simply be juvenile traits that are lost in the adults of the species. However, a comparison to juveniles of other species shows these traits to be unique to these remains.

What the name means

The genus name Homo is the Latin word for ‘human’ whereas the species name antecessor is a Latin word meaning ‘explorer’, ‘pioneer’ or ‘early settler’. This name was assigned due to the belief that these people belonged to the first human population as yet known from the European continent.

Distribution

Remains have been found at two sites in Atapuerca, Spain - Gran Dolina (Level TD-6) and Sima del Elefante.

Position on the human family tree

This is a controversial species designation. Most researchers consider these to be part of an early and variable Homo heidelbergensis population. However, its discoverers suggest that it shares more traits with modern humans than does European H. heidelbergensis so consider H. antecessor to be the last common ancestor of Neanderthals and Homo sapiens. Some dental and cranial features suggest H. antecessor is descended from Homo ergaster.

The discovers offer this scenario for the evolutionary and temporal relationships of H. antecessor to other species. H. ergaster gave rise to H. antecessor in Africa. About one million years ago, H. antecessor spread via the Middle East to Europe, including Gran Dolina. In Europe, H. antecessor evolved into H. heidelbergensis, who were the ancestors of the Neandertals. In Africa, H. antecessor evolved into Homo sapiens via an unknown species, although possibly represented by such fossils as the Bodo and Kabwe skulls. In this scenario H. heidelbergensis is off the line leading to modern humans as it is the descendant of H. antecessor in Europe. African H. heidelbergensis would require a name change, probably to Homo rhodesiensis, the name originally given to the Kabwe skull.

Key physical features

This species has a unique combination of features in the cranium, teeth and lower jaw that are collectively different from other Homo fossils, rather than any particular feature that distinguish it from others. Features show a mix of modern and archaic traits.

Brain size

• approximately 1000 cc (compared to 1350cc for humans today)

Body size and shape

• similar to modern humans, but more robust
• males averaged about 1.6-1.8 metres tall

Skull:

• modern traits include a modern looking mid-face, canine fossa with ‘hollowed’ cheekbone and projecting nose
• archaic traits include a low forehead and marked double brow ridge, similar to Chinese Homo erectus and Neanderthals
• protruding occipital bun at the rear of the skull

Teeth and jaws

• primitive aspects of dentistry include robust teeth, premolars with multiple roots and shovel-shaped incisors in the upper jaw
• derived features include canines and some of the anterior teeth that are reduced in size
• tooth eruption patterns appear to be similar to modern humans, suggesting the same developmental rates
• receding chin
• mandible (lower jaw) is thinner than that of H. ergaster and H. habilis
• postcanine teeth are smaller than in H. habilis, within the range of H. ergaster, H. erectus and H. heidelbergensis

Lifestyle

Culture

Excavations at Gran Dolina also uncovered roughly 200 stone tools and about 300 animal bones from the same levels as the human remains, dated to at least 780,000 years old. Similar finds were made at Sima del Elefante, with about 32 stone tool pieces and a variety of mixed animal remains recovered, all dating to about 1.1-1.2 million years old.

Stone tools at both sites were simple Mode 1 technology or Oldowan-style and made from local raw materials. Tools included simple cutting flakes, lacking the more sophisticated tools found elsewhere at this time. At Sima del Elefante the cave seemed to be a tool knapping site, with flakes showing clear evidence of manufacturing techniques - artefacts were detached by direct hammer percussion on hand-held medium-sized cores. The absence of retouched tools at this site, along with the nature of the tool kit, suggests that the tools were created mainly for processing and eating meat and marrow.

Cut marks are present on the animal remains at both sites. The marks are consistent with processing by humans for the purpose of obtaining meat and marrow. Interestingly, at Gran Dolina most of the human material also display the same types of cut marks, indicating dismemberment was probably the goal. The lack of carnivore tooth marks supports the suggestion that it was humans that made the incisions or marks. Whether this was due to cannibalism is debatable as there are cases of defleshing bones that do not involve eating the flesh. However, these cases are usually relate to funerary rites of which there is no evidence for in this species (or any Homo species for at least another 700,000 years).

It does not appear that these people lived permanently in either of the caves. Rather, they visited them for certain activities or at certain times of the year. They were probably nomadic and followed food sources.

Environment and diet

Small animal remains at the Sima del Elefante site suggest the climate at the time was generally warm and humid with warmer-cooler shifts. This correlates with the Waalian, a warm stage also with wamer-cooler shifts that is dated to 1.5.to 1.3 million years ago.

This conditions are similar to those suggested for the region about 800,000 years ago. At this time, the climate was warm, wet and relatively stable. This all changes about 600,000 to 500,000 years ago, when conditions became relatively harsh and cold. It is not long after this that humans living in Europe start to develop Neanderthal-like features, many of which appear to be adaptations to very cold environments.

The diet appears to have included large amounts of meat. Many of the remains at both sites are of large mammals that have been butchered and some of the larger bones have been broken to obtain the marrow. At Gran Dolina, young horse and deer are particularly common. The remains do not indicate whether the animals were hunted or scavenged, but both methods of procuring food were probably used. It is also likely that they supplemented their diet with plants.

Futher reading:

M. Bermúdez de Castro, J. L. Arsuaga, E. Carbonell, A. Rosas, I. Martı́nez, M. Mosquera. ‘A Hominid from the Lower Pleistocene of Atapuerca, Spain: Possible Ancestor to Neandertals and Modern Humans’, Science, 30 May 1997, Vol. 276, pp1392