Homo antecessor
Homo antecessor | |
---|---|
The "Boy of Gran Dolina" fossils ATD6-15 (frontal bone) ATD6-69 (maxilla) Museo Arqueológico Nacional, Madrid | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Primates |
Suborder: | Haplorhini |
Infraorder: | Simiiformes |
Family: | Hominidae |
Subfamily: | Homininae |
Tribe: | Hominini |
Genus: | Homo |
Species: | †H. antecessor
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Binomial name | |
†Homo antecessor Bermúdez de Castro et al., 1997
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Homo antecessor (
Despite being so ancient, the face is unexpectedly similar to that of modern humans rather than other archaic humans—namely in its overall flatness as well as the curving of the cheekbone as it merges into the upper jaw—although these elements are known only from a juvenile specimen. Brain volume could have been 1,000 cc (61 cu in) or more, but no intact braincase has been discovered. For comparison, present-day modern humans average 1,270 cm3 for males and 1,130 cm3 for females. Stature estimates range from 162.3–186.8 cm (5 ft 4 in – 6 ft 2 in). H. antecessor may have been broad-chested and rather heavy, much like Neanderthals, although the limbs were proportionally long, a trait more frequent in tropical populations. The kneecaps are thin and have poorly developed tendon attachments. The feet indicate H. antecessor walked differently compared to modern humans.
H. antecessor was predominantly manufacturing simple pebble and
Taxonomy
million years ago ) |
Research history
The
The 25 m (82 ft) of
In 2007 a mandibular fragment with some teeth, ATE9-1, provisionally assigned to H. antecessor by Carbonell, was recovered from the nearby Sima del Elefante ("elephant pit") in unit TE9 ("trinchera elefante"), belonging to a 20–25-year-old individual. The site additionally yielded stone
The stone tool assemblage at the Gran Dolina is broadly similar to several other contemporary ones across Western Europe, which may represent the work of the same species, although this is unconfirmable because many of these sites have not produced human fossils.[2] In 2014 fifty footprints dating to between 1.2 million and 800,000 years ago were discovered in Happisburgh, England, which could potentially be attributed to an H. antecessor group given it is the only human species identified during that time in Western Europe.[8]
Classification
The face of H. antecessor is unexpectedly similar to that of modern humans compared to other archaic groups, so in their original description, Castro and colleagues classified it as the last common ancestor of modern humans and Neanderthals, supplanting H. heidelbergensis in this capacity.[2][5][1] The facial anatomy came under close scrutiny in subsequent years.[1]
In 2001 French
In 2007 primatologist Esteban Sarmiento and colleagues questioned the legitimacy of H. antecessor as a separate species because much of the skull anatomy is unknown; H. heidelbergensis is known from roughly the same time and region; and because the type specimen was a child (the supposedly characteristic features could have disappeared with maturity.) Such restructuring of the face, they argued, can also be caused by regional climatic adaptation rather than speciation.[14] In 2009 American palaeoanthropologist Richard Klein stated he was skeptical that H. antecessor was ancestral to H. heidelbergensis, interpreting H. antecessor as "an offshoot of H. ergaster [from Africa] that disappeared after a failed attempt to colonize southern Europe".[15] Similarly, in 2012, British physical anthropologist Chris Stringer considered H. antecessor and H. heidelbergensis to be two different lineages rather than them having an ancestor/descendant relationship.[9] In 2013, anthropologist Sarah Freidline and colleagues suggested the modern humanlike face evolved independently several times among Homo.[16] In 2017 Castro and colleagues conceded that H. antecessor may or may not be a modern human ancestor, although if it was not then it probably split quite shortly before the modern human/Neanderthal split.[17] In 2020 Dutch molecular palaeoanthropologist Frido Welker and colleagues concluded H. antecessor is not a modern human ancestor by analysing ancient proteins collected from the tooth ATD6-92.[18]
Age and taphonomy
The 2003 to 2007 excavations revealed a much more intricate
Human occupation seems to have occurred in waves corresponding to timespans featuring a warm, humid savannah habitat (although riversides likely supported woodlands). These conditions were only present during transitions from cool glacial to warm interglacial periods, after the climate warmed and before the forests could expand to dominate the landscape.[20] The dating attempts of H. antecessor remains are:
- In 1999 two ungulate teeth from TD6 were dated using uranium–thorium dating to 794 to 668 thousand years ago, and further constrained palaeomagnetically to before 780,000 years ago.[21]
- In 2008 TE9 of the Sima del Elefante was constrained to 1.2–1.1 million years ago using palaeomagnetism and cosmogenic dating.[6]
- In 2013 TD6 was dated to about 930 to 780 thousand years ago using palaeomagnetism, in addition to uranium–thorium and electron spin resonance dating (ESR) on more teeth.[22]
- In 2018 ESR dating of the H. antecessor specimen ATD6-92 resulted in an age of 949 to 624 thousand years ago, further constrained palaeomagnetically to before 772,000 years ago.[23]
- In 2022 ESR and single grain thermally transferred optically stimulated luminescence (SG TT-OSL) dated the opening of the Gran Dolina to roughly 900,000 years ago, and the sediments from TD4 to TD6 to between 890,000 to 770,000 years ago. These three units were probably deposited within a period of less than 100,000 years.[24]
Until 2013 with the discovery of the 1.4 million-year-old infant tooth from Barranco León, Orce, Spain, these were the oldest human fossils known from Europe,[25] although human activity on the continent stretches back as early as 1.6 million years ago in Eastern Europe and Spain indicated by stone tools.[26]
Anatomy
Skull
The facial anatomy of H. antecessor is predominantly known from the 10–11.5-year-old H. antecessor child ATD6-69, as the few other facial specimens are fragmentary. ATD6-69 is strikingly similar to modern humans (as well as East Asian
The upper
The
Torso
The notably large adult
Two atlases (the first neck vertebra) are known, which is exceptional as this bone is rarely discovered for archaic humans. They are indistinguishable from those of modern humans. For the axis (the second neck vertebra), the angle of the spinous process (jutting out from the vertebra) is about 19°, comparable with Neanderthals and modern humans, diverging from H. ergaster with a low angle of about 8°. The vertebral foramen (that houses the spinal cord) is on the narrow side compared to modern humans. The spine as a whole otherwise aligns with modern humans.[5]
There is one known (and incomplete) clavicle, ATD6-50, which is thick compared to those of modern humans. This may indicate H. antecessor had long and flattish (platycleidic) clavicles like other archaic humans. This would point to a broad chest. The proximal curvature (twisting of the bone on the side nearest the neck) in front view is on par with that of Neanderthals, but the distal curvature (on the shoulder side) is much more pronounced. The sternum is narrow. The acromion (that extends over the shoulder joint) is small compared to those of modern humans.[5] The shoulder blade is similar to all Homo with a typical human body plan, indicating H. antecessor was not as skilled a climber as non-human apes or pre-erectus species, but was capable of efficiently launching projectiles such as stones or spears.[30]
Limbs
The incomplete radius, ATD6-43, was estimated to have measured 257 mm (10.1 in). It is oddly long and straight for someone from so far north, reminiscent of the proportions seen in
Like those of other archaic humans, the
The
Growth rate
In 2010 Castro and colleagues estimated that ATD6-112, represented by a permanent upper and lower first molar, died between 5.3 and 6.6 years of age based on the tooth formation rates in chimpanzees (lower estimate) and modern humans (upper). The molars are hardly worn at all, which means the individual died soon after the tooth erupted, and that first molar eruption occurred at roughly this age. The age is within the range of variation of modern humans, and this developmental landmark can debatably be correlated with life history. If the relation is true, H. antecessor had a prolonged childhood, a characteristic of modern humans in which significant cognitive development takes place.[31]
Pathology
The partial face ATD6-69 has an ectopic M3 (upper left third molar), where it erupted improperly, and this caused the
The mandible ATE9-1 exhibits severe dental
The left knee bone ATD6-56 has a 4.7 mm × 15 mm (0.19 in × 0.59 in) height x breadth
The right
Culture
Technology
H. antecessor was producing simple stone tools at Gran Dolina. This
TD6.3
In the lower part of TD6.3 (TD6 subunit 3), 84 stone tools were recovered, predominantly small, unmodified quartzite pebbles with percussive damage—probably inflicted from pounding items such as bone—as opposed to manufacturing more specialised implements.[19]
Although 41% of the section's assemblage consists of flakes, they are rather crude and large—averaging 38 mm × 30 mm × 11 mm (1.50 in × 1.18 in × 0.43 in)—either resulting from rudimentary knapping (stoneworking) skills or difficulty working such poor quality materials. They made use of the unipolar longitudinal method, flaking off only one side of a core, probably to compensate for the lack of preplanning, opting to knap irregularly shaped and thus poorer quality pebbles.[19]
TD6.2
Most of the stone tools resided in the lower (older) half of TD6.2, with 831 stone tools. The knappers made use of a much more diverse array of materials (although most commonly chert), which indicates they were moving farther out in search of better raw materials. The Sierra de Atapuerca features an abundance and diversity of mineral outcroppings suitable for stone tool manufacturing, in addition to chert and quartz namely quartzite, sandstone, and limestone, which could all be collected within only 3 km (1.9 mi) of the Gran Dolina.[19]
They produced far fewer pebbles and spent more time knapping off flakes, but they were not particularly economic with their materials, and about half of the cores could have produced more flakes. They additionally modified irregular blanks into more workable shapes before flaking off pieces. This preplanning allowed them to use other techniques: the centripetal method (flaking off only the edges of the core) and the bipolar method (laying the core on an anvil and slamming it with a hammerstone). There are 62 flakes measuring below 20 mm (0.79 in) in height, and 28 above 60 mm (2.4 in). There are three conspicuously higher quality flakes, thinner and longer than the others, which may have been produced by the same person. There are also retouched tools: notches, spines, denticulates, points, scrapers, and a single chopper. These small retouched tools are rare in the European Early Pleistocene.[19]
TD6.1
TD6.1 yielded 124 stone tools, but they are badly preserved as the area was also used by hyenas as a latrine, the urine corroding the area. The layer lacks pebbles and cores, and 44 of the stone tools are indeterminate. Flakes are much smaller with an average of 28 mm × 27 mm × 11 mm (1.10 in × 1.06 in × 0.43 in), with ten measuring below 20 mm (0.79 in), and only three exceeding 60 mm (2.4 in).[19]
They seem to have been using the same methods as the people who manufactured the TD6.2 tools. They were only retouching larger flakes, the fourteen such tools averaging 35 mm × 26 mm × 14 mm (1.38 in × 1.02 in × 0.55 in): one marginally retouched flake, one notch, three spines, seven denticulate sidescrapers, and one denticulate point.[19]
Fire and palaeoclimate
Only a few charcoal particles have been collected from TD6, which probably originated from a fire well outside the cave. There is no evidence of any fire use or burnt bones (cooking) in the occupation sequences of the Gran Dolina. In other parts of the world, reliable evidence of fire usage does not surface in the archaeological record until roughly 400,000 years ago.[37] In 2016, small mammal bones burned in fires exceeding 600 °C (1,112 °F) were identified from 780- to 980-thousand-year-old deposits at Cueva Negra in southern Spain, which potentially could have come from a human source as such a high temperature is usually (though not always) recorded in campfires as opposed to natural bushfires.[38]
Instead of using fire, these early Europeans probably physiologically withstood the cold, such as by eating a high protein diet to support a heightened metabolism.
H. antecessor probably migrated from the
Food
The fossils of sixteen animal species were recovered
The Sima del Elefante site records the fallow deer, the bush-antlered deer, rhinos, E. stenonis, C. mosbachensis, U. dolinensis, the extinct big cat Panthera gombaszoegensis, the extinct lynx Lynx issiodorensis, the extinct fox Vulpes alopecoides, several rats, shrews, and rabbits, and undetermined species of macaques, boar, bison, and beaver. The large mammals are most commonly represented by long bones, a few of which are cracked open, presumably to access the bone marrow. Some others bear evidence of percussion and defleshing.[6] They were also butchering Hermann's tortoise, an easily obtainable source of meat considering how slowly tortoises move.[40]
The cool and humid
There is no evidence H. antecessor could wield fire and cook, and similarly the wearing on the molars indicates the more frequent consumption of grittier and more mechanically challenging foods than later European species, such as raw rather than cooked meat and underground storage organs.[42]
Territory and spatial organization
The archaeo-palaeontological records in
Cannibalism
Eighty young adult and child H. antecessor specimens from the Gran Dolina exhibit cut marks and fracturing indicative of cannibalism,[5][39] and H. antecessor is the second-most common species bearing evidence of butchering.[39] Human bodies were efficiently utilised, and may be the reason why most bones are smashed or otherwise badly damaged. There are no complete skulls, elements from the face and back of the skull are usually percussed, and the muscle attachments on the face and the base of the skull were cut off. The intense modification of the face was probably to access the brain. The crown of the head was probably struck, resulting in the impact scars on the teeth at the gum line. Several skull fragments exhibit peeling.[4]
The ribs also bear cut marks along the muscle attachments consistent with defleshing, and ATD6-39 has cuts along the length of the rib, which may be related to disembowelment. The nape muscles were sliced off, and the head and neck were probably detached from the body. The vertebrae were often cut, peeled, and percussed. The muscles on all of the clavicles were sawed off to disconnect the shoulder. One radius, ATD6-43, was cut up and peeled. The femur was shattered, probably to extract the bone marrow. The hands and feet variably exhibit percussion, cutting, or peeling, likely a result of dismemberment.[4]
In sum, mainly the meatier areas were prepared, and the rest discarded. This suggests they were butchering humans for nutritional purposes, but the face generally exhibits significantly more cutmarks than the faces of animals. When this is seen in prehistoric modern human specimens, it is typically interpreted as evidence of exocannibalism, a form of ritual cannibalism where one eats someone from beyond their social group, such as an enemy from a neighbouring tribe. But, when overviewing the evidence of H. antecessor cannibalism in 1999, Spanish palaeontologist Yolanda Fernandez-Jalvo and colleagues instead ascribed the relative abundance of facial cut marks in the H. antecessor sample to the strongly contrasting structure of the muscle attachments between humans and typical animal prey items (that is, defleshing the human face simply required more cuts, or the butcherers were less familiar with defleshing humans).[4]
Nonetheless, the assemblage had a lack of older individuals, composed entirely of young adults and juveniles. In 2010 Carbonell hypothesised that they were practising exocannibalism and hunting down neighbouring tribesmen.[46] In 2019, Spanish palaeoanthropologist Jesús Rodríguez and colleagues argued that — considering the high youth mortality rates in modern hunter-gatherer groups – the demographic is better explained as consuming fellow tribesmen (already dead from natural causes, war, or an accident), possibly simply to avoid wasting food.[47]
See also
Notes
- ^ The Tighennif remains were classified by French vertebrate paleontologist Camille Arambourg as Atlantanthropus mauritanicus in 1955.[10] This name is usually sunk into H. erectus, but many authors choose to distinguish Asian and African populations on a species level, with the latter classified into H. ergaster which was named in 1975. This is somewhat problematic as several African specimens sunk into H. ergaster were already given unique species designations which should take priority, including H. mauritanicus.[11]
- ^ The frontal breadth (the length of the frontal bone) and the bistephanic breadth (the length between each stephanion) of ATD6-15 are respectively 95–100 mm (3.7–3.9 in) and 100 mm (3.9 in), which are substantially longer than what is measured in the H. erectus specimens KNM ER 3733, KNM ER 3883, Sangiran 2, or Trinil 2, which each have an estimated brain volume of less than 1,000 cc (61 cu in).[2]
References
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Further reading
- de Castro, J.-M. B. (2002). El chico de la Gran Dolina [The Gran Dolina boy] (in Spanish). Crítica. ISBN 978-84-8432-317-4.