Homo heidelbergensis

Homo heidelbergensis is an extinct species of the genus Homo, which arose more than 600,000 years ago and lasted until at least 200,000 years ago. years (Chibaniense, mid-Pleistocene).

They were tall individuals averaging 1.75 m in height with a weight of 62 kg for males, and 1.57 m with 51 kg for females. They had large skulls averaging 1,350 cm³, very flattened in relation to those of modern man, with protruding jaws and a large nasal opening. It is the first human species in which it is possible to detect signs of a symbolic mentality.

Its scientific name derives from the proximity of the city of Heidelberg (Germany) to the place where the first fossils were found, which underlines the fact that it is the first Homo to reach the steppes of central and northern Eurasia.

Its anatomy has been largely described by remains found at the Sima de los Huesos site in Atapuerca.

Origin and evolution

The origin of Homo heidelbergensis dates back to about 600,000 years ago in Africa, from where it spread to Europe, where, unlike previous hominids, it inhabited a wide geographic range, penetrating into the cold European steppes during the Middle Pleistocene glaciations. Regarding the exact origin of this species, there is a strong debate due to the morphological similarities (especially cranial) that H. heidelbergensis presents with Homo rhodesiensis.

Map showing the sites where remains of heidelbergensis and put them on.

On the one hand, various researchers argue that, based on the striking similarity between both species and the difficulty in finding differences between their remains, both should be recognized as a single species, H. heidelbergensis (as this was described 15 years before H. rhodesiensis). For their part, other researchers prefer to separate the African and European populations into different species based on some anatomical details. In any case, the origin of H. heidelbergensis is located in Africa, where after 800,000 years ago the increase in the frequency of glacial-interglacial cycles produced an increase in the aridity of the continent that led to the appearance of this new type of hominids.

Thus, two currents are established to explain the appearance of H. heidelbergensisː

• H. heidelbergensis It appears in Africa at the beginning of the Middle Pleistocene, from where it expands to the European continent, dividing into two populations that will give rise to Neanderthals and Denisovans, on the one hand (European population), and to modern man on the other (African population).

• H. rhodesiensis arises in Africa at the beginning of the Middle Pleistocene, from which it expands to the European continent, giving rise to a new species, H. heidelbergensiswhich will later evolve in Neanderthals and Denisovans; H. rhodesiensis give rise to Homo sapiens about 130,000 years ago in Africa.

Another, more controversial explanation establishes Homo antecessor as the ancestor of H. heidelbergensis and H. rhodesiensis, where H. antecessor which originated in Africa and went on to colonize Europe, evolving into both species due to the separation of their populations. Critics point out that one of the flaws in this theory is the possibility that the remains of H. antecessor actually belong to H. heidelbergensis.

Once Europe was colonized, H. heidelbergensis began to acquire Neanderthal features about 400,000 years ago, with the advent of the Mindel Ice Age. This, together with the strong physical resemblance to Neanderthals of the heidelbergensis found at Sima de los Huesos in Atapuerca, has been proposed as an indication that the populations of H. heidelbergensis were withdrawn to the Mediterranean peninsulas during the glacial phases, so the isolation of populations created a bottleneck that gave rise to Neanderthals.

Finally, between 230,000 and 200,000 years ago the H. heidelbergensis became extinct, being replaced by its relative, Homo neanderthalensis.

Fossils

Replica of Mauer's jaw.

The oldest fossil discovery of the species is a lower jaw (Mauer 1), found in 1907 by a mine worker at Mauer, near Heidelberg. This jaw is estimated to date to 600,000 years BP.

Later, in a cave called Caune de l'Arago, in France, the fragmentary remains of a dozen individuals were found. The most complete is the face and part of the braincase of an individual known as Tautavel man, dating to about 450,000 years BP, and closely resembling the skull of Petralona man found in a cave in Greece.

Other sites where fossils attributed to this species have been found are Steinheim (Germany), Swanscombe (England) and the Sima de los Huesos in the Sierra de Atapuerca (Spain), where 5000 fossils belonging to about 30 individuals were found, dating from 400,000 years ago, considered ancestors of the Neanderthals, remains that are very well preserved; Among them, the skull number 5 (popularly called "Miguelón") stands out, which is complete, and of which studies have recently been carried out that show a laterality in the brain (it was right-handed), and a very large pelvis. remains of an individual popularly known as "Elvis". Fossils consistent with this group have been found in China at the Daliː site, a 280,000-year-old skull and a skeleton at Jinniushan.

It should be noted that in Terra Amata (France) remains of shelters built during the time of H. heidelbergensis. These shelters were oval in shape, twenty-five feet long and twenty wide. Inside the shelter, remains of ash were found.

Fossils related to this species have been discovered in Africa, at the Bodo sites in north-eastern Ethiopia, with a more robust but similar specimen dating to 600,000 years ago, and at Kabwe, Zambia, as well as in Lake Ndutu (Tanzania). The postcranial bones match those of Arago and indicate that this was a robust, but modern form. Scientists are not unanimous when interpreting these African fossils. Some place them in the species H. heidelbergensis. Others think that the European and African fossils belong to two different species, and only the African populations, classified as Homo rhodesiensis or H. sapiens archaic, evolved until H. sapiens, while the name H. heidelbergensis would only correspond to European fossils, which present unequivocal apomorphies in the evolutionary line towards Neanderthal man. There is also no unanimity on the interpretation of the man from Petralona (Greece), which could be an H. heidelbergensis or rather a late H. rhodesiensis or another H. archaic sapiens that reached Europe from Africa along the Mediterranean coast.

Biology

Anatomy

The physical characteristics of Homo heidelbergensis present a wide range of variability among individuals from different eras and periods, and even among individuals belonging to the same population. Added to the fragmentary nature of the first remains found during the first decades, it was difficult to establish the common characteristics of the species until the discovery of a large number of relatively complete remains at the Sierra de Atapuerca site.

In this way, it has been possible to estimate that the H. heidelbergensis had a height of between 1.70 and 1.80 m, and a weight of around 95 kg. They had a more robust body than Homo sapiens, which would increase in their evolution to Homo neanderthalensis. The wide pelvis (of the same dimensions in males and females) generated a wider body and a greater separation of the legs, which, together with the arms, had modern proportions. The physical differences between the sexes show sexual dimorphism similar to that of modern humans, with a difference in height of around 10%.

The skull exhibits both archaic and modern features, with eye sockets roughly quadrangular in outline, surmounted by broad double-arched supraorbital ridges (of variable thickness), a low, wide nostril, slight facial prognathism, and relatively large jaws. robust in contrast to the reduction of the posterior teeth compared to their ancestors; the neurocranium is thick-walled (approximately 1 cm thick), with a rounded posterior part and marked prominences to a greater or lesser extent that encircled a brain of between 1,100 and 1,300 cm³.

However, as the remains get closer to H. neanderthalensis, the anatomical differences are more difficult to identify, since European populations are acquiring a greater number of Neanderthal characters. Furthermore, as mentioned above, its physical characteristics are similar to those of H. rhodesiensis, presenting difficulties regarding the taxonomic classification of the species.

Differentiation

The morphological analysis of the fossils attributed to this species has allowed us to propose two clades: the first unites the Mauer mandible, the Arago fossils and even Petralona, with a cosmopolitan group that includes the Kabwe and Bodo skulls in Africa, and Dalí and Jinniushan in China; the second includes the fossils of Steinheim, Reilingen and the Sima de los Huesos in Atapuerca, and would be more related to Neanderthal man, insofar as it presents several synapomorphies together with him.

The phenetic analysis and the study of the dental evidence confirm this differentiation, but the fact that a population as old as that of Sima de los Huesos presents very Neanderthal morphologies also forces us to consider that it could be that, The species H. neanderthalensis.

DNA Sequencing

Sequencing of the mitochondrial DNA of a femur from the Sima de los Huesos has shown a greater relationship with the Siberian fossils of the Denisovan hominid than with Neanderthal DNA, which opens the way for the hypothesis of a complex relationship between the different species of Homo in Eurasia.

Genetic analysis of the Sima de los Huesos fossils (Meyer et al., 2016) seems to suggest that H. heidelbergensis in its entirety should be included in the Neanderthal lineage, as "preneanderthal" or "archaic Neanderthal" or "early", whereas the time of divergence between the Neanderthal and modern lineages has been delayed to before the appearance of H. heidelbergensis, approximately 600,000 to 800,000 years ago, the approximate time of the demise of Homo antecessor.

Technology and organization

Lithic industry and tools

The lithic industry associated with the remains of H. heidelbergensis belongs to the Acheulean or Industry of mode II, whose appearance occurred in Africa approximately 1.5 Ma ago. This industry is characterized for being the first lithic industry in which the first bifaces appear, which implies a symmetrical and premeditated work of the stone

These tools were made with the materials available in the region, so the knowledge to make these tools was brought by the H. heidelbergensis to Europe, not the tools themselves.

In addition to these tools, in some sites in Africa and Europe several wooden spears have been found in an exceptional state of preservation, which show that this species already had throwing weapons that would allow them to hunt animals from a distance. No there is doubt about their hunting abilities, as evidenced by the "Schöningen spears" (Germany), a set of eight wooden spears dating back 400,000 years.

The oldest evidence of the continued use of bonfires dates from about 400,000 years ago, although fire is known to have been used as early as 1.4 million years ago. Starting around 400,000, evidence of the use of hearths, associated with Acheulean tools and burned bones, began to spread throughout Europe. Probably, thanks to the habitual use of homes, the H. heidelbergensis managed to spread across the European continent and inhabited it for a long period of time.

Habitat

Throughout the middle Pleistocene, various climatic changes occurred due to glacial cycles, in which the forests that covered Europe were replaced by cold steppes and vice versa. Apparently, the H. heidelbergensis inhabited both types of ecosystems, although some remains indicate that, during the glacial periods, its population was reduced to the southernmost areas of the continent, within climatic refuges.

During the interglacials, the continent was covered with temperate deciduous forests and animals associated with forest environments, such as wild boars (Sus scrofa), macaques (Macaca sylvana), deer (Cervus elaphus, Clactonian lady, Capreolus capreolus), straight-tusked elephants (Elephas antiquus), hippopotamuses (Hipoppotamus antiquus), rhinos (Stephanorhinus hemitoechus, Stephanorhinus kirchbergensis) and various bovids (Bison schoetensacki). For its part, during the glacial periods the dominant ecosystem was the sagebrush and grass steppes inhabited by plains animals such as the steppe mammoth (Mammuthus trogontheri), bison (Bison priscus), sheep (Praeobivos, Soergelia) sheep (Ovis antiqua), large deer (Praemegaloceros verticornis, Megaloceros savini) and horses (Equus germanicus, Equus mosbachensis).

The carnivores of this period were barely affected by climate changes, inhabiting cold and temperate environments with various pantherids (Panthera leo fossilis, Panthera gombaszoegensis, Panthera pardus), wolves (Canis mosbachensis), ursids (Ursus dolinensis, Ursus deningeri) and hyenas ( Crocuta crocuta).

Pop Culture

Homo Heidelbergensis was nicknamed Goliath, due to its large size, in the documentary Search for the Ultimate Survivor broadcast in 2005 by National Geographic.