Homo heidelbergensis

These humans evolved in Africa but by 500,000 years ago some populations were in Europe. They lived and worked in co-operative groups, hunted large animals and made a variety of tools including stone hand axes and wooden spears set with stone spearheads.

_{Photogrammetry model of Homo heidelbergensis skull cast. View full screen on Pedestal 3D.}

Background of discovery

Age

This species lived between 300,000 and 600,000 years ago. The African fossils tend to be older than those from Europe. Fossils from Gran Dolina in Spain date to 800,000 years old, and may be Homo heidelbergensis or a different species, Homo antecessor.

Important fossil discoveries

In 1907, an ancient human jaw was discovered in a quarry at Mauer, a village near Heidelberg, Germany. The jaw had small, human-like teeth but was unlike modern human jaws in being extremely large and heavy boned. The unique features of this Mauer 1 jaw led to it being named a new species the following year. However, the species Homo heidelbergensis has only become more accepted since the end of the 20th century with the discovery of additional fossils that had features intermediate between those of earlier and later human species.

Important specimens:

• Boxgrove 1 – a tibia (shinbone) discovered in 1993 in Boxgrove, West Sussex, England. This shinbone has been gnawed at each end by an ancient carnivore but the remaining bone shows its owner was more strongly built than modern humans. The large ridges which run down the back of the bone (shown here) are places where muscles attach to the bone and indicate that this individual had very large and powerful leg muscles.
• ‘Kabwe’ or ‘Broken Hill 1’ – skull discovered in 1921 in Kabwe (formerly Broken Hill), Zambia. This skull was the first fossil of a human ancestor to be discovered in Africa. It combines primitive features such as a wide face, thick arching brow ridges and a sloping forehead with a large brain capacity of 1280 cubic centimetres. The date of this specimen is uncertain but it may be 300,000 years old. This individual had significant tooth decay and a number of associated abscesses had decayed the upper jaw bone. Significant dental decay such as this was unusual in our ancestors prior to the development of agriculture approximately 10,000 years ago when more sugars and starchy foods were included in the diet.
• Saldanha – a skullcap discovered in 1953 in Elandsfontein, South Africa. This skullcap closely resembles the Broken Hill 1 skull in having large brow ridges, a broad, sloping forehead and a rear skull wall that is vertical rather than rounded or sloping.
• Arago 21 and Arago – skull and lower jaw discovered in Arago Caves, Tautavel, France. Excavations since 1964 have revealed a number of human fossils at Arago including this skull and jaw from different individuals. Thousands of stone tools and the bones of many types of animals have also been uncovered at this site. The Arago 21 skull is relatively complete but it was distorted either before or during fossilisation. Its features are typical of this species but its size and robust facial features suggest that it is the skull of a young male. It has been dated as being between 250,000 and 400,000 years old.
• Mauer 1 – a lower jaw discovered in 1907 in Mauer, near Heidelberg, Germany. This jaw is the ‘type specimen’ or official representative of this species. It was discovered by workers at a gravel quarry which had previously yielded many fossils of extinct mammals. Lying at a depth of about 24 metres, its age is estimated to be between 400,000 and 600,000 years old.
• The remains of at least 6 individuals found at the site of Gran Dolina, Atapuerca, in Spain. They lived about 800,000 to 1 million years ago in Europe and are the oldest human remains found in that continent. Although many experts consider these remains to be part of an early and variable Homo heidelbergensis population, the discoverers believe the fossils are different enough to be given a new species name Homo antecessor.

What the name means

Homo heidelbergensis means ‘Heidelberg Man’. Homo, is the Latin word for ‘human’ or ‘man’ and heidelbergensis is the latinised word for ‘Heidelberg’, the city in Germany where the first Homo heidelbergensis fossil was discovered in 1907.

Distribution

Fossils of this species have been found scattered across Africa and Europe. A fossilised skullcap discovered in northern India’s Narmada Valley may also be Homo heidelbergensis and if so, currently represents the easternmost occurrence of this species. Important sites include Lake Turkana, Bodo, Ndutu, Kabwe, Elandsfontein, Petralona, Mauer, Steinheim, Arago, Boxgrove, Swanscombe and Narmada.

Relationships with other species

Most fossils now known as Homo heidelbergensis were previously known as either Homo erectus, Homo neanderthalensis or ‘archaic’ Homo sapiens. With the discovery of many more fossils over the last few decades, many researchers now accept Homo heidelbergensis as a separate species, although the designation of some fossils is still debated since they possess features that are transitional between earlier and later species.

Homo heidelbergensis began to develop regional differences that eventually gave rise to two species of humans. European populations of Homo heidelbergensis evolved into Homo neanderthalensis (the Neanderthals) while a separate population of Homo heidelbergensis in Africa evolved into our own species, Homo sapiens.

Some European fossils have features that indicate they were intermediate between earlier Homo heidelbergensis and the later Neanderthal people. Their classification is therefore debated – are they Homo heidelbergensis or are they early Homo neanderthalensis?

Examples of debated classification: Homo heidelbergensis or early Homo neanderthalensis?

• Steinheim – skull discovered in1933 in Steinheim, Germany. The face of the Steinheim skull is shaped like those of other Homo heidelbergensis individuals although it is less robust and may belong to an adult female. The cranium, however, is Neanderthal-like as it is very rounded at the rear and has a slight depression in the occipital bone at the back of the skull.
• Swanscombe – cranium discovered in 1935, 1936 and 1955 (in three separate pieces) in Swanscombe, England. The face of the cranium has not been found but the back of the cranium resembles the Steinheim skull.

More recently, fossils remains found at Gran Dolina in Spain have cast doubt on this interpretation. Although many experts consider these remains to be part of an early and variable Homo heidelbergensispopulation, the discoverers believe the fossils are different enough to be given a new species name Homo antecessor. They also claim they are the last common ancestor of Neanderthals and Homo sapiens. This scenario sees European Homo heidelbergensis moved to a side branch from modern humans as they are the descendants of Homo antecessor and the ancestor of Neanderthals. African Homo heidelbergensis would require a name change.

Key physical features

Homo heidelbergensis fossils tend to have features that are intermediate between those of Homo ergaster and either Homo neanderthalensis or Homo sapiens.

Body size and shape

• fossil evidence regarding body size and shape is currently limited but leg bones indicate they were tall, reaching about 180 centimetres in height and had relatively long legs like their earlier ancestor, Homo ergaster.
• the shinbone’s thickness and bony ridges indicate that these people were strongly built.

Brain

• brain was large, averaging approximately 1250 cubic centimetres in size, representing 1.9% of their body weight
• frontal and parietal lobes of the brain were enlarged and may indicate an increase in brain complexity

Skull

• small post-orbital constriction behind the eye sockets.
• a moderate, double arched brow ridge and a short, sloping forehead lay above the eyes. The brow ridge was more arched than that of the earlier species, Homo ergaster. The sloping forehead resembled those found in earlier species rather than the vertical foreheads of modern humans.
• nasal opening was relatively wide

Jaws and teeth

• jaws were shorter than those of earlier species resulting in a face with only a slight projection
• some members of this species possessed a gap, called the retromolar space, behind the third molars (or wisdom teeth) at the back of the jaw. Others had only a tiny gap or no gap.
• lower jaw was strongly built for the attachment of strong chewing muscles
• as with earlier species, the lower jaw did not have a protruding, pointed chin
• teeth were arranged in the jaw so that they formed a parabolic shape (curved at the front then splayed out toward the back)
• teeth were smaller than those of earlier species but were larger than those of modern humans

Limbs

• lower legs were relatively long. Limb proportions such as these represent an adaptation to tropical conditions as they provide a larger skin surface to help cool the body. These limb proportions are similar to those found later in Homo sapiens and contrast with the short lower legs that developed in the Neanderthals.
• leg bones tended to be thick and strongly built.

Lifestyle

Culture

Homo heidelbergensis people spread out of Africa and had established populations in Europe and possibly also in southern Asia by about 500,000 years ago. By about 300,000 years ago, regional differences began to develop as they adapted to their new environments.

The tools made by Homo heidelbergensis were mostly used for hunting and butchery. Most of their tools were of the type previously used by Homo ergaster. These were large stone tools with flakes removed from two sides to produce the bifacial stone hand axes, cleavers and carvers classified as Mode 2 technology. Some later populations are known to have also made tools from deer antler, bone and wood. These materials were modified into scrapers, hammers and sophisticated wooden throwing spears.

Fire was used, although further evidence is needed to establish whether this was a controlled use of fire.

Animal hide clothing may have been worn, especially by populations living in the cooler European areas. However, direct evidence of clothing is difficult to obtain since it is non-durable and tends to quickly perish. No direct evidence of clothing currently exists.

Environment and diet

Between 600,000 and 200,000 years ago, the climates of Africa and Europe experienced a series of warm and cool phases and the move from Africa to Europe subjected these people to generally colder climates. About 300,000 years ago, a severe cold, dry period began and the Sahara became a barrier to movement between Africa and Eurasia, although movement may have been possible between Europe and northern Asia. At this time, populations in Africa and in Europe were isolated from one another and regional differences began to appear.

Homo heidelbergensis hunted large animals for food although the hides may also have been useful, especially in colder areas. The fossilised bones of these animals have shown that large animals including rhinos, hippopotamus, bears, horses and deer were targeted. These animals were skilfully hunted then butchered in an orderly fashion that suggests that these people were working in co-operative groups.