Prehistoric World

600,000

Homo ergaster's descendant, Homo heidelbergensis ('Heidelberg man'), first appeared between 800,000 and 600,000 years ago.

This was simultaneous to Homo erectus populations in sub-tropical Asia showing their first signs of anatomical development since they migrated there 1.2 million years before. Soon after this point, there were apparently evolutionary developments in features of the head that would become characteristic of modern humans, which perhaps explains why some see Homo erectus as a direct ancestor of Homo sapiens and not the dead-end branch it was.

Heidelbergensis was significantly more intelligent than erectus. The exact area that this species occupied is unknown due to insufficient fossilised remains, but it is known that it flourished in Europe and Africa for several hundred thousand years.

It is thought that many aspects of the Acheulean era (early Palaeolithic) tool case were innovated and utilised by this species. It also innovated many more advanced tools not associated with the early and middle Palaeolithic period, such as throwing spears, which is a somewhat anomalous finding. More advanced tool-making techniques of the Mousterian (middle Palaeolithic) tool case were also thought to have been innovated by this species toward the end of its presence in the fossil record. However, heidelbegensis tools were not nearly as advanced as those used by later hominids.

Recent findings in Europe also suggest that heidelbergensis may have been the first species of the Homo genus to bury their dead, but that is hotly contested at this time.

Sites where heidelbergensis appears to have produced the red pigment ochre from hematite suggest this species may have practiced art or ritual. At least toward the end of its existence, the species almost certainly controlled fire and may even have used rudimentary language.

500,000

Homo heidelbergensis spread to populate southern Europe and Africa, with a good source of remains being discovered at a system of limestone caves at Atapuerca in northern Spain. They also reached Boxgrove in West Sussex, England which at this time was a beach with limestone cliffs, part of a tidal lagoon tucked behind a headland. Horses, megaloceros (giant deer), rhinoceros, voles and wolves occupied the landscape.

Skulls from elsewhere in Europe and in Africa show that heidelbergensis was developing a large brain, and the species is now seen as a key evolutionary link between ergaster and modern humans.

400,000

Homo heidelbergensis was using throwing spears to kill large prey such as megaloceros. Such hunting transformed scavenging hominids into masters of their environment.

Bones from large animals such as rhinos, horses and hippos were covered with cut-marks where Boxgrove man in Britain used stone blades to slash and butcher the animals for their meat. Crucially, the cut marks were found beneath the tooth marks of carnivores, indicating that humans got there before the scavengers. To archaeologist Mark Roberts, who led the Boxgrove excavation, this implies the Boxgrove people were hunting, not scavenging.

Heidelbergensis also continued to thrive in Africa. A fossil skull dated to this period was found at Kabwe in Zambia - the same area in which later Homo sapiens (archaic) finds would be made.

400 - 300,000

In Asia, Homo erectus specimens from China were some of the first hominids that were discovered. The various specimens from Dragon Bone Hill, in the cave of Zhoukoudian were discovered in the late 1920s. However, all but two teeth that were sent abroad for analysis were lost in the chaos of WWII. The material included five skullcaps, several cranial and facial fragments, eleven mandibles, and 147 isolated teeth.

This material was used for the reconstruction of 'Peking Man' (so-called Homo erectus pekinensis) by F Weidenreich. A newer reconstruction has been made by I Tattersall and G Sawyer that uses fragments that are assumed to be male, as the original reconstruction used both male and female remains. The newer cranial reconstruction results in a larger cranial capacity with a more massive and projecting face, with a broader taller nasal region.

This new reconstruction is more similar to erectusfrom elsewhere in the world. The material has been dated to between 500,000 and 400,000 years ago. The five skullcaps have a mean cranial capacity of 1043 cc. The Asian erectus had become mostly isolated from African hominids, and had begun to look distinct, resulting in facial bones that were massive, mandibles that were very robust, and more robust ridges of bone with the walls of the skull greatly thickened.

Homo erectus seems to have dwindled greatly in its Asian homeland by 300,000 years. It had been, to date, the longest-surviving Homo species, but seems to have started a decline by this point. It continued to survive in the more remote region of Java and in isolated pockets in South Asia.

300,000

Homo heidelbergensis, which had spread to populate southern Europe and Africa, was beginning to use basic speech by this time, a skill which seems to have evolved progressively rather than being a sudden discovery.

The species was divided into at least two branches by the coming of a new Ice Age in the Pleistocene. As conditions changed either side of the Mediterranean, the population in Africa began to evolve along different lines to that in Europe. This evolutionary divergence may have begun as early as 600,000 years ago.

The polar ice caps were locked in a cycle of retreat and advance. When they retreated, temperatures climbed and deciduous forest covered Europe. When the ice caps advanced, temperatures plummeted and the landscape turned into snowy tundra. In order to survive these ice ages, the European population of heidelbergensis evolved physical adaptations to the cold - becoming broader and more thickset, developing wider nostrils to heat the air entering its lungs - and became neanderthalis, although there may also have been heidelbergensis populations which existed for a time alongside the new Neanderthals until the increasingly harsh conditions eventually ensured their demise.

The Neanderthals lost the tall, strapping physique of heidelbergensis and developed a short, stocky body that was an ideal shape for conserving heat. They were also extremely muscular in order to cope with the demands of a gruelling Ice Age lifestyle. This physique developed early in childhood.

The second division of heidelbergensis, in Africa, became taller and slimmer to cope with the hotter temperatures there, emerging as Homo sapiens.

In 2010 a probable third descendant of Homo heidelbergensis was discovered in Denisova Cave in the Altai Mountains of Siberia (although this descent is not certain). Perhaps more closely related to Neanderthalis than modern man, Homo denisovan seems to have evolved about the same time, and all three species were living in the area at the same time. While Neanderthalis was struggling to adapt to the European Ice Age, the Denisovans inhabited Siberia and parts of Asia, possibly alongside late H erectus populations.

A finger bone fragment of a juvenile that lived about 41,000 years ago was found along with a tooth and toe bone from two other individuals of the same population.

Further facts are slowly emerging from continued examination of the remains and DNA analysis. It seems that by 20,000 years ago, populations of H denisovan and H sapiens were interbreeding on mainland East Asia, adding a new aspect to Denisovan's survival.

Homo denisovan, Homo neanderthalis, and Homo sapiens were born from the changes triggered by the Ice Age, although Neanderthals appeared around 100,000 years earlier than H sapiens.

All images copyright © BBC or affiliates unless otherwise stated. No breach of copyright is intended or inferred. Text copyright © P L Kessler, adapted from numerous sources and notes, most notably the BBC tv series, Walking with Cavemen, and subsequent archaeological discoveries. An original feature for the History Files.