The human body's size and shape has gone through four main stages of evolution.

This is according to a study of fossils found at Sima de los Huesos in Sierra de Atapuerca in northern Spain.

Dated to around 430,000 years ago, this site preserves the largest collection of human fossils found to date anywhere in the world.

The human body's size and shape has gone through four main stages in a pattern of 'mosaic evolution'. This is according to a study of fossils found at Sima de los Huesos in Sierra de Atapuerca in northern Spain. Pictured here are various postcranial skeletons - the bones of the body other than the skull

STAGES OF HUMAN EVOLUTION Around 400,000 to 500,000 years ago, archaic humans split off from other groups of that period living in Africa and East Asia, ultimately settling in Eurasia. This was the first stage of evolution. Once settled, they evolved characteristics that would come to define the Neanderthal lineage, in the second stage of evolution. The Atapuerca fossils represent the third stage, with tall, wide and robust bodies and an exclusively terrestrial bipedalism, with no evidence of tree-dwelling behaviors. This same body form was likely shared with earlier members of our genus, such as Homo erectus, as well as some later members, including the Neanderthals. Several hundred thousand years later, modern humans - who had evolved in Africa - settled in Eurasia. Advertisement

The researchers found that the Atapuerca individuals were relatively tall, with wide, muscular bodies and less brain mass relative to body mass compared to Neanderthals.

But the Atapuerca humans shared many anatomical features with the later Neanderthals not present in modern humans.

And a study of their postcranial skeletons - the bones of the body other than the skull - found that they are closely related to Neanderthals.

'This is really interesting since it suggests that the evolutionary process in our genus is largely characterised by stasis (i.e. little to no evolutionary change) in body form for most of our evolutionary history,' wrote Rolf Quam, study author at Binghamton University.

Comparison of the Atapuerca fossils with the rest of the human fossil record suggests that the evolution of the human body has gone through four main stages.

The Atapuerca fossils represent the third stage, with tall, wide and robust bodies and an exclusively terrestrial bipedalism, with no evidence of tree-dwelling behaviors.

This same body form was likely shared with earlier members of our genus, such as Homo erectus, as well as some later members, including the Neanderthals.

This body form seems to have been present in the genus Homo for over a million years, the researchers claim.

The Atapuerca fossils represent the third stage, with tall, wide and robust bodies and an exclusively terrestrial bipedalism, with no evidence of tree-dwelling behaviors. This same body form was likely shared with the Neanderthals. Pictured left is an artist's impression of Atapuerca individuals and on the right, a Neanderthal

Comparison of the Atapuerca fossils with the rest of the human fossil record suggests that the evolution of the human body has gone through four main stages

It was not until the appearance of our own species, Homo sapiens, when a new taller, lighter and narrower body form emerged.

The researchers suggest that the Atapuerca humans offer the best look at the general human body shape and size during the last million years before the advent of modern humans.

GENES FROM NEANDERTHALS MAY BE TO BLAME FOR MODERN DISEASES Neanderthals and modern humans are thought to have co-existed for thousands of years and interbred. These 'legacy' genes have been linked to an increased risk from cancer and diabetes by new studies looking at our evolutionary history. However, it is not all bad news, as other genes we inherited from our species' early life could have improved our immunity to diseases which were common at the time, helping humans to survive. Speaking to MailOnline, professor Chris Stringer, research leader in human origins at the Natural History Museum in London, said: 'We got a quick fix to our own immune system by breeding with Neanderthals which helped us to survive. 'Studies have also already been published which show that humans outside of Africa are more vulnerable to Type 2 diabetes, and that is because we bred with Neanderthals, while those who stayed inside Africa didn't.' Last year researchers from Oxford and Plymouth universities announced that genes thought to be risk factors in cancer had been discovered in the Neanderthal genome, and in January Nature magazine published a paper from Harvard Medical School suggesting that a gene which can cause diabetes in Latin Americans came from Neanderthals. Advertisement

The discovery at the Sima de los Huesos site in Spain's Atapuerca Mountains has allowed scientists to better understand pre-human evolution during the Middle Pleistocene period - a time in which the path of hominin evolution has been controversial and fiercely debated

An earlier study of fossils in the area by the same group revealed how Neanderthals developed their distinctive teeth before their brains, using them as a third hand for holding objects.

The study adds to theories that our ancestors evolved their characteristic looks slowly, and intermittently, over hundreds of thousands of years.

The discovery at the Sima de los Huesos site in Spain's Atapuerca Mountains has allowed scientists to better understand pre-human evolution during the Middle Pleistocene period - a time in which the path of hominin evolution has been controversial and fiercely debated

Pictured on the left is an impression of a Neanderthal and on the right an artist's impression of Homo Erectus

Neanderthals’ trademark facial features took shape as a first step in their evolution, while their other defining features came along later, and not all at once, the researchers said.

This suggests the earliest Neanderthals used their jaws in a particular way for chewing as well as for holding objects..

THE COMPLEX EVOLUTION OF MAN 55 million years ago - First primitive primates evolve 15 million years ago - Hominidae (great apes) evolve from the ancestors of the gibbon 8 million years ago - First gorillas evolve. Later, chimp and human lineages diverge 5.5 million years ago - Ardipithecus, early 'proto-human' shares traits with chimps and gorillas 4 million years ago - Australopithecines appeared. They had brains no larger than a chimpanzee's 2.8 million years ago - LD 350-1 appeared and may be the first of the Homo family 2.7 million years ago - Paranthropus, lived in woods and had massive jaws for chewing 2.3 million years ago - Homo habalis first thought to have appeared in Africa 1.85 million years ago - First 'modern' hand emerges 1.8 million years ago - Homo ergaster begins to appear in fossil record 1.6 million years ago - Hand axes become the first major technological innovation 800,000 years ago - Early humans control fire and create hearths. Brain size increases rapidly 400,000 years ago - Neanderthals first begin to appear and spread across Europe and Asia 200,000 years ago - Homo sapiens - modern humans - appear in Africa 40,0000 years ago - Modern humans reach Europe Advertisement

Juan-Luis Arsuaga, a paleontologist at the Complutense University of Madrid, claims the findings were consistent with a 'Game of Thrones' evolutionary saga.

In this scenario communities of humans, equivalent to 'houses' in the sci-fi series, would compete for habitable areas more than 400,000 years ago.

Study lead author Juan-Luis Arsuaga, said: ‘The Middle Pleistocene was a long period, of about half a million years, during which hominin evolution didn’t proceed through a slow process of change with just one kind of hominin quietly evolving towards the classic Neanderthal.’

Co-author of the study published in Science, Ignacio Martinez, Professor of Paleontology at the University of Alcalá, added: ‘With the skulls we found it was possible to characterise the cranial morphology of a human population of the European Middle Pleistocene for the first time.’

Around 400,000 to 500,000 years ago, archaic humans split off from other groups of that period living in Africa and East Asia, ultimately settling in Eurasia.

Once settled, they evolved characteristics that would come to define the Neanderthal lineage.

Several hundred thousand years later, modern humans - who had evolved in Africa - settled in Eurasia.

They interbred with the Neanderthals, but showed signs of reproductive incompatibility.

Because of this, modern humans eventually replaced Neanderthals.

The degree of divergence between Neanderthals and modern humans over such a short period of time has long puzzled scientists.

It has, until now, been difficult to fill in the gaps because the European fossil record is isolated and dispersed. However, samples at the Sima de los Huesos site are different.