Human remains more than 4,000 years old have helped scientists discover the identity of its architects.

by Stuart Carter

Copyright: Jane Brayne 2004 The Boscombe Bowmen are likely to have built Stonehenge about 4300 years ago.

One thing is sure - building Stonehenge was a really tough job. Without cranes, hoists or machinery, the massive rocks were erected, some heavier than a fully-loaded truck, and they still stand undisturbed thousands of years later.. We still don't know what this mysterious configuration of rocks was for - but archaeologists have identified the architects by examining human remains more than 4,000 years old found in the area.

Stonehenge dominates Salisbury Plain in southern England and lies at the heart of an area steeped in monuments to long-forgotten pagan religions. The design evolved over many generations: first a circular ditch and bank, then a second phase of timber structures. The third phase saw the arrival of stones - the largest 23 feet tall and weighing more than 44 tons. In total, Stonehenge is made up of more than 1,500 tons of rock.

The precision with which it was built is amazing. Some believe that the massive stones were carefully aligned with stars in the sky. At some stage in its creation, the circle of upright stones was topped by huge carved rock lintels. These stones are nearly perfectly level, despite being built on sloping ground. Within the larger stones lie a circular arrangement of smaller uprights known as bluestones. And in the middle is a horseshoe with the largest of all the stones: a series of three slab constructions known as the Trilithons. Stonehenge is unique; nothing quite like it has been built before or since. But the question remains: who built it?

The suspects

There are lots of likely suspects. The first humans in Britain, at the end of the last ice-age, were primitive, stone-age hunter-gatherers. Then settlers and invaders started arriving from mainland Europe. Was Stonehenge built by ancient Britons or foreign invaders? There are clues to be found deep under the stones. Early archaeologists found deer antlers, pottery and even human remains in the area and radiocarbon dating, can determine exactly how old these artefacts are. Because they were buried directly underneath the stones, it also gives us the most likely date when Stonehenge was built.

Credit: Tom Goskar, Wessex Archaeology Pottery found by archaeologists from Wessex Archaeology.

Tests published in 1995 revealed that the final phase of Stonehenge was older then previously thought - it was built as far back as 4,000 years ago. This was the first hard evidence of a date and it knocked out the Druids as contenders since they only came to Britain around 2000 years ago. In fact, Stonehenge is so old that the first phase even predates the pyramids of Egypt. The radiocarbon date suggests that Stonehenge is the work of ancient Britons - a primitive and little-known people. At this time, 4,500 years ago, Britain was nearing the end of the Stone Age and the start of the Bronze Age. How could such primitive people have pulled off such an incredible construction project?

The strategy

The first problem any ancient builders faced was getting hold of the construction materials - in this case the stones that make up Stonehenge. There are two types of stones at Stonehenge; small ones called bluestones and larger Sarsen stones. Rocks similar to the large Sarsen stones can be found some 20 miles from Stonehenge but the bluestones are a different matter: they're not from the local area at all.

Tracing the source of the bluestones isn't easy. Under the microscope, the distinctive crystalline texture of these stones is a close match with one other location in the whole of the British Isles: the Preseli mountain range in South West Wales. The Preseli Mountains are more than 200 miles away from Stonehenge. And to make matters worse, the journey kicks off in tough, mountainous terrain - and involves crossing Britain's biggest tidal estuary, the Bristol Channel. So, how were stones weighing as much as four tons carried such a long way with primitive technology?

Archaeological evidence suggests that people from the Stonehenge era used a variety of different boats. The most common were log boats - a type of dugout canoe cut from an oak tree. An unusual discovery at Shardlow quarry near Nottingham, England in 1998 offers evidence that these boats could have carried the heavy stones found at Stonehenge. When a flood washed away the mud from what appeared to be an old tree stump, the remains of a Bronze Age log boat emerged. The boat was carrying an unexpected payload: more than half a ton of quarried rock.

These people seemingly built boat after boat and moved stone after stone hundreds of miles across open sea. The investment of time, human effort and ingenuity is almost beyond comprehension - and this from a supposedly 'primitive' people. Once the bluestones had arrived on the site they still had to be raised, but this was easy compared to raising the much larger stones and lintels. According to modern estimates, it might have taken 300 people up to three years to build Stonehenge. The work may have been spread out over generations - much like a medieval Cathedral. But what could have possibly motivated them to undertake such a huge project? Maybe the sheer size of the stones was designed to impress and tower over worshipers, reminding them of an omnipresent god - just like cathedrals thousands of years later. Stonehenge as a religious site is a theory favoured by many historians and archaeologists.

The builders, revealed

In April 2003, construction workers unearthed human remains at Boscombe Down, just three miles from Stonehenge. Flint arrow heads found with the bodies earned them the nickname The Boscombe Bowmen. Could they offer evidence about the people who were alive when Stonehenge was built?

Credit: Dave Norcott, Wessex Archaeology The grave at Boscombe Down during its excavation.

According to Andrew Fitzpatrick of Wessex Archaeology, it was only when the excavation was done that they realised there was something very unusual about the grave. Skeletons had been uncovered near Stonehenge before -, but they had either been identified as foreign visitors or bodies that were buried many years after it was constructed.

The new grave contained hundreds of bones suggesting multiple burials - which was unusual for this time period. The next clues came from human remains specialist Jackie McKinley: "One of the first things I do when I get material like this into the laboratory is lay everything out. And with quite a lot of work it was possible to work out that we had parts of seven individuals." A closer investigation of the bones of the skulls revealed that this was probably a family grave. Unfortunately, the condition of the bones meant that a genetic test is out of the question. Was there another way of uncovering the relationship between the bodies?

The breakthrough came from a new test that could pinpoint the likely location where people were born by identifying chemical markers absorbed in their teeth. The technique traces chemicals taken up by tooth enamel during childhood to reveal where someone was brought up. These traces are in all of us and come from the food we eat, the water we drink and from the general environment. The teeth enamel was tested for two separate chemicals: levels of oxygen isotopes and strontium isotopes. Each reading was then compared to a geological map of known levels of oxygen and strontium isotopes to reveal the locality of the tell-tale chemical markers.

And their teeth tests revealed an unexpected result.

The people buried thousands of years ago in this mass grave had all grown up more than 200 miles away from Stonehenge: in South Wales where the bluestones had all been hauled from. It was an incredible discovery and showed that these were the bones of at least some of the people who built Stonehenge. But could we go one step further, and actually see what the builders of Stonehenge might have looked like?

Taking the most complete skull found at the site, the scientists conducted a unique experiment on a 4300 year-old Stonehenge man. His bones were scanned into a computer, creating a 3D image of all the skull fragments. Then at Manchester University a team of experts on facial reconstruction took over.

These skilled facial anthropologists used advanced software to build layers of muscle and create a 3-dimensional model. It took many weeks of computer time but finally the mysterious and long-dead Stonehenge man was reconstructed and scientists were able to get an idea of what one of the architects might have looked like.

But one last mystery remains: why was it built? The only certainty is the stones themselves. A monument that has stood proud and immovable for thousands of years - an incredible monument created by the ingenuity of the human mind.

For more information:

Wessex Archaeology: The Boscombe Bowmen
http://www.wessexarch.co.uk/projects/wiltshire/boscombe/bowmen/index.html

English Heritage - Stonehenge
http://www.english-heritage.org.uk/server/show/nav.876