Cows left home for Stonehenge

What do the BGS, Bonekickers, Patricia Cornwell and the Metropolitan Police have in common? Answer - they have all used strontium isotopes to identify dead bodies. Ted Nield reports from the BA.

Geoscientist Online 10 September 2008

Stonehenge inspires awe, even in the 21st Century. Imagine how much more incredible it must have looked to Bronze Age people over 4000 years ago. What was its function and from how faraway did it draw people? Was it a religious site? Isotope analysis of human teeth shows that people came to Stonehenge from across Europe and that there must have been a large communication network associated with it.

Cattle remains found near Stonehenge were also not local. New results published in June this year revealed that they must have been brought from areas as far away as Wales. This shows that animals were brought by individual groups of people coming to the Stonehenge area from afar. Scientists can use the animal remains to trace their owners, and so shed light on the communication networks in use during Neolithic time, Dr Jane Evans (Head of Archaeology Studies, BGS) told the BA today.

The NERC Isotope Geosciences Laboratory at BGS is a global leader in strontium isotope analysis and is increasingly using this technique to tell if someone is "local" to the region in which they are found, and to reduce or identify their childhood origins if they are not. What is important about this technique is that, for the first time, scientists are able to look at evidence of origin from the human remains, and not depend upon artefacts buried with them - which may or may not relate to their geographic homeland.

Strontium in teeth and bones

The principle of using strontium isotopes to trace origins is based on the fact that the isotope composition of strontium varies, predominantly in relation to age and geochemical composition of soil, which is, in turn, often related to underlying geology. These variations make their way into the food chain through plant uptake. Once in plants the strontium is transmitted through the food chain. Strontium is chemically similar to calcium and hence is deposited in tooth and bone. So, by analysing the isotope composition of strontium in teeth scientists can find out the isotope composition of the diet at the time when that tooth formed. In archaeological studies the target material is tooth enamel as this is resistant to alteration during burial, unlike bone, and this means that human studies are restricted to the period during which tooth enamels forms - ie childhood to early adulthood. In the case of animals, the technique can be used to look at the progressive formation into maturity for animals such as herbivores.

When an unusual, multiple burial of Bronze Age individuals was discovered at Boscombe Down near Stonehenge, strontium isotopes were used to tell if the group of individuals came from the area of Stonehenge. Evans told the BA: “We analysed two teeth from each of three adult males, which meant we could look at the early childhood and early teenage period of their lives. The results provided the first evidence of childhood migration. The men had a common history. None of them came from the Stonehenge area and each of them had moved during their childhood. Their early childhood was spent in an area of relatively unusual Sr isotope composition which, within Britain, would restrict them to areas of older rocks, the nearest of which are found in Wales, meaning that they had travelled a minimum of 150km. Sites further away in the UK and on the continent are also possible.”

“This example demonstrates the power of this technique; before isotope analysis we knew we had three adult males in a common grave, of unknown origin, that might be related. After isotope analysis we know that all the men have common background, that they came from the same area and made the same journey at the same time of their lives and that they came from at least 150 km away.”

The main development needed now, says Evans, is to develop good reference maps so that isotope composition of tooth enamel can be matched accurately with possible areas of origin. “Coverage is patchy at the moment. The British Geological Survey in collaboration with Bradford University is developing maps designed to support archaeological research of this kind. The maps may also be useful for modern forensic studies. For example, mineral water can be fingerprinted using its strontium isotope composition.”

Cows left home for Stonehenge

What do the BGS, Bonekickers, Patricia Cornwell and the Metropolitan Police have in common? Answer - they have all used strontium isotopes to identify dead bodies. Ted Nield reports from the BA.

Geoscientist Online 10 September 2008

Strontium in teeth and bones

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