̽��ֱ�� of Cambridge - Paul Mellars

What limpets can tell us about life on Mesolithic Oronsay

amb206 — Wed, 19 Aug 2015 08:00:00 +0000

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For well over 100 years, archaeologists have been working in the windswept environment of the Isle of Oronsay on the west coast of Scotland to discover more about the people who lived on this tiny patch of land as long as 6,000 years ago – and how they exploited the natural environment around them.

Oronsay is remarkable for its stark beauty and its role as a habitat for wildlife. ̽��ֱ��island is also known for its five shell middens. Heaps of ‘kitchen waste’, they were left by people living at a period known as the Mesolithic. Also found are evidence of structures and hearths used for boiling and cooking food gathered from sea and shore. These too date from the Mesolithic.

Archaeologists have identified bones and shells from at least 30 species of marine life in the debris of these ancient rubbish heaps which, by virtue of their remoteness, lay undisturbed for so long under a thick covering of sand. Easily the most abundant of the molluscs to be found in the debris of the middens is the humble limpet.

Limpets can be found clinging to rocks all around the coast of Britain. Resembling the stereotype of a Chinese hat, the shell of the mollusc is conical but with ridges running from its outside edge to the peak. Inside, the soft body of the limpet is as vulnerable as a Dalek without its armour.

In the tough history of the Scottish islands, limpets were eaten mainly at periods when other foods were scarce. Today they are used by fishermen as bait and feature on the menus of only the most adventurous free food enthusiasts.

Archaeologist Sir Paul Mellars, emeritus professor of Prehistory and Human Evolution at Cambridge, first visited Oronsay in the mid-1970s. Over the course of five field seasons, often working in driving rain and at the mercy of Scottish midges, Mellars and colleagues excavated samples of shell material from all five middens on the island.

Using Radiocarbon dating, a technique that transformed the chronologies of human prehistory, archaeologists were able to show that the middens belong to the final stage of the Mesolithic period. This finding pointed to an intensive and relatively short-lived exploitation of the island by Mesolithic communities around the fourth millennium BC.

Modern visitors to Oronsay might well ask themselves why people would have chosen to live in such a far-flung environment, at least eight miles from the mainland. “As fishermen will tell you even today, the waters around Oronsay and the bigger island of Colonsay are rich in seafood. And the calcite-rich shell sand that covers much of the islands makes the land fertile enough to grow crops,” says Mellars.

“What’s so fascinating about the Oronsay middens is that they date from a time when people were on the point of moving from being hunter-gatherers, or hunter-fisher-gatherers, to farmers. These heaps of debris give us a glimpse of lives at a time of transition.”

Mellars’ early work focused on the range and relative importance of the different food resources as revealed by the contents of the middens. Debris from both fish and shellfish was evident. Analysis of these deposits showed that one species – saithe or coalfish – accounted for more than 90% of fish bones. Among molluscs, limpets greatly predominate over other molluscs such as whelks and periwinkles.

“It’s not hard to come up with plausible explanations for the preference for limpets, which are plentiful. They taste like bits of car tyre – but they are meatier, and more nutritious, than whelks and winkles. Furthermore, limpets are a lot easier to extract from their shells. These factors combine to make limpets a more energy efficient resource,” says Mellars.

̽��ֱ��shapes of limpet shells vary according to where they are found. Limpets inhabiting the lower parts of the tidal range are generally much flatter than those occupying the higher parts of the shore. Measurements of the height of limpet shells found in the middens revealed that they had been collected almost exclusively from the lower part of the tidal range – and chiefly from the very low tide situations exposed only during spring tides.

Mellars proposed two possible explanations. Firstly, limpets from low-tide zones are tenderer than others. Secondly, continuous harvesting of limpets may have led to an over-exploitation of more easily-accessible areas of the shore. With the disappearance of limpets from the upper levels, the human population sought foodstuffs close to the low tide line.

Advances in technology are now enabling Mellars to come up with answers to other key questions – especially the question of seasonal patterns of saithe fishing and harvesting. Although abundant around Oronsay and other islands in the summer, the fish migrate into deeper water late in the autumn. This means that communities relying on marine life would need to look elsewhere for sustenance during winter and spring.

In a collaboration between the Departments of Archaeology and Earth Sciences, limpet shells from the middens were embedded in resin and then cut in half to expose the calcite interiors. ̽��ֱ��oldest material deposited by the shell is at the pointed top while the shell deposited just before the limpets were harvested lies on the outermost edge.

Rebecca Vignols, an Earth Sciences student, used a computer-controlled microdrill to obtain tiny samples of calcite from points less than half a millimetre across in a closely-packed series at the edge of the shells. To get the full picture of seasonal change at the location the limpets lived, some limpets were drilled in a detailed series right to the top of the calcite in the shell. ̽��ֱ��ratio of light and heavy isotopes in water is affected by water temperatures, and the limpets build these changes into their shells as they grow.

̽��ֱ��oxygen isotope ratios in the shell samples were measured in the Department’s mass spectrometers. In this way, the water temperatures at the time the shells were harvested could be compared with the full seasonal temperature range at the site where they lived. This data reveals that limpets were harvested throughout the winter months. Limpets may have been consumed in combination with other seasonal foodstuffs such as hazel nuts.

̽��ֱ��five middens on Oronsay are located around I km apart from each other. All are close to the beach and face east, away from the worst of the Atlantic gales. “ ̽��ֱ��spacing of the middens seems to suggest that they were made by communities who moved along the shoreline. As they exhausted the supply of limpets in one half kilometre stretch of beach, they moved on to the next, perhaps making two runs per year in order to let the molluscs regenerate. You could almost describe it as a kind of farming,” says Mellars.

No pottery has been found in the middens but hundreds of ‘limpet scoops’ were retrieved. Some are simply finger-shaped pebbles from nearby beaches; others are made from deer horn. “Horn from at least two types of red deer was used. There have never been deer on Oronsay or Colonsay, which means that the horn may have come from Islay, Rum or Skye, and would have come by boat, suggesting a flourishing trade in this raw material for tool making,” says Mellars.

Oronsay’s middens all date to a similar period late in the Mesolithic and are composed of layers of material assembled over some 300 years. ̽��ֱ��apparent ceasing of limpet harvesting, which had been a way of life for generations, marks a significant change in lifestyle. Narratives about the spread of farming have shifted radically over the years.

“There’s been huge debate about the arrival of farming in the British Isles. “When I was a young archaeologist, it was thought that farming spread up the Danube and came north as a result of colonisation. In the 1980s, it was trendy to argue that local people made the transition to farming independently or with the influence of occasional incomers,” says Mellars.

“ ̽��ֱ��consensus today, and the theory I support, is that the communities who lived on Oronsay and other islands interbred with incomers who didn’t wipe them out but introduced them to other ways of ensuring a supply of food during the lean winter months. Something a lot more palatable than limpets – such as mutton and beef!”

This research was funded jointly by the Leverhulme Trust and the McDonald Institute for Archaeological Research (Cambridge).

Next in the Cambridge Animal Alphabet, M is for a small creature that can cause a big nuisance but also tell us a lot about pollution in water.

Inset images: Oronsay (Guy Beauchamp); Limpets (Kim Freeman); Drawings of shell sampling (Rebecca Vignols); Oronsay landscape with cows (Carron Brown).

The Cambridge Animal Alphabet series celebrates Cambridge's connections with animals through literature, art, science and society. Here, L is for Limpet and what they can tell us about Mesolithic middens, seasonal changes in the Atlantic Ocean, and the lives of people living on the remote Isle of Oronsay 6,000 years ago.

These heaps of debris give us a glimpse of lives at a time of transition

Paul Mellars

Clinging on

Guy Beauchamp

Oronsay

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Strength in numbers

gm349 — Thu, 28 Jul 2011 19:01:17 +0000

New research sheds light on why, after 300,000 years of domination, European Neanderthals abruptly disappeared. Researchers from the ̽��ֱ�� of Cambridge have discovered that modern humans coming from Africa swarmed the region, arriving with over ten times the population as the Neanderthal inhabitants.

̽��ֱ��reasons for the relatively sudden disappearance of the European Neanderthal populations across the continent around 40,000 years ago has for long remained one of the great mysteries of human evolution. After 300 millennia of living, and evidently flourishing, in the cold, sub–glacial environments of central and western Europe, they were rapidly replaced over all areas of the continent by new, anatomically and genetically ‘modern’ (i.e. Homo sapiens) populations who had originated and evolved in the vastly different tropical environments of Africa.

̽��ֱ��most plausible answer to this long-debated question has now been published today, 29 July, in the journal Science by two researchers from the Department of Archaeology at Cambridge – Professor Sir Paul Mellars, Professor Emeritus of Prehistory and Human Evolution, and Jennifer French, a second-year PhD student.

By conducting a detailed statistical analysis of the archaeological evidence from the classic ‘Perigord’ region of southwestern France, which contains the largest concentration of Neanderthal and early modern human sites in Europe, they have found clear evidence that the earliest modern human populations penetrated the region in at least ten times larger numbers than those of the local Neanderthal populations already established in the same regions. This is reflected in a sharp increase in the total number of occupied sites, much higher densities of occupation residues (i.e. stone tools and animal food remains) in the sites, and bigger areas of occupation in the sites, revealing the formation of much larger and apparently more socially integrated social groupings.

Faced with this dramatic increase in the incoming modern human population, the capacity of the local Neanderthal groups to compete for the same range of living sites, the same range of animal food supplies (principally reindeer, horse, bison and red deer), and the same scarce fuel supplies to tide the groups over the extremely harsh glacial winters, would have been massively undermined. Additionally, almost inevitably, repeated conflicts or confrontations between the two populations would arise for occupation of the most attractive locations and richest food supplies, in which the increased numbers and more highly coordinated activities of the modern human groups would ensure their success over the Neanderthal groups.

̽��ֱ��archaeological evidence also strongly suggests that the incoming modern groups possessed superior hunting technologies and equipment (e.g. more effective and long-range hunting spears), and probably more efficient procedures for processing and storing food supplies over the prolonged and exceptionally cold glacial winters. They also appear to have had more wide-ranging social contacts with adjacent human groups to allow for trade and exchange of essential food supplies in times of food scarcity.

Whether the incoming modern human groups also possessed more highly developed brains and associated mental capacities than the Neanderthals remains at present a matter of intense debate. But the sudden appearance of a wide range of complex and sophisticated art forms (including cave paintings), the large-scale production of elaborate decorative items (such as perforated stone and ivory beads, and imported sea shells), and clearly ‘symbolic’ systems of markings on bone and ivory tools – all entirely lacking among the preceding Neanderthals – strongly point to more elaborate systems of social communications among the modern groups, probably accompanied by more advanced and complex forms of language.

All of these new and more complex behavioural patterns can be shown to have developed first among the ancestral African Homo sapiens populations, at least 20,0000 to 30,000 years before their dispersal from Africa, and progressive colonisation (and replacement of earlier populations) across all regions of Europe and Asia from around 60,000 years onwards.

If, as the latest genetic evidence strongly suggests, the African Homo sapiens and European Neanderthal populations had been evolving separately for at least half a million years, then the emergence of some significant contrasts in the mental capacities of the two lineages would not be a particularly surprising development, in evolutionary terms.

Professor Sir Paul Mellars, Professor Emeritus of Prehistory and Human Evolution at the Department of Archaeology, said: “In any event, it was clearly this range of new technological and behavioural innovations which allowed the modern human populations to invade and survive in much larger population numbers than those of the preceding Neanderthals across the whole of the European continent. Faced with this kind of competition, the Neanderthals seem to have retreated initially into more marginal and less attractive regions of the continent and eventually – within a space of at most a few thousand years – for their populations to have declined to extinction – perhaps accelerated further by sudden climatic deterioration across the continent around 40,000 years ago.”

Whatever the precise cultural, behavioural and intellectual contrasts between the Neanderthals and intrusive modern human populations, this new study published in Science demonstrates for the first time the massive numerical supremacy of the earliest modern human populations in western Europe, compared with those of the preceding Neanderthals, and thereby largely resolves one of the most controversial and long-running debates over the rapid decline and extinction of the enigmatic Neanderthal populations.

Volume of modern humans infiltrating Europe cited as critical factor in the demise of the Neanderthals.

Faced with this kind of competition, the Neanderthals seem to have retreated initially into more marginal and less attractive regions of the continent and eventually – within a space of at most a few thousand years – for their populations to have declined to extinction – perhaps accelerated further by sudden climatic deterioration across the continent around 40,000 years ago.

Professor Sir Paul Mellars, Professor Emeritus of Prehistory and Human Evolution at the Department of Archaeology

Image Dora Kemp, McDonald Institute for Archaeological Research

Map of the migration of modern man out of Africa. Triangles represent Aurignacian (considered the first modern humans) split-base points.

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