̽��ֱ�� of Cambridge - Colin Shaw

New CT imaging facility reveals 'internal secrets'

lw355 — Sun, 15 Feb 2015 00:00:00 +0000

̽��ֱ��Cambridge Biotomography Centre (CBC), which launched early in 2015, houses the latest high-resolution computed tomography (CT) scanner available on the market. One of only a handful in the country, the CT scanner uses X-rays to measure density differences within objects, generating a precise three-dimensional reconstruction of the internal and external architecture of almost any object or specimen.

Already being used to scan everything from ancient Egyptian leg bones and fossils hidden inside rocks, to the muscle and skeletons within dead rats, the facility has been launched with the intention of providing not just Cambridge researchers but also the wider international research community with the chance to unlock their material’s closely held secrets.

“Although CT is frequently used in hospitals, this type of imaging has only recently become available to researchers,” explained Dr Colin Shaw, one of the leaders of the facility.

His work in the Department of Archaeology and Anthropology is analysing the behaviour of our prehistoric ancestors through the analysis of their bones. “A continuum of different behaviours that stretches from couch potato to ultramarathon runner puts stresses and strains on bones which can be measured to reconstruct what our lives were like in the past,” he explained.

However, the information is hidden deep within the honeycomb-like structure of the bone itself, and the ancient remains he studies are too precious to be broken open. “For objects like these, the ability to do this non-invasively without cutting or slicing is a real benefit,” he added. “It means we can carry on studying the object long after the measurements have been made.”

̽��ֱ��CBC houses a Nikon Metrology XT H 225 ST High Resolution CT Scanner and is a multi-user research facility that supports Cambridge researchers as well as the broader national and international academic community. ̽��ֱ��Center resides in the Department of Zoology, and was funded by the School of the Biological Sciences, the Departments of Zoology and Physiology, Development and Neuroscience, and the PAVE Research Group of the Department of Archaeology and Anthropology.

A new imaging facility offers researchers in Cambridge and beyond the chance to see what lies within objects, without breaking them open.

A continuum of different behaviours that stretches from couch potato to ultramarathon runner puts stresses and strains on bones which can be measured to reconstruct what our lives were like in the past.

Colin Shaw

Ket Smithson

CT Scan

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Hunter-gatherer past shows our fragile bones result from physical inactivity since invention of farming

fpjl2 — Mon, 22 Dec 2014 20:02:37 +0000

New research across thousands of years of human evolution shows that our skeletons have become much lighter and more fragile since the invention of agriculture - a result of our increasingly sedentary lifestyles as we shifted from foraging to farming.

̽��ֱ��new study, published today in the journal PNAS, shows that, while human hunter-gatherers from around 7,000 years ago had bones comparable in strength to modern orangutans, farmers from the same area over 6,000 years later had significantly lighter and weaker bones that would have been more susceptible to breaking.

Bone mass was around 20% higher in the foragers - the equivalent to what an average person would lose after three months of weightlessness in space.

After ruling out diet differences and changes in body size as possible causes, researchers have concluded that reductions in physical activity are the root cause of degradation in human bone strength across millennia. It is a trend that is reaching dangerous levels, they say, as people do less with their bodies today than ever before.

Researchers believe the findings support the idea that exercise rather than diet is the key to preventing heightened fracture risk and conditions such as osteoporosis in later life: more exercise in early life results in a higher peak of bone strength around the age of 30, meaning the inevitable weakening of bones with age is less detrimental.

There is, in fact, no anatomical reason why a person born today could not achieve the bone strength of an orangutan or early human forager, say researchers; but even the most physically active people alive are unlikely to be loading bones with enough frequent and intense stress to allow for the increased bone strength seen in the ‘peak point’ of traditional hunter-gatherers and non-human primate bones.

“Contemporary humans live in a cultural and technological milieu incompatible with our evolutionary adaptations. There’s seven million years of hominid evolution geared towards action and physical activity for survival, but it’s only in the last say 50 to 100 years that we’ve been so sedentary - dangerously so,” said co-author Dr Colin Shaw from the ̽��ֱ�� of Cambridge’s Phenotypic Adaptability, Variation and Evolution (PAVE) Research Group.

“Sitting in a car or in front of a desk is not what we have evolved to do.”

̽��ֱ��researchers x-rayed samples of human femur bones from the archaeological record, along with femora from other primate species, focusing on the inside of the femoral head: the ball at the top of the femur which fits into the pelvis to form the hip joint, one of the most load-bearing bone connections in the body.

Two types of tissue form bone: the cortical or ‘hard’ bone shell coating the outside, and the trabecular or ‘spongy’ bone: the honeycomb-like mesh encased within cortical shell that allows flexibility but is also vulnerable to fracture.

̽��ֱ��researchers analysed the trabecular bone from the femoral head of four distinct archaeological human populations representing mobile hunter-gatherers and sedentary agriculturalists, all found in the same area of the US state of Illinois (and likely to be genetically similar as a consequence).

̽��ֱ��trabecular structure is very similar in all populations, with one notable exception: within the mesh, hunter-gatherers have a much higher amount of actual bone relative to air.

“Trabecular bone has much greater plasticity than other bone, changing shape and direction depending on the loads imposed on it; it can change structure from being pin or rod-like to much thicker, almost plate-like. In the hunter-gatherer bones, everything was thickened,” said Shaw.

This thickening is the result of constant loading on the bone from physical activity as hunter-gatherers roamed the landscape seeking sustenance. This fierce exertion would result in minor damage that caused the bone mesh to grow back ever stronger and thicker throughout life - building to a ‘peak point’ of bone strength which counter-balanced the deterioration of bones with age.

Shaw believes there are valuable lessons to be learnt from the skeletons of our prehistoric predecessors. “You can absolutely morph even your bones so that they deal with stress and strain more effectively. Hip fractures, for example, don’t have to happen simply because you get older if you build your bone strength up earlier in life, so that as you age it never drops below that level where fractures can easily occur.”

Other theories for humans evolving a lighter, more fragile skeleton include changes in diet or selection for a more efficient, lighter skeleton, which was never reversed.

While the initial switch to farming did cause a dip in human health due to monoculture diets that lacked variety, the populations tested were unaffected by this window in history. “Of course we need a level of calcium to maintain bone heath, but beyond that level excess calcium isn’t necessary,” said Shaw.

̽��ֱ��research also counters the theory that, at some point in human evolution, our bones just became lighter - perhaps because there wasn’t enough food to support a denser skeleton. “If that was true, human skeletons would be entirely distinct from other living primates. We’ve shown that hunter-gatherers fall right in line with primates of a similar body size. Modern human skeletons are not systemically fragile; we are not constrained by our anatomy.”

“ ̽��ֱ��fact is, we’re human, we can be as strong as an orangutan - we’re just not, because we are not challenging our bones with enough loading, predisposing us to have weaker bones so that, as we age, situations arise where bones are breaking when, previously, they would not have” Shaw said.

While the 7,000-year-old foragers had vastly stronger bones than the 700-year-old farmers, Shaw says that neither competes with even earlier hominids from around 150,000 years ago. “Something is going on in the distant past to create bone strength that outguns anything in the last 10,000 years.”

̽��ֱ��next step for Shaw and colleagues will be to provide insight into the kind of mobility that gave our ancient ancestors such powerful physical strength.

Inset GIF: CT scan of the femoral head of a hunter-gatherer hip bone

Latest analysis of prehistoric bones show there is no anatomical reason why a person born today could not develop the skeletal strength of a prehistoric forager or a modern orangutan. Findings support the idea that activity throughout life is the key to building bone strength and preventing osteoporosis risk in later years, say researchers.

Sitting in a car or in front of a desk is not what we have evolved to do

Colin Shaw

Forager past shows our fragile bones result from physical inactivity since invention of farming

Colin Shaw and Timothy Ryan

Hunter-gatherer bone mass (left) compared with agriculturalist bone mass (right)

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From athletes to couch potatoes: humans through 6,000 years of farming

amb206 — Tue, 08 Apr 2014 09:00:10 +0000

Human bones are remarkably plastic and respond surprisingly quickly to change. Put under stress through physical exertion – such as long-distance walking or running – bones gain in strength as the fibres are added or redistributed according to where strains are highest. ̽��ֱ��ability of bone to adapt to loading is shown by analysis of the skeletons of modern athletes, whose bones show remarkably rapid adaptation to both the intensity and direction of strains.

Because the structure of human bones can inform us about the lifestyles of the individuals they belong to, they can provide valuable clues for biological anthropologists looking at past cultures. Research by Alison Macintosh, a PhD candidate in Cambridge ̽��ֱ��’s Department of Archaeology and Anthropology, shows that after the emergence of agriculture in Central Europe from around 5300 BC, the bones of those living in the fertile soils of the Danube river valley became progressively less strong, pointing to a decline in mobility and loading.

Macintosh will present some of her results at the Annual Meeting of the American Association of Physical Anthropologists in Calgary, Alberta on 8-12 April, 2014. She will show that mobility and lower limb loading in male agriculturalists declined progressively and consistently through time and were more significantly affected by culture change in Central Europe than they were in females.

Work published by biological anthropologist Dr Colin Shaw (also Cambridge ̽��ֱ��) has enabled Macintosh to interpret this male decline in relation to Cambridge ̽��ֱ�� students. Using Shaw’s study of bone rigidity among modern Cambridge ̽��ֱ�� undergraduates, Macintosh suggests that male mobility among earliest farmers (around 7,300 years ago) was, on average, at a level near that of today’s student cross-country runners. Within just over 3,000 years, average mobility had dropped to the level of those students rated as sedentary, after which the decline slowed.

“Long-term biomechanical analyses of bones following the transition to farming in Central Europe haven’t been carried out. But elsewhere in the world they show regional variability in trends. Sometimes mobility increases, sometimes it declines, depending on culture and environmental context. After the transition to farming, cultural change was prolonged and its pace was rapid. My research in Central Europe explores whether – and how – this long term pressure continued to drive adaptation in bones,” said Macintosh.

Archaeological evidence has shown that the gradual intensification of agriculture was accompanied by rising production and complexity of metal goods, technological innovation and the extension of trade and exchange networks. “These developments are likely to have brought about changes in divisions of labour by sex and socioeconomic organisation as men and women began to specialise in certain tasks and activities – such as metalworking, pottery, crop production, tending and rearing livestock,” said Macintosh.

“I’m interested in how the skeleton adapted to people's specific behaviours during life, and how this adaptation can be used to reconstruct long-term changes in behaviour and mobility patterns with cultural diversification, technological innovation, and increasingly more complex and stratified societies since the advent of farming.”

As a means of tracking changes in the structure of bones over time, Macintosh laser-scanned skeletons found in cemeteries across Central Europe, concentrating in particular on an analysis of engineering-based cross-sectional geometric properties as measures of the loading imposed on the lower limb bones during life. Her research took her to Germany, Hungary, Austria, the Czech Republic and Serbia. ̽��ֱ��earliest skeletons she examined date from around 5300 BC and the most recent from around 850 AD – a time span of 6,150 years.

Using a portable desktop 3D laser surface scanner to scan femora and tibiae, she found that male tibiae became less rigid and that bones in both males and females became less strengthened to loads in one direction more than another, such as front-to-back in walking. These findings all indicate a drop in mobility. In other words, it is likely that the people to whom the skeletons belonged became, over generations, less intensely active and probably covered less distance, or carried out less physically demanding tasks, than those who had lived before them.

“Both sexes exhibited a decline in anteroposterior, or front-to-back, strengthening of the femur and tibia through time, while the ability of male tibiae to resist bending, twisting, and compression declined as well,” said Macintosh.

“My results suggest that, following the transition to agriculture in Central Europe, males were more affected than females by cultural and technological changes that reduced the need for long-distance travel or heavy physical work. This also means that, as people began to specialise in tasks other than just farming and food production, such as metalworking, fewer people were regularly doing tasks that were very strenuous on their legs."

Although there was some evidence for declining mobility in females as well, trends were inconsistent through time in most properties. Macintosh believes that this variation may indicate that women in these early farming cultures were performing a great variety of tasks – multi-tasking, in fact – or at least undertaking fewer tasks necessitating significant lower limb loading. There is evidence from two of the earliest cemeteries studied that females were using their teeth in processing activities to carry out tasks unlikely to have loaded their lower limbs much.

Interesting comparisons can be made between the archaeological evidence from Central European skeletons dating from around 7,300-1,150 years ago and data from modern farming populations elsewhere in the world.

A study by Panter-Brick in 1996 found that relative workload (as exhibited by time allocation and energy expenditure) between males and females in modern farming populations is much more variable than in foraging groups. As in early Central European farming communities, higher physical activity is recorded among males than females in Indian and Nepalese farming communities, but females have a higher relative workload than males in farming communities in the Upper Volta and the Gambia.

“This variability in the sexual division of labour in living agro-pastoralist groups shows the importance of context, ecology, and various cultural factors on sex differences in physical activity. So it is important when studying long-term trends in behavioural change between the sexes that the geographic region is kept small, to help control for some of this variability,” said Macintosh.

Female skeletons showed a major change in femoral bending and torsional rigidity from the Bronze Age into the Iron Age – between about 1450 BC and 850 BC in the samples studied – when women had the strongest femora of all the females examined in the study. This could be because the Iron Age sample included skeletons of Hungarian Scythians, a group for whom large animal husbandry, horsemanship and archery were particularly important. Scythian females are thought to have performed heavy physical work and were known to participate in at combat.

“However, if this high Iron Age female bone strength in the femur was due to high mobility, it would also probably be visible in the tibia as well, which it was not. In that case, it could be something other than mobility that is driving this Iron Age female bone strength, possibly a difference in body size or genetics,” said Macintosh.

Because the skeleton holds a record of the loading it experiences during life, it can provide important clues as to the behaviour of past people through prolonged cultural change. Overall, in the first 6,150 years of farming in Central Europe, the prosperity generated by intensive agriculture drove socioeconomic change and allowed for people to specialise in tasks other than food production.

Macintosh said: "In Central Europe, adaptations in human leg bones spanning this time frame show that it was initially men who were performing the majority of high-mobility tasks, probably associated with tending crops and livestock. But with task specialisation, as more and more people began doing a wider variety of crafts and behaviours, fewer people needed to be highly mobile, and with technological innovation, physically strenuous tasks were likely made easier. ̽��ֱ��overall result is a reduction in mobility of the population as a whole, accompanied by a reduction in the strength of the lower limb bones."

Inset images: Cambridge ̽��ֱ�� cross-country runners (Cambridge ̽��ֱ�� Hare & Hounds); 3D model of an Early Neolithic femur; Bronze Age infant urn burial from Ostojićevo, National Museum of Kikinda in Serbia; wheatfield in modern day Kikinda, northern Serbia (all Alison Macintosh)

Research into lower limb bones shows that our early farming ancestors in Central Europe became less active as their tasks diversified and technology improved. At a conference today, Cambridge ̽��ֱ�� anthropologist Alison Macintosh will show that this drop in mobility was particularly marked in men.

My results suggest that, following the transition to agriculture in Central Europe, males were more affected than females by cultural and technological changes.

Alison Macintosh

Moravian Museum

Early Neolithic 35-40 year old male from Vedrovice, Czech Republic

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Caveman about the house

bjb42 — Thu, 19 Jul 2012 05:00:38 +0000

Our extinct prehistoric cousins, the Neanderthals, may have spent less of their time living the rugged life of the hunter and more of it carrying out tedious domestic chores, a new study suggests.

Researchers investigated the causes of distinctive skeletal features that occur in Neanderthal remains. Compared with modern and most prehistoric Homo sapiens, Neanderthal skeletons have significantly overdeveloped right arms. In some cases, their upper arm bones are as much as 50% stronger on their right side than their left. By comparison, living humans display much lower levels of upper arm bone strength asymmetry at about 5-15%.

Biological anthropologists have previously argued that this was the result of right-handed Neanderthals using spears to hunt big game, which would have certainly been an activity critical to ensuring their survival in the variable climate of the Pleistocene epoch, from about 450,000 to 30,000 years ago.

̽��ֱ��new study suggests that Neanderthal skeletal asymmetry may have been the result of a less glamorous subsistence task. ̽��ֱ��paper, published in the journal PLOS One suggests that Neanderthals may have spent hours scraping animal hides using stone tools possibly for clothing production. That would have been an arduous and repetitive task, essential in the cold conditions in which they lived.

“ ̽��ֱ��asymmetry we see in the arms of Neanderthals is far more profound than anything we encounter in modern humans except some sportspeople, such as cricketers and tennis players”, Dr Colin Shaw, from the PAVE research group and the McDonald Institute for Archaeological Research at the ̽��ֱ�� of Cambridge, said.

“ ̽��ֱ��skeletal remains suggest that Neanderthals were doing something intense or repetitive, or both, that had a significant role in their lives. If it was hunting, it was taking up a great deal of their time. Not surprisingly, that theory has coloured our view of Neanderthal ‘the hunter’.”

“Our research moves away from that perspective. Hunting was an important part of the lives of Neanderthals. However, for much of their time Neanderthals might have been performing other tasks, such as preparing skins. If we are right, it changes our picture of the daily activities of Neanderthals.”

̽��ֱ��notion that the Neanderthal’s skeletal asymmetry might be the result of hunting became popular in the mid-1990s. ̽��ֱ��bones in question are the wrong cross-sectional shape to have developed as the result of repeatedly throwing spears, like a javelin. Experts have suggested, however, that they may have used spears two-handed and in an underarm motion, like a pool cue. Despite other convincing research, there had not been any tests of the musculature to examine this thesis, until now.

̽��ֱ��new study was carried out by a team of researchers from the Universities of Cambridge, Oxford and Penn State in the US. To measure the impact of repeated hide-scraping, and of a spear being used two-handed to kill game at close-quarters, the researchers carried out several tests in which groups of right-handed men were asked to carry out tasks replicating both activities.

̽��ֱ��impact on the upper arm was tested using a technique called electromyography, in which the electrical potential generated by muscles is measured during activity. ̽��ֱ��muscles analysed in this case were those at the shoulder and chest, which act as the primary movers of the humerus. Assessing their activity would provide a good indication of loads imposed upon the humerus (upper arm bone).

Surprisingly, they found that during two-handed spear thrusting tasks, the muscular activity was far higher in the left arm compared to the right. “It appears that because the left hand is the closest point of contact when the spear impacts the target,” said Shaw, “the reaction force is primarily countered by aspects of the musculoskeletal system on the left side of the body.”

By contrast, one-handed scraping tasks that simulated the processing of animal hides to be used as clothing required far more muscular activity on the right side of the body in precisely those areas which would lead to over-development of the upper-right arm. This suggests something other than hunting, and quite possibly the scraping of animal skins, was a task which occupied large amounts of the Neanderthals’ time, and influenced the unique morphology of their upper body.

̽��ֱ��idea that scraping animal hides was indeed a popular activity seems likely because Neanderthals would have required protective and warm clothing. One of the tools most commonly found with Neanderthal skeletal remains is the racloir, or ‘side-scraper’, a device used to scrape soft tissue from the underside of animal hides.

Although we have no way of knowing for sure how the Neanderthals made clothes, an educated guess can be made on the basis of ethnographic studies of traditional communities in places such as Ethiopia, British Columbia and Alaska, where animal hides are still prepared.

These studies have shown that processing animal skins is quite a laborious task, and even experienced individuals need about eight hours to scrape a single hide. Preparing several hides for each member of a community would have required exactly the sort of repetitious activity attested to by the overdeveloped right arms of Neanderthal skeletons.

̽��ֱ��researchers behind the new study admit that it can only go so far to explain the skeletal asymmetry. In ethnographic studies, for example, women rather than men are those who primarily prepare the animal hides. Insufficient numbers of female Neanderthal remains have been identified for a comparative study to be possible.

There is also the possibility that more Neanderthals than we think were left-handed. This seems unlikely, however. “We should always be tentative when making judgments about prehistory because any conclusions we draw are really inferences,” Shaw said. “About 90% of modern humans, however, are right-handed and that has been a dominant trend for at least 10,000 years. There is no obvious reason to suppose that Neanderthals were different.”

̽��ֱ��traditional image of Neanderthals as gritty people who spent most of their time out hunting might not be entirely accurate, according to a new study revealing that they may have had to devote hours to daily subsistence tasks instead.

If we are right, this changes our picture of the daily activities of Neanderthals.

Colin Shaw

Wikimedia Commons.

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