Friday, February 5, 2010

LOST ROMAN LAW CODE DISCOVERED IN LONDON

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Part of an ancient Roman law code previously thought to have been lost forever has been discovered by researchers at UCL's Department of History. Simon Corcoran and Benet Salway made the breakthrough after piecing together 17 fragments of previously incomprehensible parchment. The fragments were being studied at UCL as part of the Arts & Humanities Research Council-funded "Projet Volterra" – a ten year study of Roman law in its full social, legal and political context.

Corcoran and Salway found that the text belonged to the Codex Gregorianus, or Gregorian Code, a collection of laws by emperors from Hadrian (AD 117-138) to Diocletian (AD 284-305), which was published circa AD 300. Little was known about the codex's original form and there were, until now, no known copies in existence.

"The fragments bear the text of a Latin work in a clear calligraphic script, perhaps dating as far back as AD 400," said Dr Salway. "It uses a number of abbreviations characteristic of legal texts and the presence of writing on both sides of the fragments indicates that they belong to a page or pages from a late antique codex book - rather than a scroll or a lawyer's loose-leaf notes.

"The fragments contain a collection of responses by a series of Roman emperors to questions on legal matters submitted by members of the public," continued Dr Salway. "The responses are arranged chronologically and grouped into thematic chapters under highlighted headings, with corrections and readers' annotations between the lines. The notes show that this particular copy received intensive use."

The surviving fragments belong to sections on appeal procedures and the statute of limitations on an as yet unidentified matter. The content is consistent with what was already known about the Gregorian Code from quotations of it in other documents, but the fragments also contain new material that has not been seen in modern times.

"These fragments are the first direct evidence of the original version of the Gregorian Code," said Dr Corcoran. "Our preliminary study confirms that it was the pioneer of a long tradition that has extended down into the modern era and it is ultimately from the title of this work, and its companion volume the Codex Hermogenianus, that we use the term 'code' in the sense of 'legal rulings'."

This particular manuscript may originate from Constantinople (modern Istanbul) and it is hoped that further work on the script and on the ancient annotations will illuminate more of its history.

(Photo: UCL)

University College London

IS THE HOBBIT'S BRAIN UNFEASIBLY SMALL?

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Homo floresiensis, a pygmy-sized small-brained hominin popularly known as 'the Hobbit' was discovered five years ago, but controversy continues over whether the small brain is actually due to a pathological condition. How can its tiny brain size be explained? Researchers writing in the open access journal BMC Biology have tackled this question in the context of a comprehensive assessment of the evolution of brain and body size throughout the larger primate family.

Nick Mundy and Stephen Montgomery, from the Department of Zoology at Cambridge University, UK, and colleagues from Durham University used previously published data from living and extinct species to reconstruct the pattern of brain and body mass evolution in primates. According to Nick Mundy, "Our results provide robust confirmation for the suggestion that strong evolutionary trends have governed the expansion of the primate brain. In contrast, body size evolution has not tended to increase in primates, implying brain and body mass have been subject to separate selection pressures and supporting the findings of previous studies in other taxonomic groups that these two highly correlated traits can show differences in their patterns of evolution".

Brain expansion began early in primate evolution and has occurred in all major groups, suggesting a strong selective advantage to increased brainpower in most primate lineages. Despite this overall trend, however, Mundy and his colleagues have identified several branches/lineages within each major group that have shown decreasing brain and body mass as they evolve, for example in marmosets and mouse lemurs. According to Mundy, "We find that, under reasonable assumptions, the reduction in brain size during the evolution of Homo floresiensis is not unusual in comparison to these other primates. Along with other recent studies on the effects of 'island dwarfism' in other mammals, these results support the hypothesis that the small brain of Homo floresiensis was adapted to local ecological conditions on Flores."

(Photo: Professor Peter Brown, University of New England)

BioMed Central

WHY HUMANS OUTLIVE APES

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The same evolutionary genetic advantages that have helped increase human lifespans also make us uniquely susceptible to diseases of aging such as cancer, heart disease and dementia, reveals a study to be published in a special PNAS collection on "Evolution in Health and Medicine" on Tuesday, Jan. 26.

Comparing the life spans of humans with other primates, Caleb Finch, ARCO & William F. Kieschnick Professor in the Neurobiology of Aging in the USC Davis School of Gerontology, explains that slight differences in DNA sequencing in humans have enabled us to better respond to infection and inflammation, the leading cause of mortality in wild chimpanzees and in early human populations with limited access to modern medicine.

Specifically, humans have evolved what Finch calls "a meat-adaptive gene" that has increased the human lifespan by regulating the effects of meat-rich diets. ApoE3 is unique to humans and is a variant of the cholesterol transporting gene, apolipoprotein E, which regulates inflammation and many aspects of aging in the brain and arteries.

"Over time, ingestion of red meat, particularly raw meat infected with parasites in the era before cooking, stimulates chronic inflammation that leads to some of the common diseases of aging," Finch said.

However, another expression of apolipoprotein E in humans -- the minor allele, apoE4 -- can increase the risk of heart disease and Alzheimer's disease by several-fold, Finch explained. ApoE4 carriers have higher totals of blood cholesterol, more oxidized blood lipids and higher rates of early onset coronary heart disease and Alzheimer's disease.

"The chimpanzee apoE functions more like the "good" apoE3, which contributes to low levels of heart disease and Alzheimer's," Finch said. Chimpanzees in captivity have unusually low levels of heart disease and Alzheimer-like changes during aging when compared to humans.

Finch hypothesizes that the expression of ApoE4 in humans could be the result of the "antagonistic pleiotropy theory" of aging, in which genes selected to fight diseases in early life have adverse affects in later life.

"ApoeE may be a prototype for other genes that enabled the huge changes in human lifespan, as well as brain size, despite our very unape-like meat-rich diets," Finch said. "Drugs being developed to alter activities of apoE4 may also enhance lifespan of apoE4 carriers."

In spite of their genetic similarity to humans, chimpanzees and great apes have maximum lifespans that rarely exceed 50 years. Even in high-mortality modern hunter-forager populations, human life expectancy at birth is still twice that of wild chimpanzees.

University of Southern California

EVERYBODY LAUGHS, EVERYBODY CRIES: RESEARCHERS IDENTIFY UNIVERSAL EMOTIONS

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Everybody shares the vast majority of their genetic makeup with each other, meaning that most of our physical characteristics are similar. We all share other attributes, too, such as having complex systems of communication to convey our thoughts, feelings and the intentions of those around us, and we are all able to express a wide range of emotions through language, sounds, facial expressions and posture. However, the way that we communicate is not always the same – for example, people from different cultures may not understand the same words and phrases or body language.

In an attempt to find out if certain emotions are universal, researchers led by Professor Sophie Scott from UCL (University College London) have studied whether the sounds associated with emotions such as happiness, anger, fear, sadness, disgust and surprise are shared amongst different cultures. The results of their study, funded by the Wellcome Trust, Economic and Social Research Council, University of London Central Research Fund and UCL, are published today in the Proceedings of the National Academy of Sciences. They provide further evidence that such emotions form a set of basic, evolved functions that are shared by all humans.

Dr Disa Sauter, studied people from Britain and from the Himba, a group of over 20,000 people living in small settlements in northern Namibia as part of her PhD research at UCL. In the very remote settlements, where the data for the present study were collected, the individuals live completely traditional lives, with no electricity, running water, formal education, or any contact with people from other groups.

Participants in the study listened to a short story based around a particular emotion, for example, how a person is very sad because a relative of theirs had died recently. At the end of the story they heard two sounds – such as crying and of laughter – and were asked to identify which of the two sounds reflected the emotion being expressed in the story. The British group heard sounds from the Himba and vice versa.

"People from both groups seemed to find the basic emotions – anger, fear, disgust, amusement, sadness and surprise – the most easily recognisable," says Professor Scott, a Wellcome Trust Senior Research Fellow. "This suggests that these emotions – and their vocalisations – are similar across all human cultures."

The findings support previous research which showed that facial expressions of these basic emotions are recognised across a wide range of cultures. Despite the considerable variation in human facial musculature, the facial muscles that are essential to produce the basic emotions are constant across individuals, suggesting that specific facial muscle structures have likely evolved to allow individuals to produce universally recognisable emotional expressions.

One positive sound was particularly well recognised by both groups of participants: laughter. Listeners from both cultures agreed that laughter signified amusement, exemplified as the feeling of being tickled.

"Tickling makes everyone laugh – and not just humans," says Dr Disa Sauter, who tested the Himba and English participants. "We see this happen in other primates such as chimpanzees, as well as other mammals. This suggests that laughter has deep evolutionary roots, possibly originating as part of playful communication between young infants and mothers.

"Our study supports the idea that laughter is universally associated with being tickled and reflects the feeling of enjoyment of physical play."

Previous studies have shown that smiling is universally recognised as a signal of happiness, raising the possibility that laughter is the auditory equivalent of smiles, both communicating a state of enjoyment. However, explains Professor Scott, it is possible that laughter and smiles are in fact quite different types of signals, with smiles functioning as a signal of generally positive social intent, whereas laughter may be a more specific emotional signal, originating in play.

Not all positive sounds were easily recognisable to both cultures, however. Some, such as the sound of pleasure or achievement appear not to be shared across cultures, but are instead specific to a particular group or region. The researchers believe this may be due to the function of positive emotions, which facilitate social cohesion between group members. Such bonding behaviour may be restricted to in-group members with whom social connections are built and maintained. However, it may not be desirable to share such signals with individuals who are not members of one's own cultural group.

(Photo: Wellcome Trust)

Wellcome Trust

MONARCH BUTTERFLIES REVEAL A NOVEL WAY IN WHICH ANIMALS SENSE THE EARTH'S MAGNETIC FIELD

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Building on prior investigation into the biological mechanisms through which monarch butterflies are able to migrate up to 2,000 miles from eastern North America to a particular forest in Mexico each year, neurobiologists at the University of Massachusetts Medical School (UMMS) have linked two related photoreceptor proteins found in butterflies to animal navigation using the Earth's magnetic field.

The work by Steven Reppert, MD, professor and chair of neurobiology at UMMS; Robert Gegear, PhD, research assistant professor of neurobiology; Lauren Foley, BS; and Amy Casselman, PhD, is described in the paper, "Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism," posted on-line in the journal Nature January 24.

The research team used fruit flies engineered to lack their own Cryptochrome (Cry1) molecule, a UV/blue-light photoreceptor already known to be involved in the insects' light-dependent magnetic sense. By inserting into those deficient flies butterfly Cry1, a homolog of the fly protein, or the related butterfly protein Cry2, the researchers found that either form can restore the flies' magnetic sense in a light-dependent manner, illustrating a role for both Cry types in magnetoreception. "Because the butterfly Cry2 protein is closely related to the one in vertebrates, like that found in birds which use the Earth's magnetic field to aid migration," states Dr. Reppert, "the finding provides the first genetic evidence that a vertebrate-like Cry can function as a magnetoreceptor."

An interesting feature of the team's work disproved a widely held view about how these proteins can chemically sense a magnetic field. "These findings suggest that there is an unknown photochemical mechanism that the Crys use instead," says Dr. Gegear, lead author on the paper, "one that we are hotly pursuing."

One of the most exciting aspects of the work was showing that each of the two forms of butterfly Cry have the molecular capability to sense magnetic fields. Reppert's group is now developing behavioral assays to show that monarchs can actually use geomagnetic fields during their spectacular fall migration. "We believe we are on the trail of an important directional cue for migrating monarchs," states Reppert, "in addition to their well-defined use of a sun compass."

Reppert, who is also the Higgins Family Professor of Neuroscience at UMMS, has been a pioneering force in the effort to understand monarch butterfly navigation and migration. Earlier this year, he and colleagues demonstrated that a key mechanism of the sun compass that helps steer the butterflies to their ultimate destination resides not in the insects' brains, as previously thought, but in their antennae, a surprising discovery that provided an entirely new perspective of the antenna's role in insect migration.

University of Massachusetts Medical School

HUMAN RUNNING SPEEDS OF 35 TO 40 MPH MAY BE BIOLOGICALLY POSSIBLE

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Jamaican sprinter Usain Bolt's record-setting performances have unleashed a wave of interest in the ultimate limits to human running speed. A new study published in the Journal of Applied Physiology offers intriguing insights into the biology and perhaps even the future of human running speed.

The newly published evidence identifies the critical variable imposing the biological limit to running speed, and offers an enticing view of how the biological limits might be pushed back beyond the nearly 28 miles per hour speeds achieved by Bolt to speeds of perhaps 35 or even 40 miles per hour.

The new paper, "The biological limits to running speed are imposed from the ground up," was authored by Peter Weyand of Southern Methodist University; Rosalind Sandell and Danille Prime, both formerly of Rice University; and Matthew Bundle of the University of Wyoming.

"The prevailing view that speed is limited by the force with which the limbs can strike the running surface is an eminently reasonable one," said Weyand, associate professor of applied physiology and biomechanics at SMU in Dallas.

"If one considers that elite sprinters can apply peak forces of 800 to 1,000 pounds with a single limb during each sprinting step, it's easy to believe that runners are probably operating at or near the force limits of their muscles and limbs," he said. "However, our new data clearly show that this is not the case. Despite how large the running forces can be, we found that the limbs are capable of applying much greater ground forces than those present during top-speed forward running."

In contrast to a force limit, what the researchers found was that the critical biological limit is imposed by time -– specifically, the very brief periods of time available to apply force to the ground while sprinting. In elite sprinters, foot-ground contact times are less than one-tenth of one second, and peak ground forces occur within less than one-twentieth of one second of the first instant of foot-ground contact.

The researchers took advantage of several experimental tools to arrive at the new conclusions. They used a high-speed treadmill capable of attaining speeds greater than 40 miles per hour and of acquiring precise measurements of the forces applied to the surface with each footfall. They also had subjects' perform at high speeds in different gaits. In addition to completing traditional top-speed forward running tests, subjects hopped on one leg and ran backward to their fastest possible speeds on the treadmill.

The unconventional tests were strategically selected to test the prevailing beliefs about mechanical factors that limit human running speeds –- specifically, the idea that the speed limit is imposed by how forcefully a runner's limbs can strike the ground.

However, the researchers found that the ground forces applied while hopping on one leg at top speed exceeded those applied during top-speed forward running by 30 percent or more, and that the forces generated by the active muscles within the limb were roughly 1.5 to 2 times greater in the one-legged hopping gait.

The time limit conclusion was supported by the agreement of the minimum foot-ground contact times observed during top-speed backward and forward running. Although top backward vs. forward speeds were substantially slower, as expected, the minimum periods of foot-ground contact at top backward and forward speeds were essentially identical.

According to Matthew Bundle, an assistant professor of biomechanics at the University of Wyoming, "The very close agreement in the briefest periods of foot-ground contact at top speed in these two very different gaits points to a biological limit on how quickly the active muscle fibers can generate the forces necessary to get the runner back up off the ground during each step."

The researchers said the new work shows that running speed limits are set by the contractile speed limits of the muscle fibers themselves, with fiber contractile speeds setting the limit on how quickly the runner's limb can apply force to the running surface.

"Our simple projections indicate that muscle contractile speeds that would allow for maximal or near-maximal forces would permit running speeds of 35 to 40 miles per hour and conceivably faster," Bundle said.

Southern Methodist University

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