Analysis of the teeth of a 2-million-year-old hominin known as Australopithecus sediba, a relative of modern humans, reveals that they ate leaves, fruits and bark. The results, reported in Nature this week, suggest that these early hominins lived in a woodland environment.
This press release contains:
· Summaries of newsworthy papers:
Biology: Cooling theories on whether dinosaurs were cold-blooded
Heart disease: How one heart attack can lead to another
Solar physics: Twisters take the heat from the Sun
Planetary science: Atmospheres on other planets
Biology: A strong model of muscle evolution
Environment: Climate change and vegetation shifts
Nuclear physics: Charting the nuclear landscape
And finally... The tooth about early hominin diets
· Geographical listing of authors
 Biology: Cooling theories on whether dinosaurs were cold-blooded (AOP; N&V)
A key argument used to support theories that dinosaurs were not warm-blooded is debunked in this week’s Nature. Lines of paused growth on bones were thought to be indicative of cold-bloodedness and have been seen on dinosaur bones, leading to suggestions that dinosaurs cannot have been warm-blooded. This study provides evidence these markers do not mean that an animal is cold-blooded.
Meike Köhler and colleagues settle the issue of the significance of arrested bone growth with a comprehensive study of large ruminant mammals, which are unquestionably warm-blooded. Lines of arrested growth (LAGs), indicating seasonal slowdown or cessation of growth, have been observed in the bones of reptiles and amphibians and correlate with changes in body temperature. Warm-blooded creatures are assumed to grow continuously due to their ability to maintain a constant body temperature, and evidence that some birds and mammals have LAGs seems to have been regarded as exceptional. Köhler’s team find LAGs on the bones of reindeer and antelope, among other large warm-blooded animals. They conclude that LAGs cannot be used to distinguish whether creatures, such as dinosaurs, are cold-blooded or warm-blooded.
Meike Köhler (Autonomous University of Barcelona, Bellaterra, Spain)
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Kevin Padian (University of California,Berkeley, CA, USA) N&V author
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 Heart disease: How one heart attack can lead to another (AOP)
Heart attacks and strokes accelerate hardening of the arteries, known as atherosclerosis, which in turn can increase the risk of recurrent events. The processes underlying this vicious cycle are uncovered in a mouse study in this week’s Nature, which shows that heart attacks cause the release of inflammatory cells that aggravate atherosclerotic lesions. Treatments that target precursors of these offending cells may help to mitigate disease progression.
Although the likelihood of survival following a heart attack is nearly 90%, recurrent events are common and carry a high risk of death. Matthias Nahrendorf and colleagues demonstrate that heart attacks in mice activate a pathway involving the nervous system, the bone marrow and the spleen. This pathway enhances the production of cells called monocytes, which intensify chronic hardening of the arteries. Retrospective analysis of a clinical trial reveals that prior beta-blocker therapy is associated with decreased circulating monocytes after a heart attack. The authors conclude that interventions that interrupt the supply of monocytes could attenuate atherosclerosis and may improve long-term patient outcomes.
Matthias Nahrendorf (Massachusetts General Hospital, Boston, MA, USA)
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 Solar physics: Twisters take the heat from the Sun (pp 505-508; N&V)
Magnetic 'tornadoes' on the Sun are thought to act as energy channels that transfer heat from its surface to its atmosphere. These observations, reported in Nature this week, provide a plausible mechanism with which to explain why the outer atmosphere of the Sun is substantially hotter than its surface.
Heating the outer layers of the solar atmosphere (the corona) requires a large amount of energy, but how this energy is transferred and dissipated has remained a puzzle. Sven Wedemeyer-Böhm and colleagues detect swirling magnetic structures, resembling super-tornadoes, which reach from the Sun's surface (the photosphere) into the upper solar atmosphere. They propose that the formation of these swirls is related to the convection of heat from the photosphere to the corona, and validate this hypothesis using three-dimensional numerical simulations. The authors conclude that this process is probably able to transfer the energy needed to heat the upper solar atmosphere.
Sven Wedemeyer-Böhm (University of Oslo, Norway)
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Steven Bradshaw (William Marsh Rice University, Houston, TX, USA) N&V author
 Planetary science: Atmospheres on other planets (pp 502-504)
Detection of carbon monoxide in the atmosphere of a non-transiting planet, an achievement that has previously been limited to transiting planets, is reported in Nature this week. The finding enables the measurement of the mass and orbital inclination of t Boötis b, one of the first exoplanets to be discovered. Such characteristics are normally detected when one planet transits in front of its parent star, and have been hard to constrain for t Boötis b.
Since its discovery, measurements of the orbital inclination of tBoötis b have been announced and subsequently refuted. Ignas Snellen and colleagues observed carbon monoxide absorption in the spectrum of tBoötis b using high-resolution spectroscopy measurements from a telescope in Chile. From this signature, the authors calculate that the planet is orbiting at an inclination of around 44.5 degrees, and is around 5.95 times the mass of Jupiter. They conclude that their ground-based high-resolution spectroscopy technique could be used to detect atmospheres on other exoplanets.
Ignas Snellen (Leiden University, The Netherlands)
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 Biology: A strong model of muscle evolution (AOP)
Similarly structured muscle cells seem to have evolved separately in different animal groups, according to research published in Nature this week. The work shows that proteins integral to muscle function predate muscle cells, and the data reveal that such independent evolution can be achieved through the acquisition of different sets of proteins by different animal groups.
Fibrous (striated) muscles in bilaterian animals such as humans and insects share structural similarities to those in non-bilaterian creatures, such as jellyfish, and it is these similarities that have supported the view that striated muscles share a common evolutionary origin. However, Ulrich Technau and colleagues now show that animals in the phylum Cnidaria (which includes jellyfish) lack many components of striated muscle cells seen in animals with bilateral symmetry (such as humans). They find that a core set of muscle proteins was present in unicellular animals before the origin of muscles themselves. The authors report that other proteins were added to this core protein set during the independent evolution of striated muscles in different animal groups, resulting in strikingly similar ultrastructures.
Ulrich Technau (University of Vienna, Austria)
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 Environment: Climate change and vegetation shifts (AOP)
Large areas of vegetation are likely to shift abruptly to alternative states as a result of climate change, according to simulations reported in Nature this week. However, differences in the timing of these shifts will dampen their overall effect on the Earth system. In particular, increased atmospheric carbon dioxide is shown to encourage shifts to vegetation types with larger leaf areas and/or woody-plant dominance.
The effects of climate change on plant ecosystems are likely to be complex, as increased atmospheric carbon dioxide is expected to favour trees, whereas increased temperature will favour grasses. Steven Higgins and Simon Scheiter model the effects of climate change on tropical grasslands, savannah and forest ecosystems in Africa from 1850 to 2100. They show that it is possible that a considerable proportion of the African continent will shift to more woody vegetation states, although continental changes will be spread over a longer time period. The authors note that their findings indicate that atmospheric carbon dioxide has been, and will be, a major factor shaping vegetation change.
Steven I. Higgins (Goethe Universität, Frankfurt am Main, Germany)
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 Nuclear physics: Charting the nuclear landscape (pp 509-512)
Uncertainties regarding the number of protons and neutrons that can be bound in a nucleus are quantified in this week’s Nature. These findings shed light on the fundamental problem of understanding nuclear stability, and allow estimates of the limits of nuclear binding. Understanding the stability of nuclides (or isotopes) is important because they govern stellar processes that create the matter around us.
Of the several thousand nuclides thought to exist, only around 3,000 have been observed (either natural or synthetic), and only 288 are considered to be stable. These nuclear species have been mapped on a ‘chart of nuclides’ – the periodic table of the nuclear physics world. The boundaries marking the end of nuclear binding are known as drip lines (where the addition of more protons or neutrons leads to a highly unstable nuclide). For heavier elements, these are based on uncertain theoretical predictions. Witold Nazarewicz and colleagues quantify this uncertainty using a technique known as nuclear density functional theory. In doing so, they predict that the number of bound nuclides with atomic numbers between 2 and 120 is around 7,000.
Witold Nazarewicz (University of Tennessee, Knoxville, TN, USA)
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 And finally... The tooth about early hominin diets (AOP)
Analysis of the teeth of a 2-million-year-old hominin known as Australopithecus sediba, a relative of modern humans, reveals that they ate leaves, fruits and bark. The results, reported in Nature this week, suggest that these early hominins lived in a woodland environment. This conclusion is in contrast to previously described diets of other early hominin species that suggested an open savannah habitat.
Two A. sedibaskeletons discovered in South Africa in 2008 have provided an opportunity to study early hominin species. Amanda Henry and co-workers determine the diet of these hominins by looking at patterns of dental wear and analysing tiny plant fragments on their teeth. The authors also consider carbon-isotope data derived from the skeletons, which can indicate the types of carbon source that were eaten. Notably, bark and woody tissues were found in the teeth of the two individuals; this has not been documented previously for hominins. The findings indicate that A. sediba had a diet that is somewhat unexpected compared with the diets of similarly aged early African hominins.
Amanda G. Henry (Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany)
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ALSO IN THIS ISSUE:
 Activation of remote meta-C–H bonds assisted by an end-on template (pp 518-522; N&V)
 Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight (pp 513-517)
 Direct and Highly Regioselective and Enantioselective Allylation of β-Diketones
 Biophysical Mechanism of T Cell Receptor Triggering in a Reconstituted System
GEOGRAPHICAL LISTING OF AUTHORS:
The following list of places refers to the whereabouts of authors on the papers numbered in this release. For example, London: 4 - this means that on paper number four, there will be at least one author affiliated to an institute or company in London. The listing may be for an author's main affiliation, or for a place where they are working temporarily. Please see the PDF of the paper for full details.
Toronto: 2, 4
Frankfurt am Main: 6
Heidelberg: 2, 10
München: 5, 10
Uppsala: 3, 10
UNITED STATES OF AMERICA
La Jolla: 9
Menlo Park: 10
San Francisco: 12
Chevy Chase: 2
New York: 11
Oak Ridge: 7
College Station: 8
From North America and Canada
Neda Afsarmanesh, Nature New York
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From Japan, Korea, China, Singapore and Taiwan
Eiji Matsuda, Nature Tokyo
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From the UK
Rebecca Walton, Nature London
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