Human evolution: Last Neanderthals were unexpectedly tenacious

Nature VOL.443. Summaries of newsworthy papers include Why summer heatwaves could be more common, Changes in the Sun’s luminosity are not responsible for climate change, How oxygen gangs up under pressure, Shaking a quantum bridge, Galaxy formation kicks off

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VOL.443 NO.7108 DATED 14 SEPTEMBER 2006

This press release contains:

· Summaries of newsworthy papers:

* Human evolution: Last Neanderthals were unexpectedly tenacious
* Climate change: Why summer heatwaves could be more common
* Climate: Changes in the Sun’s luminosity are not responsible for climate change
* Chemistry: How oxygen gangs up under pressure
* Quantum physics: Shaking a quantum bridge
* And finally… Galaxy formation kicks off

· Mention of papers to be published at the same time with the same embargo

· Geographical listing of authors

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[1] Human evolution: Last Neanderthals were unexpectedly tenacious (AOP; N&V)
DOI: 10.1038/nature05195

***This paper will be published electronically on Nature's website on 13 September at 1800 London time / 1300 US Eastern time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 14 September, but at a later date.***

The Neanderthals survived in Europe for several millennia after the arrival of modern humans, according to excavations from what seems to have been their last refuge, at the very southern tip of the continent. The discovery suggests that they may not have immediately succumbed after the encroachment of modern humans but hung in there for longer than expected, in isolated refuges.

Neanderthals (Homo neanderthalensis) may have survived in Gibraltar, a rocky outcrop off the Spanish coast, until 28,000 years ago, and perhaps as recently as 24,000 years ago, report Clive Finlayson and his colleagues online this week in Nature. Modern humans arrived in western Europe at least 32,000 years ago, suggesting that the two hominin species shared the landscape for several thousand years.

The new findings come from Gorham's Cave, in which stone tools were first discovered more than 50 years ago. Dating of more recently uncovered artefacts, including a series of hearth places all created at the same location within the cave, now show just how long-lasting was the Neanderthal settlement. People living there would have had access to diverse plants and animals, sandy plains, woodlands, wetlands and coastline — an environmental richness that probably helped the Neanderthals to persist for so long.

CONTACT

Clive Finlayson (The Gibraltar Museum, Gibraltar)
Tel: +350 74289; E-mail: [email protected]

Eric Delson (American Museum of Natural History, New York, NY, USA)
Tel: + 1 212 769 5992; E-mail: [email protected]

Please note that a Press Conference relating to this research is being held under embargo on:

Wednesday 13 September 1500 hours London time (BST) / 1600 hours local time Gibraltar
John Mackintosh Hall, Main Street, Gibraltar (site of the ‘Calpe 2006’ conference)

Contact at the Gibraltar Museum for media enquiries:

Darrien Ramos (The Gibraltar Museum, Gibraltar)
Tel: +350 49161; E-mail: [email protected]

[2] Climate change: Why summer heatwaves could be more common (pp 205-209)

Computer models of the effects of global warming on future climate predict that summer temperatures in Europe and other temperate regions are going to become more variable, perhaps creating more heatwaves like the one in 2003. Using climate simulations, Sonia Seneviratne and colleagues have pinpointed one of the reasons why this may be the case.

Their study, published in this week’s Nature, shows that the increase in summertime variability predicted in central and eastern Europe arises mainly because of the way the land surface and the atmosphere interact. In particular, changes in temperature lead to changes in the amount of moisture evaporating from soils, which in turn affects the temperature. And as a region’s climate alters, the type of vegetation it supports may change, which in turn affects the strength of the feedback between soil moisture and temperature.

These feedbacks between the land and atmosphere are quite complex; in some regions, the predicted increase in summer temperature variability is much smaller in simulations that don’t take such feedbacks into account.

The researchers say that the effect of land–atmosphere interactions is particularly strong in central and eastern Europe because rising global temperatures are predicted to lead to a northwards shift of climate zones, so that the transition from dry to wet climates will occur in this region rather than, as at present, in more southerly latitudes. Transitional zones of this sort are especially sensitive to feedback processes between soil and air, the researchers say.

CONTACT

Sonia Seneviratne (ETH, Swiss Federal Institute of Technology, Zurich, Switzerland)
Tel: +41 44 632 80 76; E-mail: [email protected]

[3] Climate: Changes in the Sun’s luminosity are not responsible for climate change (pp 161-166)

Reviewing the evidence of the past millennium, Peter Foukal, Henk Spruit and colleagues argue in Nature this week that changes in the sun's total energy output, or luminosity is unlikely to have played a significant part in climate change at least since the seventeenth century, and probably over the past several millennia.

The amount of energy emitted by the sun - total solar irradiance (TSI) - rises and falls by a little under 0.1 per cent in step with the sunspot cycle. Might longer-term changes in TSI, possibly driven by variations in solar activity, have caused at least part of the trends in global temperatures observed in recent decades and inferred over past centuries? Recent advances in understanding why TSI varies make this unlikely. The team addresses this by extrapolating TSI back to the year 1000, reconstructing the resulting global temperature changes using computer models, and then comparing these with the records of actual temperature change inferred from palaeoclimate data. TSI in historical times can be estimated from measurements of the amounts of the isotope beryllium-10 in the geological record, because this form of beryllium is produced in the atmosphere in nuclear reactions that depend on solar activity - and hence TSI.

If these estimated changes in past TSI are the only source of global temperature change, then the computer simulations show that they are too small to explain the observed climatic variations. "Overall," the researchers say, "we can find no evidence for solar luminosity variations of sufficient amplitude to drive significant climate variations on centennial, millennial and even million-year timescales." they say there are other, more complex processes involving the sun's variable outputs of ultraviolet light and magnetized gases that could potentially alter the earth's climate. Whether these processes could have played any part in observed climate changes remains to be determined.

CONTACT

Henk Spruit (Max-Planck Institute, Garching, Germany)
Tel: +49 89 3299 3220; E-mail: [email protected]

Peter Foukal (Heliophysics Inc, Nahant, MA, USA)
Tel: +1 781 581 0712; E-mail: [email protected]

Tom Wigley (University Corporation for Atmospheric Research, Boulder, CO, USA)
E-mail: [email protected]

Claus Fröhlich (World Radiation Centre, Davos, Switzerland)
E-mail: [email protected]

[4] Chemistry: How oxygen gangs up under pressure (pp 201-204; N&V)

The structure of an enigmatic phase of solid oxygen is revealed in Nature this week. Solid oxygen forms six distinct crystallographic phases, and variously transforms between insulating, metallic, magnetic and superconducting states. But the structure of the dark-red epsilon phase — formed under high-pressure conditions — has remained unknown since its discovery, almost thirty years ago.

Malcom McMahon and colleagues now present their detailed X-ray diffraction observations on the epsilon phase of solid oxygen, collected in the high-pressure region 13–18 GPa. They show that oxygen molecules (O2) gang up in distinct groups of four, to form rhombohedral molecular units, with each unit probably held together by weak chemical bonds.

These rhomb-shaped O8 units are quite different from the long-sought, eight-membered oxygen rings, which would be an analogue of the well-known sulphur S8 molecule. Furthermore, computational models do not predict the observed epsilon phase structure, which challenges our understanding of dense oxygen.

CONTACT

Malcom McMahon (University of Edinburgh, UK)
Tel: +44 131 650 5956; E-mail: [email protected]

Burkhard Militzer (Lawrence Livermore National Lab, Livermore, CA, USA)
Tel: +1 925 422 4515; E-mail: [email protected] N&V author

Russell J Hemley (Carnegie Institution, Washington DC, USA)
Tel: +1 202 478 8951; E-mail: [email protected] N&V author

[5] Quantum physics: Shaking a quantum bridge (pp 193-196; N&V)

According to quantum theory, you can't make a measurement on an object without perturbing it. The act of observation delivers a series of ‘prods’ to the object being observed. This is called quantum back-action, and it is seen as a nuisance that hinders highly precise measurements. Keith Schwab and team demonstrate in Nature this week that back-action can be put to good use, as a means of cooling down quantum objects to extremely low temperatures.

Heisenberg's uncertainty principle states that certain pairs of quantities describing the state of a quantum object, such as momentum and position, can't be measured simultaneously with complete precision. Narrowing the constraints on one of them makes the other fuzzier. It is as if, by attempting to determine the precise position of the object, we give it kicks that render the momentum unclear.

Schwab and colleagues carried out measurements of this sort on a tiny beam of silicon nitride just a few tens of nanometres wide, called a nanoresonator. Changes in the position of the beam alter the electrical conductivity of a nearby electronic device called a superconducting single-electron transistor (SSET), which allows this position to be determined. But making that measurement 'shakes' the nanoresonator, because of quantum back-action.

Yet when the voltage applied to the SSET is set at a particular value, corresponding to a quantized energy state of the electrons passing through it, the vibrations of the nanoresonator decrease — in effect, it is cooled down, as the SSET becomes an absorber rather than a source of heat. This effect might be used to produce ultracold states of nanoscale mechanical devices, the researchers say.

CONTACT

Keith Schwab (Cornell University, Ithaca, NY, USA)
Tel: +1 607 255 9962; E-mail: [email protected]

Michael Roukes (California Institute of Technology, Pasadena, CA, USA)
Tel: +1 626 395 2916; E-mail: [email protected]

[6] & [7] And finally… Galaxy formation kicks off (pp 189-192; N&V)

Galaxies were being formed when the Universe was only around 6% of its present age, suggest two papers in Nature this week, though big galaxies were rare.

Masanori Iye and colleagues report the discovery of the most distant spectroscopically confirmed galaxy. Rychard J. Bouwens and Garth D. Illingworth look somewhat further back in time, and report that luminous galaxies were quite rare at around 700 million years after the Big Bang.

Their results provide support to the idea that galaxies were built up hierarchically from much smaller pieces during the period from around 300 to 900 million years after the Big Bang.

CONTACT

Masanori Iye (National Astronomical Observatory, Tokyo, Japan)
Tel: +81 422 34 3520; E-mail: [email protected] Author paper [6]

Rychard J. Bouwens (University of California, Santa Cruz, CA, USA)
Tel: +1 831 459 5276; E-mail: [email protected] Author paper [7]

Richard McMahon (University of Cambridge, UK)
Tel: +44 1223 337 548; E-mail: [email protected] N&V author

ALSO IN THIS ISSUE…

[8] Oscillatory dependence of current-driven magnetic domain wall motion on current pulse length (pp 197-200)

[9] An intron with a constitutive transport element is retained in a Tap messenger RNA (pp 234-237)

[10] Policing of oncogene activity by p53 (p159)

ADVANCE ONLINE PUBLICATION

***This paper will be published electronically on Nature's website on 13 September at 1800 London time / 1300 US Eastern time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 14 September, but at a later date.***

[11] Stoichiometry and turnover in single, functioning membrane protein complexes
DOI: 10.1038/nature05135

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.

CANADA

Montreal: 5

Ottawa: 4

Toronto: 1

FRANCE

Bruyeres-le-Chatel: 4

GERMANY

Garching: 3

GIBRALTAR
Gibraltar: 1

JAPAN

Kyoto: 6

Tokyo: 6

Yokosuka: 1

SPAIN

Cadiz: 1

El Puerto Santa Maria: 1

Granada: 1

Huelva: 1

Madrid: 10

Murcia: 1

Tarragona: 1

Villamartin: 1

SWITZERLAND

Davos: 3

Zurich: 2

UNITED KINGDOM

Bournemouth: 1

Cambridge: 1

Egham: 1

Edinburgh: 4

London: 1

Nottingham: 5

Oxford: 1

UNITED STATES OF AMERICA
California

San Jose: 8

Santa Cruz: 7

Stanford: 8

Colorado

Boulder: 3

Hawaii

Hilo: 6
Maryland

Baltimore: 6

College Park: 5
Massachusetts

Nahant: 3
New Hampshire

Hanover: 5

Virginia

Charlottesville: 9

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From Japan, Korea, China, Singapore and Taiwan

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Published: 13 Sep 2006

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