Features

A lot of the time, the tables, figures and graphs included in scientific papers can be pretty impenetrable for those outside that particular area of research. But just occasionally there are figures that can stand alone from a paper, illustrating clearly what the raw data show.

This figure comes close to that ideal. It is very clear that the overall death rate among adults aged 15–54 in Russia is much higher than in Western Europe. The reason? Alcohol.

Most, if not all, of the four-fold difference in risk of death now seen in this age range can be put down to alcohol, and to a lesser extent tobacco.

And while overall death rates in Western Europe have been decreasing, largely as people stop smoking, Russian death rates have fluctuated wildly as alcohol use has altered in the face of political and economic change.

The proportion of deaths in adulthood that can be put down to alcohol in Russia is staggering. A study published in The Lancet and led by the Clinical Trial Service Unit [CTSU] at Oxford University and the Russian Cancer Research Centre in Moscow has found that over half of deaths among people in their 20s, 30s and 40s in Russia are caused by alcohol. This can be from alcohol poisoning, accidents, violence, or through diseases strongly related to alcohol, such as TB, pneumonia, pancreatitis or liver disease.

Professor Sir Richard Peto, who led the statistical analysis of the data at CTSU, said: ‘If current Russian death rates continue, then about 5 per cent of all young women and 2 per cent of all young men will die before age 55 years from the direct or indirect effects of drinking.’

The graph shows Russian death rates dropping when alcohol consumption fell by a quarter in 1985 under President Gorbachev’s 1985–8 anti-alcohol laws. They doubled between 1988 and 1994 when they reached a peak before the Russian economy collapsed. Since then, the death rates have varied but remained high.

There is some hope in these observations. As Professor Peto says, ‘This shows that when people who are at high risk of death from alcohol do change their habits, they immediately avoid most of the risk.’ 

Final preparations are underway for our 3 July event for visitors from the World Conference of Science Journalists (WCSJ 2009).

As our previous post explains the event gives international and UK journalists the chance to meet some of Oxford's top scientists and enjoy drinks and food in the lovely riverside surroundings of Magdalen College.

We've been bowled over by the response from all quarters and the final guest list is bursting at the seams with the sort of people who make Oxford University such an exciting place to do/write about science.

As previously reported Professor Sir Richard Peto, Professor Lionel Tarassenko, Professor Fred Taylor and Dr Ian Goldin are among those attending but the guest list now also includes Professor Sir David Weatherall, Professor Valerie Beral, and Professor Steve Davies - and we also hope to see Lord May.

I'd like to give a special mention to the friends of OxSciBlog who will be there: these include engineer and roboticist Dr Paul Newman, and podcast contributors Professor Irene Tracey and Professor Frances Ashcroft.

Thanks in advance to everyone helping to make this happen. 

It's easy to think of mass extinctions only in terms of the impact on animal species but of course plants suffered too.

Stephen Hesselbo of Oxford's Department of Earth Sciences reports in this week's Science on his research studying fossils to see how plants fared in a major extinction event 200 million years ago.

I asked him about what these plant fossils can tell us about extinctions, biodiversity and climate change.

OxSciBlog: Why are these Greenland fossils of particular interest to those studying climate/biodiversity?
Stephen Hesselbo: The East Greenland fossil plant beds represent a uniquely detailed record of floral change across one of the 'big five' mass extinctions that characterize the history of life over the last 500 million years - that which occurred at the Triassic-Jurassic boundary, 200 million years ago.

The plant beds, which represent a warm temperate community, have been known about for about a hundred years, but have previously been worked on principally from the point of view of taxonomy and evolutionary relationships.

This new study takes advantage of the fact that a series of plant beds leading up to the mass extinction horizon were laid down under similar conditions on the banks of rivers in flood - changes in plant assemblages can therefore be interpreted in terms of changing ecosystems rather than vagaries of plant preservation.

A series of expeditions have shipped back more than a tonne of fossil material and so the statistics of the present study are based on large numbers.

OSB: What do they tell us about interactions between CO2 levels and plant life in the Triassic?
SH: Previous work on the density of stomata [the holes through which CO2 diffuses to the site of photosynthesis] on the fossil leaves  has indicated increases in CO2 over the Triassic-Jurassic boundary interval.  These are estimated to have risen from a starting value of about 600 ppm to a maximum of about 1800 ppm through the extinction event.

One effect of the flux of CO2 into the atmosphere is to leave a record in the carbon-isotope ratios of organic matter formed at the time.

Although the Triassic-Jurassic extinction was dramatic amongst animals, hitherto the effects on plants appear to have been much less intense.  However, the present study provides evidence for very marked collapse in ecosystem diversity in the run up to the extinction.

OSB: What do we think may have caused the sort of dramatic loss of biodiversity seen in this period?
SH: The Triassic-Jurassic boundary coincides with a period of volcanism on a massive scale - think Iceland but scaled up a hundred to a thousand times.  This happened as the super-continent Pangaea broke up (initiating formation of the Atlantic ocean in the process).

As well as directly contributing gasses such as CO2 and SO2 to the atmosphere, it is likely that molten rock baked older deposits of organic-rich sediments and salt to create large fluxes of CO2 and SO2 and other gases such as halocarbons. Other mass extinctions similarly coincided with periods of hugely enhanced volcanic activity.

OSB: Can we draw any lessons from this period about how rising CO2 emissions may affect plant/animal life in the future?
SH: To a certain extent yes - the present day flux rates for carbon are higher than anything that was likely at the Triassic-Jurassic boundary, but the total amount of carbon emitted is considerably less, so far.

Further complications are the unknown quantities and effects of the the additional gases produced during the mass extinction event.

Nevertheless, these so called 'flood basalt eruption' episodes do represent a natural pre-run of exactly the kind of release of fossil carbon, sulphur and other elements that we are currently subjecting the planet to.

OSB: How might further research in this area help us to better understand the impacts of climate change?
SH: This study shows how plant ecosystems responded to environmental change in the interval leading up to a mass extinction. Further work should tackle also the recovery interval, after the peak of the mass extinction, as ecosystems returned to normality.

Additionally we need to better constrain the changes in atmospheric carbon-dioxide that went alongside floral change, and also document similar changes that must have been occurring on different parts of the ancient Earth at the same time.

Finally an improved 'age model' (i.e. chronology of events) would be very useful. With these pieces of information we will be in a better position to describe the deterioration of plant ecosystems in response to greenhouse-gas forcing.

Professor Stephen Hesselbo is based at Oxford University's Department of Earth Sciences. The research was conducted with co-authors Jennifer McElwain of University College Dublin and Peter Wagner of the Smithsonian Institution.

Collecting guano halfway up a cliff may not be everyone's idea of fun but it has led to the discovery of the oldest nest of a bird of prey ever recorded.

Kurt Burnham, a DPhil student at Oxford University's Department of Zoology, was part of a team that collected 20 guano samples from 13 different gyrfalcon nest sites in cliffs in central-west and northwest Greenland.

Radiocarbon dating of these samples has found that one of the nests has been in continuous use for the last 2740-2360 years with three other nests likely to be over 1000 years old. The team report their findings in the journal Ibis. 

The nests themselves are little more than depressions or scrapes in rock ledges but the guano deposits reveal the long history of the birds' occupation.

'When analysing multiple samples from the same nest it was also possible to detect changes over time in the type of prey consumed, very likely an indicator of changes in the prey composition in the area,' Kurt told us.

'This study provides both information on the likely initial colonization of these areas by gyrfalcons in addition to probable paleoenvironmental conditions at the time and patterns of glacial retreat. ' 

So what makes the falcons return year after year? 

Kurt told BBC News Online: 'Something, be it nest ledge depth, or the amount of cliff overhang above the nest, is so attractive at these locations that gyrfalcons are re-using them for thousands of years.'

But, as he explains, this attachment makes them vulnerable to climate change.

'As a result of a warming and ameliorating climate other bird species, such as peregrine falcons, are moving further north.'

'As peregrine populations continue to increase in density they will likely use more and more of these traditional gyrfalcon nests, forcing gyrfalcons to find alternate locations to nest in which may not offer the same amount of protection from the harsh Arctic environment in Greenland.'

More in this Telegraph article. 

Scientists who saved the Large Blue butterfly are now turning their attention to some of the other 10,000 insect species that depend on ants for their survival.

Like the Large Blue these insects – ranging from butterflies and moths to beetles and hoverflies – all rely on ants in one way or another for food and protection and are known to be particularly vulnerable to the sort of environmental changes associated with climate change.

'Only seven or eight of the 10,000 or so insect species that we know depend on ants have been studied at all,' Jeremy Thomas of Oxford University’s Department of Zoology told us.

'Whilst the work done at Oxford and elsewhere on the Large Blue and its relationship with ants saved one species there are thousands more that are living on the edge and, if we don’t act quickly, could disappear from Britain’s meadows, woods and heathland.'

The insects in question range from beautiful butterflies such as the Silver Studded Blue [Plebejus argus], which co-habits with the Black garden ant [Lasius niger], to a hoverfly you might mistake for a bee [Microdon mutabilis], which lives off a type of wood ant [Formica lemani], to a beetle [Lomechusa] which specialises in getting ants to feed and protect it.

It's amazing to think that so many insects have found a way to infiltrate ant society and get a 'free ride' from their more socially-inclined neighbours. The nest parasite Lomechusa is a fascinating beast with a cuckoo-like lifestyle, the difference being this beetle never grows up and continues to trick ants into caring for it even as an adult.

But it's this relationship with ants that makes these insects particularly sensitive to small changes in habitat which, whilst not affecting them directly, can have a devastating impact if they affect the ant populations they depend on.

Jeremy explains: 'In the case of the Large Blue butterfly and the red ants [Myrmica sabuleti] it was a combination of less grazing by both human livestock and wild animals that caused the ants' 'microhabitat' to become overgrown, so that ant populations fell and there weren’t enough ants to nurture the next generation of Large Blues.'

'The worry is that these are just the sort of changes we can expect to see as a result of climate change.'

The researchers intend to study the impact human activity is having on 11 endangered insect species and the ants that support them. They will then use this information to predict how future changes in climate and land use will affect these populations and work out what can be done to mitigate any harmful effects.

Jeremy adds: 'our previous work has shown that if we can understand the complex relationships between these species and what they need to survive then we can take action to save them.'

'When you think that the number of insect species that rely on ants is twice the number of all mammal species in the world then it seems if we are serious about preserving biodiversity then we need to do all we can to save such endangered insects.'

Professor Jeremy Thomas is based at Oxford's Department of Zoology.