Melt down

One joy of following scientific progress is seeing it connect threads of knowledge into a tapestry revealing a picture of a previously unknown scene.

In recent years, evidence has emerged from researchers in South Africa that when we exercise, our brain makes us feel tired, not our muscles. Clearly, muscles are limited in their ability to keep running or cycling. But apparently we have a mechanism in the brain which prevents us reaching the point where we might do damage.

The latest is the unmasking of a protein, Interleukin-six—the messenger which spreads the news that we’re tired. When runners in a 10 kilometre race were injected with Interleukin-six before running, they felt tired and their times were slowed by about a minute, compared with runners injected with a placebo. This provides an explanation for the phenomenon of the ‘second wind’. If the brain recognises that the end of a race is near, it may well ease up on the tiredness message, allowing a dash for the line.

There are also potential clinical applications of this work. This work may provide us with a handle on that most slippery of conditions, Chronic Fatigue Syndrome (CFS). It opens up the possibility that CFS may not be due to lack of energy at all, but perhaps to a misfiring of the system in the brain. We might even be able to treat it using drugs which block the messenger. The dark side? Shooting the messenger might enhance athletic performance, but at a risk of severe muscular damage.

The best example these days of scientific connections can be traced to global warming. One issue is the spread of infectious diseases. French researchers recently studied over 300 diseases, and found their distribution was mostly linked to climate. As the climate warms, pathogens previously restricted to the tropics are now moving into temperate parts of the world. In the past five years, North America has been invaded by the potentially deadly West Nile virus, while mosquito-borne diseases such as Dengue Fever and Ross River virus are spreading in Australia. It’s the same for diseases affecting our crops and herds.

More unusually, as reported in New Scientist magazine, this last northern summer has been one of the worst ever for rockfalls in the European Alps. Fifty people have died. Nearly 100 climbers were rescued from the Matterhorn in Switzerland when part of the normal climbing route collapsed. Massive rock formations in the Italian Dolomites have come crashing down. One suggestion, supported by computer modelling and experimentation, is that global warming is thawing the permafrost in temperate zone mountains and destabilising the rock faces—the mountains are literally melting.

The average temperature rise of 0.7 degrees Celsius over the past 25 years has caused a decrease in rice yields of about ten per cent. The reason seems to be that the warming is uneven—the rise in night temperatures being about three times that of day temperatures. This means that rice plants expend more energy at night, leaving less for photosynthesis during the day. Plummeting yields of the world’s most widely-eaten crop is not good news.

One impact of climate change is its ability to paralyse the conservative federal governments of the US and Australia. They seem to think that any move away from profligate use of fossil fuels will destroy their economies. Archimedes believes that curbing greenhouse gas emissions is the only way to retain some control of our own destiny, as opposed to becoming mere observers of the planet’s most extensive experiment.  

Tim Thwaites is a freelance science writer.



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