Chewing the fat
Marion Nestle’s article on the scrapping of Denmark’s fat tax rightly highlights the scale of the public-health challenge posed by obesity (24 November, p 28).Clearly, a broad range of evidence-based interventions are essential if we are to reverse population weight gain.
As Nestle mentioned, the Danish government decided, after only a year, to abolish its tax on foods containing more than 2.3 per cent saturated fat. This suggests that the government recognised that the tax does not work.
Instead of imposing arbitrary taxes on hard-pressed consumers, we have to empower people to make healthier choices. Food and drink manufacturers in the UK are playing their part by introducing clear labelling, developing healthier choices and changing recipes to reduce the saturated fat, salt and energy content of many brands.
They are also working with the government, health organisations and others to encourage appropriate lifestyle changes.
No single food or nutrient can cause obesity, unless consumed excessively and for a prolonged period. Restriction on the production and marketing of “unhealthy” foods will always face the same conundrum – there are no good or bad foods, just good or bad diets.
Restrictions on portion size might be a better option. Smaller servings would discourage people from overeating and address the distorted perception about what constitutes a suitable portion.
Huddersfield, West Yorkshire, UK
Nestle may think that the statement “governments… have a role in addressing the health problems caused by obesity” is beyond dispute, but she is wrong. It seems to be based on the idea that governments are responsible for such healthcare costs. Why should that be so? People need to take responsibility for their own poor decisions.
Casselberry, Florida, US
Feeling the buzz
After 40 years as a beekeeper, I saw your article on extraordinary intelligence in honeybees as getting close to a truth, but not quite reaching it (24 November, p 42). In particular, it touched on Karl von Frisch’s description of the “famous ‘waggle dance’, the steps of which signal the direction and distance to nearby flowers”.
However, I believe the dance is more likely to be a precursor that summons other bees by vibrating the comb in a dark hive. The bee then gives directions to forage by some other means. I suspect this other means, a bee language if you like, is based on antenna touching, which bees do constantly in pairs and in groups.
If a language does exist in honeybees it would explain much about their ability to organise themselves.
• There was about the significance of the dance, but the consensus now is that it does transmit information (19 September 2009, p 40).
Significant steps
Further to your coverage of the use of stem cells to recover mobility in dogs with damaged spines (24 November, p 7), it is important to make clear that this is not a cure for spinal cord injury in humans. But it is the most encouraging advance for some years, and is a significant step on the road towards a human cure.
The innovative process in this research uses olfactory “ensheathing” cells taken from the dog’s own nasal lining. In the nose, these cells repair nerve fibres, and they can do the same job when transplanted to the spinal cord. This shows that the beneficial effects previously reported in rodents can be produced in other species and systems. That is encouraging for application in human injuries.
From a clinical perspective, the benefits are still limited at this stage. This procedure has enabled an injured dog to step with its hind legs, but restoring the higher functions lost in human spinal cord injury – such as hand manoeuvrability, bladder function and temperature regulation – is more complicated and still a long way away.
Your report on the treatment for semi-paralysed canines talked of a placebo for dogs. Surely not.
Sunbury-on-Thames, Middlesex, UK
Figure of speech
Feedback has poked gentle fun at reports describing area in terms of football pitches or Wales, lengths as multiples of a London bus, and so on, but now you’re doing it in the story on tapping the electrical potential of ear cells (17 November, p 18).
The voltage in the cochlea is said to be “a fraction of that generated by an AA battery”. Readers are grown-up enough to cope with numbers and SI units.
• The range is 70 to 100 millivolts in the mammalian cochlea.
Arms and man
Contrary to Stuart Leslie’s letter (10 November, p 32), in my article on the role of deadly weapons in human cultural evolution (13 October, p 46), I quoted theorists who suggest, not that early humans had strength-based hierarchies similar to chimpanzees, but the opposite: that they had reversed that hierarchy and become more egalitarian. And that this in part had to do with their ability to throw lethal weapons.
And while it is true that we are equally related to chimpanzees and bonobos, the social organisation of the two species is not as different as Leslie suggests. The consensus is that the higher levels of female solidarity shown by bonobos evolved after the two species split – and serve to temper an underlying male dominance hierarchy similar to that found in chimps.
Evolutionary Earth
The oxygen-rich environment in which we live was created by the rise of photosynthesising organisms, triggering vast climate change and an opportunity for biological diversification. So why should we limit human-caused environmental change (17 November, p 34)?
Surely we are only doing what comes naturally, and behaving otherwise is simply to deny the chance for other life forms to evolve as the environment shifts.
So, are we really destroying the climate or are we simply playing a walk-on part in the blockbuster of constant change that has always taken place on the planet?
Abortion law
The interview with Lisa Harris on Savita Halappanavar’s death after allegedly being refused an abortion in Ireland (24 November, p 29) prompted memories of dark days in 1950s Australia.
At the time abortion was illegal and I was a trainee nurse at a Melbourne hospital. We treated women who had had abortions induced in all manner of dangerous ways. The risk of infection was high. Lifting the ban saved the lives of many women.
Evidence, at last?
So Ran Hassin and colleagues have provided evidence that complex linguistic and arithmetical operations can be performed unconsciously (17 November, p 14). What is striking is that this was the founding insight of the cognitive revolution decades ago.
For example, in his 1957 book Syntactic Structures, US linguist Noam Chomsky argued for the existence of unconscious rule-following in the construction of sentences. These are not the familiar rules from grammar lessons, but surprising rules involving, for example, transformations and derivational steps. Chomsky has also argued that mathematical ability is an application of this unconscious computational system.
The recent experimental results are valuable, but they hardly presage a sea change. If anything, they may serve to defend traditional cognitive science from some of its critics.
Still life
Following your look at how autobiographical memory develops (6 October, p 36), I would aver that all my very early memories are static images.
Knowing that my father returned from the war in early 1946 when I was just over 3 years old, and that we immediately left the area where I was living with my mother and grandparents, I can safely assert that the many memories of these events and of the people and places that I’ve never seen since must predate my 4th birthday.
However, they are all simply a series of single snapshots, whereas memories of, say, 10 years later, are most decidedly movie-like.
How big?
North Korea, according to Keith Bowers (24 November, p 38), occupies an area around the size of Pennsylvania. Hmm. I could locate North Korea easily on a map, but Pennsylvania?
Yorkshire food chain
The slightly revolting idea of using maggots to recycle human waste more directly back into the food chain has been known about for years (24 November, p 10). It has been taken further, according to the traditional song On Ilkla Moor Baht’at.
This describes the dangers of walking on the Yorkshire moors without a hat. Dying of cold is followed by burial and consumption by worms, which are eaten by ducks. The ducks end up on our dinner plates and the circle is complete. A neat system that does not appear to have worried anyone.
Heaven sent
I read your article on apparent seasonal changes in radioactive decay rates (17 November, p 42). If I understand Jere Jenkins and Ephraim Fischbach’s paper correctly, they have detected a statistically significant but tiny decrease in the rate of beta decay of manganese-54, as correlated with solar flare activity.
“Aha!” say the young-Earth creationists, decay rates just ain’t what scientists say they are. Using the same decay discrepancy figure, they will claim that the conventionally accepted 4.54-billion-year age of Earth should be adjusted down to – wait for it – 6000 years.