Horse sense
It is no surprise that it is “value ranges” of processed meat products that are being identified as containing horsemeat, sparking public concern and official investigation (16 February, p 6). And perhaps it is not surprising that this is being seen in products that should contain beef 鈥� a more expensive meat than, say, chicken.
These observations suggest that there is a shortage of beef products at a price suitable for value-range processed meat, despite the need to find a commercial home for all the parts of the beef carcass. This may be linked to last year’s European Commission that “desinewed meat” 鈥� flesh recovered from the bones of carcasses 鈥� should be labelled “mechanically separated meat”.
Retailers are pushing down prices to meet the needs of cash-strapped consumers. The low-grade beef available for processed products may now be just too expensive.
You mention testing horsemeat for the painkiller phenylbutazone or “bute”, which is banned from the food chain. But drugs like anabolic steroids, diazepam and chloramphenicol are used on horses too.
Chloramphenicol is an antibiotic that carries a small risk of aplastic anaemia, the disorder also associated with bute. It too is banned from the food chain.
Brighouse, West Yorkshire, UK
Nervous connotation
Your story on how the brain stores and organises words gave a fascinating glimpse into the neurological underpinning of category formation (5 January, p 10). It reminded me of the distinction, emphasised in old-fashioned books on logic, between the denotation and connotation of words.
The denotation of the word “salmon”, for example, is the set of all salmon, which is smaller than the set of all fish. Its connotation is the set of criteria that describe what a salmon is. Generally speaking, the smaller the denotation set, the larger is the connotation. So describing “salmon” requires more criteria than does “fish”.
Jack Gallant’s results are exactly what one would expect if information about classes of objects such as fish and dogs were organised in the brain on the basis of their connotation.
Adding successive criteria to the connotation of a set would give more and more specific subsets. If the neuronal filters described in your article add criteria in this way, they would be most efficiently placed near the neural representations of the larger categories.
Fair incentive
Brian Farrington suggests that people who do not want wind power on their doorstep should be offered an incentive to accept it (2 February, p 28). I suggest that for equity those affected by thermal power stations should be offered an incentive, backdated to when the facility was built. While we are at it, how about those affected by overhead power lines?
Or we could just accept that we have our part to play as citizens.
Prime after prime
You report the discovery of the largest known prime number in the Great Internet Mersenne Prime Search (9 February, p 7). Mersenne primes are based on the formula 2p 鈥� 1, where p is a prime number. Let’s call the result L. Logically then, 2L 鈥� 1 must also be a prime, and it must be considerably larger. We should thus be able to create an infinite list of increasingly large primes simply by inserting each back into the Mersenne formula. Is there something wrong with the formula, or is the problem one of finding a separate way of checking that the result is indeed prime?
鈥� Although French monk Marin Mersenne sought a formula for all primes, it is not reliable in that sense. For example, 11 is prime, but 211 鈥� 1 = 2047 = 23脳89. Whether the number of Mersenne primes is finite is unknown.
Institution in need
I am shocked at the possibility that the UK’s Royal Institution will close its doors (26 January, p 27). As a retired professor of physics, whose membership of the institution extends back decades, I am drawn to visit it when in London. Its history of active research and educational outreach to a very wide audience is unrivalled by any other scientific organisation.
Won’t some individual, group, foundation or government body step up to keep it open?
Colonial genocide
Stephen Corry writes of the poor outcomes for tribal people when nation states are imposed on their way of life (9 February, p 32). Settlers encountering inconvenient tribalists are likely to wipe them out completely. There was a lot of this in North America, including intentionally distributing blankets from smallpox victims to Native Americans. The final stages of genocide, in California, were almost entirely private. We must also assume that tribes wiped out earlier tribes, possibly beginning with the Neanderthals.
Nation states have also been involved, but they can protect as well as harm. The 18th-century British government tried to stop settlers going too far westwards, and Native Americans in what became Canada did not fare as badly as those farther south.
Squirrelled away
Thank you for the cute photograph of a lonely red squirrel in Aperture (9 February, p 26). The text, however, raised some questions, saying the grey squirrel has “outcompeted the native reds for food and habitat” over most areas of the UK during the last century.
But how much is grey competition to blame for the red’s decline? Have the red’s poor adaptability and resistance to anthropogenic stresses and to disease been the main causes? If no greys had been introduced a century ago, what are the chances that there would in fact be few squirrels of any colour in most parts of Britain?
In an era of climate change, species everywhere are impelled to move to new habitats, where new ecological balances will need to be struck. The presumption of guilt against “invasive species” needs to be replaced by case-by-case evaluation, and where applicable by facilitating new adaptations and introducing wildlife bridges and corridors.
Right is wrong
There are indeed liberals and progressives who have unscientific beliefs, as Alex Berezow and Hank Campbell point out (2 February, p 24). But in political parties with left leanings, these unscientific beliefs are relegated to the fringe, whereas, they are in the mainstream of the US Republican party.
Maybe the fact, as reported in your editorial in the same issue (p 3), that only 9 per cent of scientists identify themselves as conservative, with even fewer seeing science as a conservative field, should be considered further. Why is it that the majority of scientists are liberal? Maybe because a majority of conservatives, at least in the US, are anti-science.
Sleep on it
I’d like to shed more light on the possible purposes of sleep and dreaming (2 February, p 30). Throughout my active life I have always solved my most intractable problems, mostly technical, while asleep 鈥� provided that I first prime myself by going through the history of the problem in a logical sequence. My most creative thinking has come about this way.
The number of people who claim they dream in colour rose once films and TV stopped being in black and white. David Robson also mentions visual elements predominating over sounds and smells. I was born in 1935, and so I grew up with radio, not TV, and my dreams are still full of the spoken word.
For example, very early in the morning on the UK’s election day in 1992, I heard the BBC announce the result. It was some time before I was awake enough to realise this was a dream, since the polling stations hadn’t opened.
The next morning, the BBC announced the result just as I’d dreamed it: a nightmare come true, heralding five more years of Conservative rule.
Wooler, Northumberland, UK
Font of some wisdom
Your look at how fonts can mess with our minds highlighted the fuss over Comic Sans being used in a presentation announcing the possible discovery of the Higgs boson at CERN (22/29 December, p 68). In a technical context, lack of precision can easily lead to misunderstanding or even danger. Comic Sans is one of the few fonts that clearly distinguish between capital “I”, lower case “l”, and the number “1”. Maybe Comic Sans is not such a bad choice for scientists after all.
Where there's muck
Your article on fertilising crops with human sewage omitted one key point (16 February, p 48). Plants have a highly efficient water-treatment system of their own. In the outer layer of the roots 鈥� the cortex 鈥� water travels largely through and between the cell walls, which form a very fine physical filter. At the inner boundary of the cortex 鈥� the endodermis 鈥� the cell walls are impermeable and all water and nutrients must pass through the cells themselves, where any foreign material that has penetrated that far can be destroyed in enzyme-filled compartments called lysosomes. It is most unlikely that infectious agents will get through to the water-conducting tissues.
Plants evolved these defences for their own protection, but they also protect any animal that eats the leaves and fruit.
The key to safe use of sewage, therefore, is to ensure that it only contacts the roots. Simple, low-tech solutions can achieve this. The converse is also true 鈥� using contaminated water in spray irrigation is a recipe for trouble.
From Christopher Jessop
Further to Fred Pearce’s excellent piece on sewage as a resource, one wonders how much potential soil conditioner the world’s vacuum cleaners “harvest” annually, only for it to go to landfill.
Marloes, Pembrokeshire, UK
For the record
鈥� We are irate at having said that an Aristotle quote was from Rhetoric, rather than Nicomachean Ethics, in our look at the possible upsides of anger (9 February, p 48)