Irradiation debate
As Dominic Dyer made clear in “Kill all known germs” (25 June, p 28), there is no evidence that certified organic products are more likely to be contaminated by Escherichia coli. All food is susceptible, and recent European Union research even shows less contamination in organic livestock.
The answer lies in controlling risks throughout the food chain. Consumer safety is the aim of all organic producers; growers and processors are independently inspected for organic certification, and must abide by strict hygiene guidelines and food safety laws.
There is no evidence that “lives will be saved” if organic standards allow irradiation. EU organic regulations do not allow it because it does not fit with organic principles, which state that processing should guarantee to maintain the integrity and vital qualities of the food. There is also a lack of long-term studies into potential health impacts.
In the UK, irradiation is only permitted for seven food categories. It is not allowed in dairy produce, as it changes the flavour, and in some fruits, because of tissue softening. Other adverse effects are possible: irradiation plant workers are at risk if safeguards are not followed, and irradiation of imported cat food in Australia has been banned after . It is also impossible to tell if maximum irradiation doses are exceeded.
As for the claim that organic food has higher levels of toxins as a result of not using fungicides, this has been disproved.
From Chris Smaje
Dyer bemoans the banning of food irradiation under organic standards. A degree of scepticism about new technologies is not necessarily unscientific.
But more important is the inherent vulnerability to infection of produce in a system, organic or otherwise, based on long supply chains of food in which irradiation becomes an answer to the problems this can create. Dyer uses science as a cipher for high-tech and piecemeal solutions to the problems created by this unwieldy chain.
We need a wider debate about what kind of food system we want.
Frome, Somerset, UK
Yeast harmony
Some crucial steps in the journey of single-celled yeasts to multicellular form occur very quickly, far quicker than the 350 generations over 60 days noted (25 June, p 10).
Even the 90 minutes it takes for a new cell to bud off is a long time compared with the 5 minutes or so needed to establish a conversation between two yeast cells lying close together. Within this time, spontaneous rhythms of energy production . Soon this dynamic state can spread through a population of many thousands.
Thus a rhythm within a single organism leads to cell-cell communication, a conversation and eventually to the coherence of a crowd.
Social and altruistic behaviour appears even in this “simplest” of eukaryotes. Irrespective of whether yeasts were once multicellular organisms or not, they clearly prefer to form a choir than sing solo.
Childhood advice
Anyone working with children needs to heed Jon Ronson’s article on misdiagnosis of childhood bipolar disorder (4 June, p 44).
Parents have lost their intuition about normal behaviour: children are meant to be childish. The reason those aged under 7 cannot hold two emotions or two thoughts at a time is that they have not yet undergone the cognitive shift described by psychologist Jean Piaget, in which cognitive ability becomes more sophisticated. A child cannot remember not to hit their sister when they are mad, because at that moment they have forgotten they also love their sister.
The prefrontal cortex, the centre for mixing feelings, is under construction until after adolescence, and many adults still have black-or-white thinking.
While medication may help a few with attention-deficit disorder, parents must be made aware of the personal cost: it numbs all feelings. Since you require feelings to learn and adapt, these children will also be unable to mature. Thus a pattern is established where impulsive behaviour is treated with further medication, preventing maturation.
Code breaker
The idea of using Google Search for sending hidden messages (18 June, p 26) was less than convincing for several reasons.
You would need to be in possession of a codebook, which would be a double liability. Being caught with a codebook is bad enough, but if it falls into the wrong hands, the whole channel is compromised. It would also be necessary to infect computers with a keylogger of sorts, to track which keys you strike. This might be a problem as most public computers don’t let users install anything. The keylogger is evidence if traces are left on the computer.
As well as all these kludges, the method will only work if there is considerable traffic between the sender and receiver, which the article alludes to. Verdict: two thumbs down.
Divine digits
I thought it was eccentric to have a favourite number until I read your interview with Alex Bellos (25 June, p 29). Mine is 23, because it is the temperature in degrees Celsius at which I am most comfortable, my favourite Mozart piano concerto and the first prime number made up of consecutive digits.
From Carol Herzenberg
Bellos talks about favourite numbers and what people say about them. Using number 8 as an example, he reports several types of responses, including that people like 8 because it has a beautiful shape. This reminded me of the joke: What did the 0 say to the 8? “Nice belt! “
Chicago, Illinois, US
Spider tales
The diving-bell spider’s use of a web bubble as a gill came as no surprise (18 June, p 20). I refer you to Gerald Durrell’s 1969 book Birds, Beasts and Relatives.
I quote:
Bird brains
The reference to crows sharing information on humans regarded as a threat (2 July, p 5) reminded me of noted zoologist Konrad Lorenz’s 1966 book On Aggression.
Since reading it in 1971, I have never forgotten his description of crows using a specific call to alert other crows to the approach of a person who had threatened or harmed them in the past. That tiny brain demonstrating such communication and facial recognition skills makes the relatively large human brain look remarkably inefficient.
Cetacean translation
Using a cryptographic approach to crack foreign languages is a nice, fresh approach to machine translation (18 June, p 23).
It might also offer intriguing possibilities for decoding another form of communication. Researchers working with bottlenose and spotted dolphins have identified some elements of their “language”, such as their signature whistles. In addition, their echolocation sounds are recognised. However, most of the potential meaning of the chirping and buzzing they make remains elusive.
Is it possible that dolphins could communicate with one another about a specific object by producing a set of sounds corresponding to an “echolocation picture”? It would be interesting to know if the deciphering software could look for similarities between patterns of acoustic signals that dolphins produce in social situations, and their patterns of echolocation reflecting from objects of interest in their environment.
Sideways look
Looking at the diagrams with a hidden message in the article on understanding risk (25 June, p 31) reminded me of how sonar operators used sonar printouts to detect the presence of submarines.
At first sight, the printouts looked as if someone had shaken pepper and salt over the grey paper and produced a meaningless pattern. However, if one looked almost horizontally along the paper the frequency lines produced by the submarines’ propellers appeared. Once they had been detected it was impossible not to see them when looking at the paper at right angles.
This technique proved just as effective in solving the puzzle in your article.
Double trouble
I hesitated to write, but in the interests of science here goes. In “Lopsided love” (18 June, p 42) Menno Schilthuizen mentioned the anatomical oddity of the left testicle hanging lower in about 2 out of 3 men.
I had noticed this asymmetry about myself, and wondered why it occurred. I realised that when sitting, for example, there is not a lot of room down there, and the testicles are pushed together. Thanks to the asymmetry, they slide smoothly into a vertical arrangement. Had they been symmetrical, there might be a nasty squash. The asymmetry makes sitting more comfortable. Mystery solved?
What goes up鈥�
With reference to the cover line “Sky’s the limit: gliders that never have to land” (25 June), in aviation the sky is not the limit. The ground, however, definitely is.
For the record
鈥he diagram in “Creature contacts” (28 May, p 32) gave the impression that dogs originated in East Africa 32,000 years ago. While it is generally thought they originated there, the 32,000-year-old fossil mentioned in the text was found in Belgium.