Diet disorder
What causes the mood swings of attention deficit hyperactivity disorder (1 April, p 8)? Consider the 7-year-old who is normally a charming boy 鈥� polite, attentive, fascinated with how things work and generally calm 鈥� and then without warning is bouncing off the walls, shouting at his mother and clearing the kitchen table with a single backhander. The cause is easy to see: a bad modern diet that is overloaded with sugars, additives and anything else that the food industry can get away with to maximise profit.
I fear the focus on a cure using a cocktail of drugs is always going to be the preferred option for researchers, as it might lead to funding and recognition. Simply telling people to eat more greens, to cut out the rubbish from the diet and not to poison their kids with sweeteners might be seen as too simple.
The editor writes:
鈥� Children can become hyperactive for many reasons, one of which is diet, but a child who is normally attentive is unlikely to have ADHD. This underlines the message of our article, which is that ADHD is a complex condition (see ) whose diagnosis should be the responsibility of a qualified psychiatrist or paediatrician through extensive behavioural observation in different contexts.
Accidental underdose?
Andy Coghlan suggested that a possible explanation for the tragic ill effects of TGN1412 might have been an accidental “overdose” (25 March, p 10). Has anyone considered the possibility that the investigators may have inadvertently “underdosed” the volunteers?
It was hoped that TGN1412 would work by binding to the CD28 receptor of regulatory T-cells and activating them to dampen down the immune response. But if it has a stronger affinity for the CD28 receptor of “conventional” T-cells than for that of regulatory T-cells, a low dose may be enough to stimulate the former but not to stimulate the protective regulatory T-cells, resulting in the disastrous effects seen. I note that the investigators administered just 0.2 per cent of the dose considered safe in animal experiments.
The same effect could appear if there were a subtle difference between the messenger systems that convey the message from the CD28 receptor into the regulatory and “conventional” T-cells.
For cod's sake
Contrary to Nick Palmer’s opinion, the culling of Canada’s harp seal pups is well justified, as it could allow the survival of the few remaining cod (25 March, p 22). Harp seals eat enormous quantities of fish, and are very wasteful. As pointed out in Mark Kurlansky’s book Cod, harp seals don’t like to deal with bones: they tear into the belly of the cod and leave the rest.
Cod can live for 20 to 30 years, and used to grow to well over 1.5 metres long, weighing 90 kilograms. Fully mature, they were relatively safe from seal predation, and spawned astronomical quantities of eggs. Because of overfishing, mature cod no longer exist. The larger remaining codlings are 2 to 3 years old and under 60 centimetres long. Since all the large cod have been fished out, these remaining bite-sized juvenile cod are the only hope for continuation of the species.
During the last seal-hunting ban, the harp seal population doubled. Culling is necessary to save the remaining cod.
Teaching evolution
Robin Holden wonders how good biology teachers could possibly teach creationism (1 April, p 24). He should come to south-east London, where I teach science and where there are many biology graduates who are creationists. Many, though not all, are from Christian parts of Africa or Asia.
I know of two local biology teachers who are not only creationists, but who believe literally in a seven-day creation a few thousand years ago, and I can think of at least three student teachers who have passed through our own department in recent years who are both biology graduates and creationists.
These people cannot teach creationism under the national curriculum (yet) but what they do in the classroom with the miserable little bit of Darwinism left in the syllabus I shudder to think. Many of my most able pupils are creationists, too. It is not just in America that the darkness is gathering.
From Norman McCanch
I am a rara avis among biology teachers, one whose specialisms are ecology and evolutionary biology. The vast majority of my biology graduate colleagues are essentially physiologists, biochemists and microbiologists and lack background knowledge and experience to do justice to the most neglected parts of biology in the curriculum, namely ecology and evolution.
Many cannot even name the trees, flowers and invertebrates inhabiting the school grounds and certainly cannot adequately interpret these complex subjects to young minds. These teachers are poorly prepared to deal with the sort of insidious questioning which accompanies the creationist view and have little more than a few textbook examples to refer to in response.
Canterbury, Kent, UK
Wrong priorities
Having just read your special on lunar science, I find myself horrified by the money being poured into projects that are unsustainable and irrelevant in comparison with the good that the money could do here on Earth (1 April, p 32). It is not only space science that is guilty: I often find myself wondering whether the returns in terms of benefits to humans or the planet can justify the resources put into projects such as particle colliders.
I do not presume to say what science is worthy of being pursued, but it seems obvious we have more critical problems to solve, notably improving people’s quality of life and minimising our impact on the planet. The amount of money that WHO projects, for example, require to tackle some of them is minute compared with NASA’s billions.
Space travel in its present form promotes unsustainability. Perhaps we need to re-examine the priorities of today’s science if we want to preserve our dreams of future possibilities.
Give me a child…
As a child’s brain develops, there are short periods during which the ability to process certain information, be it vision, sound or language, can be acquired. If the relevant window of opportunity is missed, the child’s ability to process that information will be lost or significantly hampered. Since the Pirah茫 children were not exposed to concepts such as numbers, colours or time when growing up, they have difficulties grasping such concepts later in life (18 March, p 44). It is a matter of exposure, not language or culture. Give me a Pirah茫 child, and I can use objects to train him to understand those concepts without altering his language or culture.
I stand by Chomsky’s theory of universal grammar, which is akin to our (almost) universal ability to understand the visual language of red, green, blue and white (but not infrared or ultraviolet). What we need is the right environment for inborn ability to develop to its potential. If our eyes were covered during the first couple of months after birth, we would never be able to read this sentence.
From Niki Edwards
The linguist Dan Everett suggests that the Pirah茫 are not given to “fretting about the future” and that they “live for the moment”. However, when they ask an absent Everett, via a tape recorder, to bring matches and bananas when he next visits them, are they not living beyond the moment?
Main Beach, Queensland, Australia
Culling mozzie larvae
John Balfour is concerned that rainwater storage tanks will breed mosquitoes (25 March, p 24). In my experience there is an easy solution. In Adelaide the public water supply is notorious for its high salt content and unpleasant taste, and many residents have a rainwater tank attached to the house to allow them to brew a decent beer or cup of tea. We moved to a house with a 5000-litre corrugated iron tank but I was discouraged by the presence of lively mosquito larvae in a typical jug of water.
I first attempted to remove them by adding a metal mesh filter to the tap. This worked but the water supply reduced to a trickle as the larvae clogged the filter, which needed cleaning every month or two.
Attempt 2 was a variation on the Australian outback practice of pouring a little kerosene into the tank. It floats on the surface and kills the larvae when they ascend and try to breathe. The prospect of adding aromatic hydrocarbons to my drinks did not appeal, so I tried vegetable oil. As the water level in the tank rose and fell, the oil accumulated as a gunge on the sides of the tank and became ineffective.
Attempt 3 was biological control. I added a couple of small fish to the tank and they worked perfectly for the couple of years we continued living in that house.
Anatarctic isolation
Your article describing the problems and training for astronauts going to Mars brought back memories (11 March, p 34). The situation describes exactly what I was told when I joined the forerunner of the British Antarctic Survey, back in 1958. We signed on for a two-season hitch, took about four months to get to base and four back. We could send and receive letters at a couple of places on the way down, after that once a year. Communication on base was via Port Stanley on the Falkland Islands with a telegram once a month.
On our base there were five men (no women in those days), who had to get along real well. Added to this was the danger of living in an inhospitable place. We had no psychological tests or preparation. The interviewer just looked me in the eye and said, “It can be rugged down there.”
At least we could go outside for a walk or skiing if the weather was reasonable and not blowing a blizzard. And scream if we wanted to. There was also the remote possibility of talking to people on the ham radio when we really needed, though this was impossible in winter.
Altogether a very interesting experience and very similar to going to Mars. Unfortunately now I’m a little too old!
Is farther older?
In the 25 March issue there seems to be a misrepresentation of the ages of galaxies (“Shady deals on galactic scale,” page 21). It states that cosmologists “compared the mass ratio of visible and dark matter in these [faraway] galaxies with the ratio in galaxies that are close by 鈥� and therefore older.”
Nearby and distant galaxies may well be the same age, but the visible-light images received from distant galaxies represent a time when the universe was “younger” compared with the visible-light images from closer galaxies.
Celestial pioneer
My article on the “celestial express” inadvertently omitted a key part of the history of low-energy pathways across the solar system (25 March, p 32). The foundations of the entire area were created in 1991 by Edward Belbruno of Princeton University, whose work was used to rescue the Japanese spacecraft Hiten and get it to the moon using such routes 鈥� the first time that this method was used. The mission established the technique’s practical advantages and convinced people that it really does work.
In 1994 Belbruno published the first paper describing the invariant manifold tubes for the lunar transfer, and his work was also used by ESA’s lunar spacecraft SMART1. He is the author of the only textbook on the topic: Capture Dynamics and Chaotic Motions in Celestial Mechanics, published by Princeton University Press and reviewed by Carl Murray in New 杏吧原创 (15 May 2004, p 48).
Raining algae
Now that Milton Wainwright and his colleagues have confirmed that the Indian “red rain” cells contain DNA, it seems most likely that they are algae, and as he suggests in his letter, are not in the least mysterious, despite the date it was published (1 April, p 12 and p 25).
Researchers in Kerala suggest that the red rain could be cells of a red-pigmented green alga, Trentepohlia, but there are other likely candidates. The green algal genus Haematococcus is a member of the motile order Volvocales which forms spores and resting-stage “palmella” structures, both enclosed by thick cell walls, and very similar to the pictures that you published. The cells are strongly red-coloured by the carotenoid pigment astaxanthin, formerly called haematochrome.
One species, Haematococcus pluvialis, occurs in ephemeral rain pools and its specific name means “of rain”. In arid environments, water or dust containing the cells may be picked up by mini-tornadoes, the usually acknowledged source of bizarre objects such as the froglets, snails, small fish and other creatures deposited in storm showers.
From Guy Cox, University of Sydney
Hazel Muir presents an electron micrograph and asks, “Does it look alien to you?” Having spent quite a lot of time over the past 30 years working on cyanobacteria, the answer has to be, “No, not at all.”
It looks very like a cyanobacterium (blue-green alga) of the genus Gloeocapsa or Gloeothece. In this case the red colour would come from c-phycoerythrin and there would also be absorption from chlorophyll. These both absorb strongly at wavelengths reasonably close to the reported figures. The “unusual” cell wall (or sheath) is quite typical of these genera and gives them amazing tolerance to drying: they can live just about anywhere. I have not, however, found any previous references to them living in clouds.
Sydney, Australia