Just a pile of rubble
Stuart Clark suggests that planetoids form by the same process that makes dust bunnies under your bed (23 July, p 28). Sad as it might sound, I have spent some time observing dust bunnies. My conclusion is that they cannot form without some form of filamentous material: textile residues, hair, even spiderweb filaments. These seem unlikely in interplanetary space.
Another way to aggregate solid particles is by adding moisture. A water “glue” could work at the surface of solid particles with friction heating, but that, I believe, requires the existence of a dense disc of dust. This is the type that quickly collapses into clumps and planets according to the rival “disc instability” model. I doubt whether the Neptune trojans are more than rubble piles with little or no structural cohesion.
At least it's a theory
If educational institutions were required to label books “Evolution is only a theory”, as George W. Bush recently suggested (13 August, p 4), it might be a good idea to add a further label with a definition of “theory”. The Shorter Oxford Dictionary gives “a hypothesis that has been confirmed or established by observation or experiment and is accepted as accounting for known facts”.
Come again, earlier?
Feedback mentions investing in the future to encourage time travellers to pay you a visit (30 July). The week before that piece will be out, a time traveller came (or is that “is coming”?) to visit me from the future to tell me not to read the article yet to be printed, because I would be wasting my money the week after publication when I had put the $1 down as an investment.
The future government has, apparently, taxed the recent past (my distant future), with a retrospective future tax that will mean the time travellers’ fund could not afford to repay my investment in the future.
Councils of hares
I have never heard the term “council of hares” that appears to have sprung unbidden into Grant Hutchison’s mind (Feedback, 6 August). But I have heard of a “rooks’ parliament”, in which a number of rooks settle on open ground and rather than feeding just sit and exchange “caws”.
From Graham Turner
The reason for Hutchison’s surprise may be that both he and the author of the one website he found have misremembered the real term, which is “parliament of hares” or “hares’ parliament”.
Dunedin, New Zealand
For the record
鈥� We misspelled hypnotherapist Charles Montagu’s name (6 August, p 34). Sorry.
鈥� In a story on Huntington’s disease (13 August, p 10), we said that it affects 1 in 100,000 people; the true figure is nearer 1 in 10,000.
Depression's upside
It is hard to argue with Peter Kramer’s opinion that depression is pathological (16 July, p 48). I was, however, surprised and disappointed by his answer to your question about possible evolutionary advantages, and his implication that if there were benefits to depression, everyone would be depressed.
Apart from the obvious objection 鈥� there are benefits to being tall, intelligent, athletic and good-looking, but not everybody has all those traits 鈥� this glib response shuts off potentially useful lines of explanation and research. Kramer himself mentions the sexual attractiveness of the depressed person, so perhaps sexual selection is a factor in the continued existence of depression. Alternatively or additionally, perhaps depression is comparable to, say, sickle-cell disease, in which a trait inherited from one parent confers an advantage but the same trait from both parents gives you a debilitating disease.
It has often been suggested that depressed people make more realistic assessments of themselves and their situation than non-depressed people. Maybe insight is the evolutionary advantage conferred by the non-pathological version of the tendency to depression.
Kramer wants to regard depression as being like cancer and AIDS. Surely obesity is a more apt comparison.
I'm on the phone
We have to concentrate significantly harder to extract information from a telephone conversation than a face-to-face, so it should be no surprise that drivers are distracted as a result (30 July, p 15). Many studies have shown that a significant proportion of communication in a conversation is non-verbal: some of these studies are mentioned in your feature on lying in the same issue (p 28). Gestures and facial expressions contribute to the flow of information in a conversation.
Anyone using a phone is missing part of the message. Simple observation shows that in the street, on trains or wherever else people are on mobile phones, their concentration is utterly devoted to the phone conversation to the exclusion of all else. We use body language all the time without thinking, even when speaking on the telephone.
Braving the ice
The photograph you show of a Greenland glacier is not the Kangerdlugssuaq glacier mentioned in the accompanying story (July 30, p 4). No captain in their right mind would risk a vessel on the almost 30-kilometre voyage up the fjord to the Kangerdlugssuaq’s snout, even in the rare years when this would be possible.
A rate of advance of 1.6 metres per day for this glacier is not surprising, nor is the supposition that “the glacier is speeding up because melting ice is lubricating the rock beneath”. This is a gigantic glacier fed by the main ice cap and by many tributary glaciers, all of which have innumerable crevasses down which hundreds of streams and small rivers pour huge volumes of water in July and August.
The first aerial photographs of the region date only from the early 1980s, so information on earlier flow rates is sparse. A tripling of the flow rate since 1988 is hardly a formidable statistic, and for how long was it measured even in 1988? Only a trifling number of people, mainly geologists, have visited the snout. Those of us who were there in 1975, 1982 and 1986 can attest to enormous variations in the calving rate throughout the summer as well as in the snow and ice cover of the surrounding mountains.
Who runs the internet?
I applaud Paul Marks’s efforts to explain a complex and intricate diplomatic process, but some errors need to be corrected to give a full picture of the Working Group on Internet Governance (30 July, p 22). WGIG was set up in November 2004 as a result of phase one of the World Summit on the Information Society that took place in Geneva in December 2003. The issue of internet governance had polarised the governments in the negotiations, and consequently the summit gave a mandate to the UN secretary-general to convene a group with the task of preparing a report.
The main objective of the exercise was to facilitate the negotiations at the second phase of the summit in Tunis in November 2005. WGIG was not convened to make any policy decisions. Its core mandate has been to clarify whether the internet is being run according to general principles set out by the summit: for instance, is it “multilateral, transparent and democratic and with the involvement of all stakeholders”?
In the words attributed to me regarding a possible unilateral US action, I tried to convey the opinions held by some who feel uncomfortable with the US’s role. These opinions are to a large extent based on what I personally would consider unfounded fears. They are not my own views.
The group in general has recognised the positive role the US played in the development and deployment of the internet and I would be among the first to acknowledge that US stewardship has been very light, benign and beneficial for the internet. I also recognise the excellent job ICANN is doing in managing the Domain Name System.
No goal for evolution
Why do evolutionary biologists speak of “proto humans”? Evolution is goalless. It produces for-the-moment adaptations; it is blind to the future. It cannot produce a proto-anything.
To say that monkeys exhibit proto-human traits (23 July, p 17) such as a degree of empathy is a huge error. Monkeys were never on their way to becoming humans, since evolution never had us, or any other species, as a goal.
Lighting the way
I agree with Roy Milnes that we should be promoting LEDs for use as daytime running lights on road vehicles (6 August, p 38). My recommendation, however, is for lights that are bright enough to be noticed at long range in the daytime. My own research into daytime running lights, done for the Australian National Roads and Motorists’ Association, found that dedicated DRLs could be far more effective and energy-efficient than low-beam headlights.
Glare is not a problem during the daytime with white DRLs at 1200 candelas, which is the brightness recommended by an international expert committee in the early 1990s. But this could be excessive at dusk or dawn, so I favour the use of light sensors to automatically switch from DRLs to headlights at these times.
Evidence for the claim that DRLs on cars will mask vulnerable road users such as pedestrians and cyclists is tenuous, and research findings are mixed. Very few pedestrians, unless drunk, step into the path of an approaching car at night, because the headlights give a clear message that cars are travelling towards them. Well-designed DRLs have the same effect during the daytime. Interested readers will find more at .
How kind a cut?
I think that there are other factors behind the finding that foreskin removal is linked to reduced HIV infection (6 August, p 5). Some people who have had their foreskin removed complain of decreased sexual drive. Perhaps circumcised men have a lower rate of HIV because they are having less sex.
The editor replies:
鈥� Bertran Auvert reports that his study found exactly the reverse: circumcised men reported 18 per cent more sexual contacts than those uncircumcised.
Woodland whiffs
Lovers of forest air might reflect that it may not be entirely health-giving (6 August, p 44). It is replete with terpenes. Certain terpenes, notably the d-limonene responsible for the odour of lemon, cause cancer when fed to animals. This particular response is species-specific and not predictive of cancer in humans, so there is no need to eschew lemons and oranges.
Yet very few terpenes have been tested. Experience suggests that roughly half will come up positive in the standard tests. Either the tests are poor predictors of carcinogenicity in humans, or forest air is no more healthful than ordinary air.
I would like to think that the former is true, and will continue to enjoy the cool of the woods.
Cooler fridges
The design of refrigeration cabinets and the siting of the fridge will have a far more dramatic effect on energy use than the proposal to fit them with cycle counters that you report (30 July, p 24). Fridges are already on the market that draw as little as 19 watts, compared with the usual 100 watts or more.
Domestic fridges in general have a very poor power factor without even considering the real baddies: defrost elements, which draw power when the compressor is not running.