Complexity benefit
Like oceanographer Toby Tyrrell, I am not impressed by James Lovelock’s Gaia hypothesis in the form that he presented it: that is, that life engineers more favourable conditions on Earth (26 October, p 30).
However, it is worth noting that life does introduce a new layer of complexity to the planetary system. This creates more potential feedback loops, both positive and negative. More positive feedbacks would tend to create more fluctuation, but the increased number of negative feedbacks should mean that a compensating negative feedback is likely to kick in sooner.
The net effect should be increased low amplitude fluctuation, but suppression of higher amplitude fluctuations.
This effect of increased complexity is hard to confirm empirically on the scale of a planetary system, but the stabilising effect of greater complexity is well established at the ecosystem level.
Leicester, UK
Safety worries
When I read about the new safety features in the proposed nuclear reactors at Hinkley Point in the UK (19 October, p 6), I became increasingly concerned about the absence of these in our existing reactors. The Hinkley plan makes one realise that as yet none of its ancestors has had a proper burial.
London, UK
Population gamble?
Mairi Macleod writes about the reasons for low birth rates in wealthy countries (26 October, p 46), but she misses one possibility. Darwinian selection works over long timescales, not just from one generation to the next. When the next planet-wide crisis occurs 鈥� be it a third world war, a pandemic, supervolcano or climate catastrophe 鈥� the wealthy will be able to ride it out while the poor will die in large numbers.
Those who accumulate wealth at the expense of reduced birth rates are placing a bet that hard times will come, and that in the long run they will be the winners.
Jomtien, Thailand
Population gamble?
Macleod and those whose work she reports seem unaware of the solution to the population paradox as described by British biologist Ronald Fisher in his 1930 book The Genetical Theory of Natural Selection. He wrote: “The various theories which have sought to discover in wealth a cause of infertility, have missed the point that infertility is an important cause of wealth.”
Cambridge, UK
Utopian future
Biologist Steven Rose is right that the relative contributions of genes and environment to IQ variation depend on the population that is studied (26 October, p 28). The more the environment varies, the lower the contribution, proportionately, from genetic programming.
I also share his scepticism that genome-wide association studies will identify genetic differences that contribute to more than a small percentage of the programming effect.
A good socialist would be aiming to achieve a world in which the environment is the same for all. Variance in everything, including IQ and height, would then be reduced to only the genetic component. That way we would know there isn’t much we can do about it.
Buckingham, UK
Real trauma
Your recent article on multiple personality disorder (28 September, p 46) doesn’t reflect the current scientific and clinical knowledge concerning dissociative identity disorders (DID), nor does it accurately describe the outcome for treatment.
The case that was presented can never reflect the complexity of DID and dissociative disorders. There is considerable research showing that this condition is real, and that most memories of trauma are generally accurate.
Recent research also shows that levels of dissociation decrease rather than increase 鈥� as suggested in the article 鈥� during trauma-oriented treatment when following treatment guidelines.
Brussels, Belgium
Too certain
In Steve Fuller’s review of Serving the Reich: The struggle for the soul of physics under Hitlerby Philip Ball, Werner Heisenberg’s failure to develop an atomic bomb for Germany is attributed to the world’s scientific community shutting its doors to the Nazis (12 October, p 48). I propose an alternative explanation: Heisenberg’s arrogance and scientific blindness.
Biographer David Cassidy recalls Heisenberg’s insistence that he was familiar with diffraction theory, only to flunk questions in his . Later, on the basis of erroneous calculations, he wrongly concluded that atomic fission was impracticable.
Whatever the reason for the failure of Nazi Germany’s atomic bomb project, let’s just say thank goodness.
Old Westbury, New York, US
Strange as fiction
Lisa Grossman describes a bouncing universe model that has been kicked around for some time with no theoretical support (26 October, p 10). However, it is reminiscent of the bouncing universe envisaged in James Blish’s collection of science fiction stories Cities in Flight, in which humans manage to survive the collapse and re-expansion to emerge intact in the new universe. Well done Blish.
Cambridge, Massachusetts, US
Offending cycles
In his review of Big Gods: How religion transformed cooperation and conflict by Ara Norenzayan (28 September, p 52), Michael Bond remarks that the author says people don’t steal bicycles in Denmark, even when they are free to use. Unfortunately, bicycle theft is rampant there.
Perhaps Norenzayan was referring to the “town bicycles” available in Copenhagen during the summer, but there is a good reason they don’t get stolen 鈥� they’re not very good.
Some years ago a bank robber tried to escape on one but, typically, the chain fell off and he was arrested.
Hvidovre, Denmark
Lime is not green
Michael Marshall’s look at geoengineering to keep global temperature rises below 2 掳C (12 October, p 10) suggested ocean liming to form carbonates as one option. He probably means quicklime (calcium oxide) which reacts well, if slowly, with carbon dioxide to form calcium carbonate. However, it is made by heating limestone to drive off the same amount of carbon dioxide it can subsequently absorb.
Calcium oxide also reacts vigorously with seawater to form slaked lime (calcium hydroxide). It is poorly soluble and will sink to the seabed, where it will slowly absorb the same amount of carbon dioxide as was released in its manufacture.
Some slaked lime will dissolve and react to form a solution of calcium bicarbonate, but this will slowly decompose to form calcium carbonate once more, and release one of the carbon dioxide molecules back into the seawater.
I fear this will be an energy intensive cycle of futility.
Brongest, Ceredigion, UK
Oil crisis
Jeremy Leggett speaks clearly enough about fossil fuel depletion, but understates its impact (2 November, p 28). The uncontrollable civil strife that will follow will bring the biggest discontinuity in human history.
Sturminster Newton, Dorset, UK
Sleep aid
You note that vasoactive intestinal polypeptide is shown to be connected with the mammalian circadian clock and might help banish jet lag (2 November, p 10). However, much quicker, simpler and capable of oral administration is melatonin. My experience is that within a day it can counter the impact of time shifts of up to 10 hours.
Reading, Berkshire, UK
Sharing caring
The growth of digital communication certainly helps travellers find local people willing to cook them a meal (26 October, p 24). But it has the potential to do so much more.
In a recent report for Friends of the Earth, Julian Agyeman from Tufts University in Medford, Massachusetts, suggested that the growth of a sharing economy disrupts individualistic and materialistic capitalist economies ().
Sharing cars, rooms, power tools, office spaces and more is getting a boost from digital communications. 3D printing and collaborative work in the digital realm offers opportunities for consumers to become manufacturers. And sharing offers opportunities for those on low incomes to access resources that were once out of reach.
A planet of 8 billion people cannot sustain an economic model which requires everybody to own a car, a library of books and a power drill. The sharing economy offers a more resource efficient and equitable path.
York, UK
Economic heat
Noel Hodson proposes the release of $32 trillion retained by “money capture and storage” in tax havens, to avoid social violence (26 October, p 32). Might this not, by analogy with the release of carbon dioxide reserves created by carbon capture and storage, cause overheating?
Great Missenden, Buckinghamshire, UK
Slow rot
In addition to the “fertiliser effect” on vegetation of rising carbon dioxide levels (12 October, p 40), the work of the humble soil microbe should not be ignored.
Plant material grown in higher levels of CO2 is likely to have a higher carbon:nitrogen ratio, which could slow decomposition by soil microorganisms 鈥� more data for climate models.
Westleton, Suffolk, UK
For the record
鈥� We got our dates muddled in our report on Europe’s health divide (2 November, p 6). We should have said that half of new HIV infections in Greece between 2009 and 2011 are estimated to have been self-inflicted to secure monthly benefits of 鈧�700.