Think bigger
Your story “Giant leap, tiny rock” reported on the US proposal for a crewed mission to a near-Earth asteroid, between 50 and 100 metres across (26 November, p 52). If it was possible to walk on such a body, it could be circumnavigated in minutes and completely explored in hours. This cannot justify the risks of putting a crew in deep space for more than a year. Small rocks can and should be explored by robots.
We should be focusing on Mars for crewed missions. Using resources already there, such as water and atmospheric gases, and with cargo delivery and return from high Mars orbit by efficient solar-powered ion rockets, such a mission is affordable. The crew would achieve more in the first hours on the surface than all the robotic landers to date.
We can exploit the resources of asteroids and comets later. Over the next 30 years Mars is the only suitable target for human exploration in space.
Salt debate
I found Graham Lawton’s article on dietary salt rather disappointing (3 December, p 46), not because it disagreed with my own point of view, but because it stuck to the establishment line.
It is beyond the scope of this letter to go into the mass of peer-reviewed data, including the very recent paper from Martin O’Donnell and colleagues (), cautioning against population-wide sodium reduction down to the 1500 to 2300 milligram per day danger zone.
Rather than being a “vigorous defender of the status quo”, as Lawton states, the Salt Institute is very interested in a clinical trial and has been the only organisation that has asked the US secretary of health to carry out a large-scale trial on the overall health impact of salt reduction. No questions asked, let the science decide.
From Hedley Brown
The article on salt was welcome and might galvanise the UK’s Food Standards Agency to stop the process of augmenting the weight of meat products by injecting saline into them, among the other unnecessary saltings of products.
Nunthorpe, North Yorkshire, UK
From Luce Gilmore
There is plenty of evidence that a high potassium intake mitigates a high sodium intake. The western, junk-food diet is pernicious, being high in sodium but low in potassium, which sends blood pressure up through the action of the hormone vasopressin and the enzyme renin.
Cambridge, UK
The editor writes:
•The interplay between sodium and potassium is complex. At present there is no public health target for potassium, as increasing intake can exacerbate existing conditions in some people – unlike reducing sodium, which is considered to be universally beneficial.
Friendly nudge
Henry Farrell and Cosma Shalizi question the ethics and effectiveness of “nudging” people into making better choices (5 November, p 28). Such questions are sound and justified. We should worry about whether we are manipulated by government. However, most behavioural economists would argue this does not deny people choice and democratic freedom.
Terminology is tricky. Although “nudge” can sound covert, it is also intended to be friendly. Research has proved people suffer biases and make use of heuristics and shortcuts to make decisions. Whether we recognise them and continue to research them or not, these biases will exist. And with problems such as obesity and diabetes, surely arranging canteen shelves so that healthy items are more prominent and easy to reach is smart and serves people’s real interests.
Although the authors rightly point out that high organ-donation rates are a result of good transplant infrastructure, opt-out schemes are still a crucial part of this success. It is also crucial to be aware of the different streams of consent. Opt-in and opt-out is not a simple dichotomy; there are at least six possible types of consent.
In areas where nudging has been applied, we would guess the majority would like to be “nudged”. For example, in the UK, although 65 per cent of people polled in 2008 were prepared to donate organs, only 25 per cent of the population had registered.
To eat more healthily, to be an organ donor, to save for our pensions – these are things that we want to be doing, yet due to our tendency to value things now rather than later, or lack of time, we find difficult.
If nudging were applied in areas where the majority did not support that action, that would be worrying, especially if people who did not get round to opting-out ended up swaying the social norm.
Held to account
Andrew Powell may be right to say in his letter (3 December, p 39) that many people who work in banking are honest. But when people outside the profession talk of “bankers” they mean those with the power to make decisions about how banking is carried out, and by extension those who were responsible for the recent banking crisis, who are not seen as honest at all.
For example, in any ad break on TV these days you are almost guaranteed to be invited to reclaim for “mis-selling” by these apparently honest banks. And how about loan payment protection insurance? Brilliant! That’s almost as good as repackaging debts and selling them on. What kind of idiot would buy a debt? A very greedy one, I suspect. In this same batch of commercials there will, of course, be at least one of those patronising, optimistic, “powerful” scenarios that would have us believe that a particular bank is beneficent and caring. Are we really that stupid?
Religion vs science?
There is no conflict between science and religion; the only disagreement is whether religion is a subset of psychology or memetics.
From Elizabeth Young
James Whalley (19 November, p 37) is sure that there is a “disconnect” between science and religion. My own, uninformed guess is that scientific hypothesis, poetry writing, prayer and worship, and our responses to music and art all probably involve activity in the same part of the brain. Can a neuroscientist tell us?
London, UK
From Mike Williams
James Whalley writes that religion and science are absolutely at loggerheads, but that depends very much on what one’s religious beliefs are. The notions of Christian fundamentalists are a straw man and easy to knock down, but many Christians interpret the stories in Genesis as allegorical and not literal.
Ballingslöv, Sweden
Rhyme time
I couldn’t resist composing this after the mention of the charmingly misspelled word “hematopoetic” in your story on blood grown in the lab from stem cells (12 November, p 8):
Haematopoiesis
Not just hypo-thesis
I’m cultured, I tell ya
I’ll treat haemophilia
Or fill your arterials
With my dark materials
My stem cells just could
Be the future of blood
From Keith Macpherson
Correspondence invoking Freddie Hg (19 March, p 33) reminded me of a poem I wrote on the family blackboard in our house in Vancouver, Canada, at the tender age of 17. I must have been even geekier then than I am now.
I used an early form of optical storage media: I took a photo of the blackboard before erasing the poem. Great news for the world, or this might have been lost forever:
I know that I’m no Es
I’m only Hf Ge
I was born in Fr
That’s Western Eu
Where I married a Ga named Ru
Her old daddy died out in In
So we had to leave Fr to go Ba
And moved to Cf
That’s Western Am
Where we live in a luxurious Ho
I’m now a U Tc
She’s a Pt No
Our kids both Ar
Now life is B
But it does feel good to be Ir
Houston, Renfrewshire, UK
The editor writes:
•As it’s the festive season, the ban on verse is temporarily lifted. Although a gift, it may be of the hairy home-knit variety.
Grounded chimps
In your interview with anthropologist Fiona Stewart on spending a night in a treetop chimp’s nest (8 October, p 31), she says: “One of the interesting questions is when, in our evolution, did we come down to the ground, and why? When did we make the transition from sleeping in trees to sleeping on the ground?”
Maybe we left the trees to get away from the other chimps and get a decent night’s rest. In all seriousness, one of the many things we and chimps have in common is intertribal warfare. It does seem possible that our descent from the trees could have its roots in a cultural disagreement.
You need a we
The contents page line that promoted your look at fungal pathogens as a possible driver for the evolution of warm-bloodedness (3 December, p 1) needs correcting. It stated: “Us mammals are unusually hot for good reasons”. This is partly because we mammals get hot under the collar when we see bad grammar.
Neutrino hunt
Andrew Martin’s letter asks how, if neutrinos are skipping into other dimensions, they “know” when to reappear in this one (3 December, p 39).
But as long as they skip randomly in and out many times on their journey, there will always be some here to be detected. In fact, their unwillingness to interact with other particles could be understood if they were able to spend most of their time in another dimension.
It's a cracker
Feedback’s recent mention of homeopathy (19 November) brought to mind a seasonal joke. What’s a suitable present for a homeopath? An empty box containing the memory of the chocolates that it once contained.