Letters archive

You reported on the proposal for a US hypersonic uncrewed aircraft – Lockheed Martin's SR-72 equipped with a Mach-3 busting scramjet with built-in jet engines (9 November, p 4) . It's easy to make an aircraft go faster by putting bigger engines on it. What wasn't mentioned in the article are the real obstacles to …

You wrote about the launch of a pilot scheme offering shopping vouchers to mothers who breastfeed their babies for the first six months (16 November, p 5) . We know that breastfeeding has long-term benefits for the baby, and most mothers in the UK have now heard the "breast is best" message loud and clear. …

• Turn to page 29 to read an interview with Mary Renfrew, the architect of the vouchers-for-breastfeeding study.

The US state of Ohio plans to execute a murderer with an untested combination of drugs (2 November, p 7) . In contrast, you reported a humane method of rendering chickens irreversibly unconscious before slaughter in an altitude chamber in Arkansas (9 November, p 14) . It makes you wonder, is Arkansas more humane with …

I read of the crisis in the US penal system arising from the difficulty of obtaining supplies for lethal injections. Although no advocate of the death penalty, I am appalled by the inability to consider readily available morphine, presumably because of the risk that a criminal might die with a smile. London, UK

Your report on the search for a solution to nuclear waste cited the Australian government's refusal in 1999 to accept foreign nuclear waste (2 November, p 42) . However, we have had several changes of government since, and, as explained in your article, there are now more ways of encapsulating nuclear waste for storage than …

Emma Young dates the oldest known tumour in the human ancestral line – a fibrous dysplastic neoplasm in a Neanderthal rib bone – to 120,000 years ago (9 November, p 36) . There is, however, evidence for a much older human tumour. In 2003, a German group described a meningioma in the Steinheim man ( …

In her look at the prevalence of "modern" diseases in ancient populations, Young included researchers who speculate on the extent of disorders such as autism. I'd like to add my own speculation. It seems possible that those with Asperger's syndrome could have proved crucial to the rise of monastic life in earlier eras. Such religious …

David Whitebread and Sue Bingham's article on the school starting age in England was both interesting and concerning (16 November, p 28) . I suspect I am not alone in thinking that it warrants a full exploration of the research and discussion of practical measures that parents of young children in this country can take …

In Jonathon Keats's review of Play, Playfulness, Creativity and Innovation by Patrick Bateson and Paul Martin (7 September, p 44) , he mentions a 2006 study involving 10 and 11-year-old children in a play-based art class, whose originality, fluency and flexibility increased compared with those in a control group. Apparently in Finland, children do nothing …

Geoff Stanley writes in his letter that "superposition of quantum states is only determined by observation... (and this may be the) ultimate example of top-down causation" (12 October, p 31) . This is offered as an example of the macroscopic world impinging on the microscopic. This would be true only if the "decision" to observe …

Letter writer Jörg Michael says it is "widely accepted" that people who come into large sums of money lose it all within a few years. He cites lottery winners as a model for bad decision-making causing poverty (26 October, p 33) . This wrong conclusion derives from choosing an inappropriate sample population. Lottery winners are …

Chris Rogers writes to explain that he, as an atheist, squares moral obligation with a wholly materialistic universe by ethics, compassion and self-respect (9 November, p 31) . This led me to wonder how atheists square ethics, compassion and self-respect with a wholly materialist universe. Now I'm concerned that I may be attempting to square …

Your article on a slowdown in the increase in global emissions of greenhouse gases cites energy efficiency as a key reason (9 November, p 6) . It lists fuel savings in factories, more fuel-efficient trucks and the growing adoption of low-energy light bulbs as examples. Sweeping away unnecessary building regulations could help further, such as …

You report that parents can now choose their baby's traits by selecting eggs or sperm with certain DNA sequences (12 October, p 6) . It will not be long before gold medals will be won at the Olympics by competitors who have body features suspiciously well suited to their sport. The ancient games lasted more …

Feedback asks: "As for Arctic melting being beneficial... to whom?" (2 November) . Well come on, surely 'tis plain and obvious. Without all that inconvenient ice in the way, cable-laying ships can put in place a direct optical link along the great circle between New York and Tokyo, shaving precious microseconds off arbitrage deals on …