91É«ÇéƬ

I share Clare Wilson's scepticism of complementary medicine, "superfoods" and magical thinking, but the World 91É«ÇéƬ Organization (WHO) summit on alternative therapies was justified. Two of Western medicine's most important therapies, vaccines and analgesics , were first discovered by traditional healers. We shouldn't pre-emptively reject these treatments, even if most of them lack efficacy ( …

With rivers polluted by sewage, frequent drought amid climate change, associated fish deaths, organic waste and low oxygen levels all adding to the woes facing UK rivers and other water bodies, natural measures to address the worst impacts are surely going to become of increasing importance ( 12 August, p 36 ). The argument for …

Regarding the debate over the start of the Anthropocene Epoch, the era of human influence on planetary systems, perhaps it wasn't to do with geology at all. Before we created technologies that led to the Anthropocene, a change in attitude had to happen. I would pinpoint this as occurring in the 16th century, when white …

The article on how some alien worlds may lack the conditions for the discovery of fire suggests that smelting ores to extract metals is probably a prerequisite for the evolution of advanced societies. Yet it neglects the possibility of enzyme or catalyst-mediated manufacturing. For example, one of the hardest and longest-lasting materials in nature is …

Your story states: "Lab experiments have found that combustion can't fully occur in atmospheres with oxygen levels below about 18 per cent." Under what conditions of temperature and pressure does this hold? We can't assume alien atmospheres will always be at pressures and temperatures similar to Earth's.

Though I enjoyed your recent look at the standard model of particle physics, I was surprised the "How to break the standard model" section didn't mention teleparallel gravity, whose "twistors" may unify the electromagnetic force with that of gravity ( 9 September, p 36 ).

A study suggests fruit flies may prefer to sit on a rotating carousel for pure enjoyment. It could be argued that flying barrel rolls and loops would be more entertaining, if fruit flies like to have fun. Isn't it more likely that the flies choose the carousel for other reasons? For example, it might be …

Annalee Newitz, who has had covid-19, says that US doctors are "leery of prescribing . No one is quite sure why." Perhaps the doctors have prior experience of this antiviral? It seems that it is effective at relieving symptoms and possibly in controlling infectivity, but there have been some reports of the virus rebounding after …

I had never heard of an atlatl, the ancient weapon in your recent story. But Australians may have heard of the rocket base developed at Woomera in South Australia , aptly named after an Aboriginal spear-launching device of the same name. This weapon is possibly of far greater antiquity than the one examined at Kent …

From Letters, 26 August

As the years go by, it is increasingly apparent that nuclear fusion may, one distant day, become a reality, but that it is most unlikely to be a significant player in resolving our immediate climate woes. The root problem, I believe, is that everyone expects every joule of energy we currently consume from fossil fuels …