Letters archive

Olive Heffernan says the idea of towing icebergs to Cape Town in South Africa is dubious and the city must consider alternatives to meet its future water requirements, including possible desalination of seawater ( 19 May, p 20 ). In fact, Cape Town is actively involved in a number of desalination projects, with the focus …

Can we bring it back please because it's been missing for a long, long time? Helen Mahoney responds to a report that the gene that led to the boom in human intelligence has been found ( 9 June, p 6 )

Chris Baraniuk says that a machine learning system can now examine photos and detect fakes ( 26 May, p 10 ). It shouldn't be too long, then, before someone invents an algorithm that trains itself to repeatedly tweak a false image to avoid detection by the algorithm that spots fakes.

Thank you for Fred Pearce's comment on eco-labelling ( 12 May, p 22 ). Many of us share the concern about "greenwash". Fortunately, there is a simple answer for consumers worldwide. Type 1 ecolabels all operate using independently established standards created for the goods or service in question. Individual standards are scientifically robust and transparent, …

• Cyril Burt was involved in developing the 11-plus school admission test system in England and Wales ( 10 February, p 45 ). • Phnom Penh is to the south-east of Bangkok ( 26 May, p 26 ). • Joseph Banks was a naturalist and funder of James Cook's expeditions ( 26 May, p 45 …

Susan Johnston says cattle fed on pasture "must have a lower carbon footprint" (Letters, 2 June ). In fact, pasture-raised animals emit far more methane than those fed grain, and methane dominates other aspects of their carbon footprint. Weight for weight, it has 105 times the warming impact of carbon dioxide during the 20 years …

Do bowhead whales produce two sounds simultaneously through the manipulation of overtones as practised by throat-singers, John Velonis asks (Letters, 2 June ). I compared sonograms I made of normal singing and throat-singing in humans with one of bowhead whales . In normal singing, all the harmonics rise and fall in unison. In throat-singing, the …

David Grimstead mentions "Forrester's Ferric Food", an early 20th-century tonic which may actually have been good for you, and asks whether it sounds like the leghaemoglobin now used in some veggie burgers (Letters, 26 May ). Well, no (unless Forrester was quietly using tonnes of bean roots rather than pressing fruits as advertised). Legumes are …

New Scientist drops weekly though my letterbox in its own printed plastic bag. You have recently run excellent articles highlighting the problem of recycling this type of plastic ( 19 May, p 25 ). So might you consider delivering in a paper envelope? Bath and North East Somerset Council efficiently recycle any paper we leave …

Robert Craig describes the problems of including practical work in science teaching in England, and expresses concern that pupils are missing out on an important part of their education (Letters, 19 May ). Isaac Newton was brought up on a manor farm where he would have seen carpenters and blacksmiths at work. As a boy …