Letters archive

The US military is developing a face-recognition device that could be accurate from a kilometre away ( 22 February, p 13 ). The idea seems to be to use this on drones, which will presumably act when detecting a person of interest. A separate prize challenge for such a system, from the US National Institute …

Long-distance, drone-mounted face-recognition systems should surely cause consternation. You have previously reported the inherent errors of this technology, particularly when dealing with faces that don't belong to white men ( 17 February 2018, p 5 ). Those tests used still photographs , presumably taken by firmly fixed static cameras that were no more than a …

There are issues with the fad for eating like our ancestors, as James Wong reports ( 22 February, p 24 ). Another potential problem is with gut bacteria. You can try to recreate a 16th-century diet, but how different were the microbiomes of people then? As with any diet, you also need to consider how …

Paul Dorfman and others argue it is dangerous to say nuclear power is necessary to prevent climate change, in part because we can't build enough stations to achieve a carbon-neutral global energy system in time (Letters, 29 February ). I am not convinced we should ignore the idea that nuclear power can help meet our …

• It is in fact hard to overestimate how odd the swan-like aquatic dinosaur Halszkaraptor escuilliei is ( 15 February, p 40 ).

Emma Young's article on facial expressions was very interesting ( 15 February, p 44 ). I was particularly taken with – though not surprised by – the implication that the FBI, other agencies and even commercial operations may be funding, and drawing conclusions from, questionable practices. These include programmes designed to train agents to spot …

Young's discussion of facial expressions was fascinating, not least for reporting research where subjects were asked to match the "right" emotion to images of posed facial expressions. But how good were the posers? I wonder, too, how our reading of facial expressions is affected by the phenomena of "selfie faces" and by what I call …

Why not change the order in which we teach the alphabet to the QWERTY keyboard layout, Linda Phillips asks (Letters, 29 February ). Well, not every language that uses the Latin alphabet uses that keyboard arrangement. As someone who touch-types, I frequently put spellcheckers to the test when visiting customers in France and Germany, where …

The principal benefit of traditional alphabetical order is felt in reference material. Although the corpus of reference texts available and searchable electronically grows ever larger, many of us find that the text we want isn't available, or is very expensive compared with a paper copy. In these cases, the index – and sometimes the body …

Graham Lawton draws attention to some of the subtleties of meeting targets for net-zero carbon emissions ( 8 February, p 24 ). Another arises when a relatively small area – that of a district council, say – sets such a goal. Too often, this means exporting surplus solar electricity during the day to offset usage …