Letters archive

In your article on faces, there was a confounding variable in the reported experiment: smiling (14 February, p 28) . Our brains seem to be hard-wired to interpret smiling positively. Nearly all of your data can be explained by it, yet the experiment does not control for smiles. Only the paired female images gave positive …

The Chagos Conservation Trust (CCT) does not have a "plan" as described by Fred Pearce (21 February, p 10) . The trust will publish a booklet next month on the importance of protecting the environment of the Chagos archipelago, supported by a second scientific document. These documents will show that your title and theme are …

Amanda Gefter, telling us how to detect religious propaganda, writes: "When evolution is described as a 'blind, random, undirected process', be warned. While genetic mutations may be random, natural selection is not," (28 February, p 23) . Of course she is right about natural selection, but might not the writers she complains of have been …

While managing a hostel for the chronically mentally ill, I realised that a deteriorating sleep pattern was the harbinger of illness in a resident, as discussed in Emma Young's article (21 February, p 34) . One year, I was outraged when a consultant psychiatrist prescribed electroconvulsive therapy for an anxious, but otherwise intelligent and gentle, …

Jo Marchant's review of two new books, which rightly highlight Islamic intellectual development from the 7th century onwards, states: "caliphs who... sponsored the translation of scientific texts from lands they had conquered" (21 February, p 46) . Many of these texts would have come from the Byzantines, the inheritors of Greece and Rome. Some credit …

Peter Aldhous writes that type 2 diabetes can be rapidly brought under control by inserting a sleeve into the small intestine, which alters the hormone and nervous signalling from the duodenum (31 January, p 18) . From observing my own diabetes over a period of 16 years I have concluded that it is a signalling …

Stephen Strauss is right when he says that terms like "blueprint" and "book of life" are poor metaphors for the way that DNA functions (21 February, p 22) . I think that a gene works more like a knitting pattern. Both contain instructions which, if followed correctly, result in the assembly of a structure that …

Susie Orbach gave us a rather pained and regretful summary of the modern technology of bodily improvement and augmentation (7 February, p 28) . She stated the obvious facts that plastic surgery, the makeover industry and all the rest concentrate on people's secondary sexual characteristics and their visible indicators of youth and health – and …

• The Crab nebula is in the constellation of Taurus not, as we stated, Orion (7 March, p 14) . • The materials used to print 3D images of bones are tricalcium phosphate and poly(lactic-co-glycolic acid), not tri-calcium triphosphate and polylactic acid (7 March, p 13) . • In "Surviving in a warmer world" (28 …