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It's great to see another scientist publicly backing what the BUAV has long been calling for: a full scientific analysis on the efficacy of animal experiments in medical research (16 February, p 20) . Animal research falls well short of its oft-stated achievements when systematic, rigorous scientific analysis of the actual evidence-based efficacy is applied, …

Patrick Young claims that "Any fool can get an arts or business degree if they attend occasionally" (23 February, p 20) . I graduated with honours in chemistry, but I took a wide variety of classes, not only from the required maths and computer programming courses but ancient Greek law, Celtic myths, musical theory, criminology …

Those theorising about the possibility of time travel (9 February, p 32) should have a quick chat with those theorising time doesn't exist (19 January, p 26) , who appear to agree with the old mystic philosophers in questioning the ontological status of any time but the present. After all, spending a lot of effort …

• The reference for the paper proposing that computer operating systems should save memory to disc (23 February, p 23) should have been DOI: 10.1016/j.diin.2008.02.001 . • It was Richard Moon who appeared in Oliver at Turvey Village Hall in Bedfordshire, UK – Feedback somehow changed his name to "Wood" (1 March) .

Mark Anderson mentions particle or droplet collision in a fluid in motion or shear as something only recently understood (26 January, p 44) . It was discussed widely more than 100 years ago – in the context of sewage treatment. Marian Smoluchowski's work on colloid coagulation is referred to in water treatment and colloid science …

I was disappointed that Allen Counter feels Matthew Henson "had never received any credit for reaching" the North Pole with Robert Peary (2 February, p 44) . They did so on 6 April, 1909 – not 1906 as Counter states. The expedition was unfortunately mired in controversy at the time, due to the fraudulent claims …

Allen Counter really cannot be allowed to get away with the claim that the language of the Saramacca in Suriname can be understood by inhabitants of Ghana (2 February, p 44) . It is reminiscent of wild statements by travellers in antiquity – such as the supposed ability, 500 years ago, of Irish sailors to …

By asking only his overweight patients about their diet and lifestyle, Gregory Wlodarski has done only half an experiment: he's forgotten his control group (1 March, p 25) . To draw conclusions about the effects of diet and lifestyle on weight, he needs to ask the same questions of his slimmer patients too.

When I wrote that animals' great feats of memory make them resemble autistic savants (23 February, p 8) I was not implying that they were abnormal. My hypothesis is that the Clark's nutcracker and an autistic savant may use similar neurological mechanisms for storing and retrieving pictures of things they have seen in the past. …

Your editorial on modern barbarity (23 February, p 3) and the interview with torture researcher Darius Rejali (p 44) gave only the briefest mention of the unreliability of information obtained using torture. Many people will incriminate innocent friends and relations or confess to crimes they have never committed under torture. So any information obtained is …

Your piece about the ultrasound study of the "G spot" (23 February, p 6) failed to mention many of the scientific problems. First, the authors' definition in their paper of vaginal orgasm as "the orgasm experienced after direct stimulation of the anterior vaginal wall by penetration, without concomitant stimulation of the external clitoris" is technical …

I understand the position of a mother on autism treatment for her son (23 February, p 21) . As an individual with Asperger's syndrome, I have experienced the blessing of a greater intellect and the curse of lacking the more innate social functions. I have experienced misunderstanding and prejudice, but understanding and acceptance from others. …

Perhaps some monkeys prefer silence (23 February, p 29) because music or any noise hinders their ability to listen out for danger. It's not as if they have leisure time in the wild. Being able to appreciate music or indeed any art form may depend on being large, quick or socially organised enough to lead …