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Lenny Smith makes a number of important points concerning the consequences of overselling the results from climate models, but he omits an important one (6 December 2008, p 42) . Those who overstate the present capability of climate models risk creating the perception that models can substitute for measurement and so undermine the case for …

One important item was missing from your power-saving suggestions (6 December 2008, p 30) in the article "Life unplugged". Home heating takes a lot of power, especially when it comes to getting fresh air into the house. Could we not virtually eliminate energy use for heating (or cooling) incoming air by using a counter-flow heat …

Alison Motluk makes no mention of the opportunity an early menopause offers to pass on culture, and the great advantage this provides (13 December 2008, p 41) . It is obvious that we are separated from other primates by culture – and by being hugely more successful in evolutionary terms than they. Pregnancy is a …

Scientists and engineers have indeed done an impressive job in realising Moore's law over the years (6 December 2008, p 35) . What a pity that the average PC user has not seen the equivalent leap in "user experience". A combination of operating system bloat, poorly configured and maintained networks, and overzealous virus checkers means …

You speculate on what the Greeks might have achieved had the Romans not supplanted their culture (13 December 2008, p 5) . This rather misunderstands the role of the Romans, who were great admirers of the Greeks and eagerly adopted much of Greek thought and culture. The Romans might not have been particularly original thinkers …

Bernd Brunner is "terrified" by Clare Wilson saying an "intelligent and well-informed" gay man "sometimes" has unsafe sex. He sees this as a contradiction, and believes this kind of behaviour to be unusual (20/27 December 2008, p 18) . If his reasoning were correct, then intelligent, informed people would never smoke, take drugs, drink to …

Marcus du Sautoy opines that we have the innate mathematics skills needed to survive things being thrown at us and gauge enemies' sizes (29 November 2008, p 44) . My dog can compute the trajectory and velocity of an object far better than I can. Does this mean that she is better at mathematics than …

Copernicus may have expelled us in principle from the centre of the universe (15 November 2008, p 32) , but I am reminded of an incident in Spike Milligan's memoirs of the British army: Officer (shouting): "You there, what are you doing over there?" Milligan: "Uh, everybody gotta be somewhere, sir."

• Scud missiles are not intercontinental ballistic missiles: they have a range of only 1000 kilometres and are classed as intermediate-range ballistic missiles (13 December 2008, p 26) .

A life unplugged is an idea close to my heart (6 December 2008, p 30) . Since discovering the Centre for Alternative Technology at Machynlleth in mid-Wales, near my ancestral home of Dolgellau, 28 years ago, I have frequently flirted with the dream. But two flaws have held back a full commitment. As "simple" as …

One thing has been puzzling me about the hybrid cars being rolled out by the car industry (20 September 2008, p 26) : why don't they use Stirling engines to drive the generators? The point is that this would be much cleaner than any internal combustion engine, much more fuel-efficient and perfectly capable of running …

• We reported the European Court of Human Rights ruling that "the UK's national DNA database... must remove more than 800,000 of roughly 4.5 million profiles" (online news, 9 December 2008) . In fact, the judgment applied to England, Wales and Northern Ireland; Scottish law already insisted that DNA samples taken when people are arrested …