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• We quoted Steen Stender as saying that Denmark has seen a 20 per cent fall in deaths from heart disease since the 2003 ban on trans-fats (6 January, p 13). He clarifies that there was a 20 per cent fall between 2000 and 2005.

In his discussion of free will, John Searle makes a classic error in attributing purpose to evolution (13 January, p 48). He argues that if we live in an entirely deterministic world, why would evolution have endowed us with expensive features such as big brains, since "all decisions are fixed by deterministic neuron processes", and …

The interview with psychiatrist Patrick Lemoine highlighted some intriguing features of the placebo effect, notably the impact of the doctor-patient relationship (16 December 2006, p 42). It would be interesting to know more about the effect of this on drugs trials. Complementary therapies well-regarded by the public notoriously fare badly in clinical trials. The usual …

We read about lizards that "can see all the colours we can see plus ultraviolet" (6 January, p 36). There is a lot of beauty in the colours we see, but the article vastly understates the information available in the spectrum of light if only we could see it. Taking an average digital camera as …

George Monbiot does his argument no favour by trying to slate the Toyota Prius using a quadruply invalid comparison with the most frugal of the range of Peugeot 205s (23/30 December 2006, p 25). The 205 was a "supermini" and the Prius is a saloon. He compares just highway fuel consumptions, ignoring the fact that …

I believe "good science will come" from the Biologic Institute's efforts to find experimental proof of intelligent design, but not in the way that it intends or believes (13 January, p 18). Starting with a premise or hypothesis, one devises experiments that attempt to negate the hypothesis or premise, demonstrating that it does not hold …

The vanadium flow battery has its attractions for electrical energy storage, but it is certainly not the only system that is practical (13 January, p 39). A quite large nickel-cadmium installation with a capacity of about 7 megawatt-hours is still, as far as I am aware, working in Alaska. There are other technologies, too. Japan …

I have just read the very enjoyable "Mind the mistletoe" (23 December 2006, p 42). I was surprised, however, to read in a sidebar that "The 'Malay kiss', which consists of nose rubbing and sniffing is the 'French kiss' among... Maoris". The hongi is a common Maori greeting, but consists of a nose-press, and sometimes …

Roy Sablosky writes to claim that atheism is not itself a belief (13 January, p 19). But, to quote the Oxford English Dictionary, an atheist is "one who denies or disbelieves the existence of a God". The correct term for someone who does not believe in the existence of a god, but does not assert …

John Searle's argument on free will fails to see the elephant in the room. Seeking indeterminism, he looks for it only at the quantum level. This assertion grossly neglects the findings of chaos theory and complexity theory. These have demonstrated, over and over again, that life is full of complex systems that have deterministic rules …

Let us hypothesise that we can build an intelligent autonomous machine – and take an engineering view of the task. In order for the machine to interact with the complex external world we need to provide it with a model of the world using the finite processing power we have available. Newtonian dynamics can do …

It is logically inescapable that free will, as usually defined, is an illusion; yet John Searle thinks it is odd that evolution would produce this illusion when it has no survival value (13 January, p 48). The ability to carry out "what if" mental simulations is clearly an advantage to the higher animals. But this …

It is indeed scandalous that promising anti-cancer agents such as dichloroacetate (DCA) go begging for support simply because they are cheap and unpatentable (20 January, p 3 and p 13). You have done a great service in bringing this information and perspective before the public. However, after you published online your first article on this …

Ed Douglas's thoughtful article was as revealing in what it didn't say about improving design for sustainability as in what it did (6 January, p 31). What seemed to be missing in the enthusiasm for changing the world by design was a recognition that this will get the support only of "virtuous" manufacturers, not the …