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In your look at the sensory world of plants, Daniel Chamovitz states "there are sounds that it could be advantageous for plants to hear", including vibrations "such as a bee's buzz" (25 August, p 35) . This was graphically illustrated by geologist Iain Stewart in the BBC television series How to Grow a Planet . …

Catherine de Lange's look at the growing influence of smartphones lamented the removal of chance and choice in our lives by technologies like GPS and recommendation services (25 August, p 46) , and went on to commend alternative apps like Serendipitor that can give us back some whimsy. Her comment about how "strangely exhilarating" it …

Further to your article on Neil Armstrong's death (1 September, p 4) , I think of him as a pilot. I don't know if it took an exceptionally skilled pilot to land on the moon or just a capable one. Perhaps it is not politically correct to ask. Media exposure leads many to idolise sports …

I'd like to respond to your report on the creation of a mathematical model that supports my evolutionary psychology theory of the placebo effect (8 September, p 9) . I welcome this development, but it just formalises a logically strong argument I put forward 10 years ago, supported by a wealth of facts. In the …

Further to your review of The Human Quest , which discusses environmental tipping points for Earth (18 August, p 51) , it looks as if we may be too late. We appear to be at the first of these long-anticipated tipping points, as shown by the record decline in Arctic ice cover this year. The …

I was rather concerned by speculation that white dwarf stars could harbour habitable planets simply because these stars emit light at the right wavelengths to sustain photosynthesis (18 August, p 8) . Surely anywhere life evolves it will utilise the dominant wavelengths from the local star. It is not divine providence that has made our …

You report that the IBM supercomputer Watson is aiding medical diagnoses (25 August, p 19) . Why is anyone in the least bit surprised that it is useful? Many people long to be assessed by a computer that will set aside human preconceptions and listen to a full range of symptoms. After the 30 years …

Your mention of pharaoh Akhenaten's possible epilepsy and its suggested link to religious conversion (8 September, p 10) may have a parallel in the biblical story of the Damascene conversion of Saul, who gave up persecuting Christians and became one of their primary advocates after he saw a heavenly light and heard a divine voice. …

Nina Jablonski's article on racism (1 September, p 26) doesn't address the complexity of the issue. Far from having a relentless white-to-black polarity, racism is multidirectional. The Kantian meme she recounts explains very little except one recent expression of one western form of racism.

Further to your look at addiction (8 September, p 36) , the overarching clinical and scientific language on this subject is one of puritanical moralism, with drug use and so on being a sin that leads to death and damnation, which can only be escaped through repentance, reform, rehabilitation and salvation. As a psychiatrist in …

You report on self-trackers who record many aspects of their lives (4 August, p 40) , and I must confess to a similar habit: I have a record of every bath I have had since I was a teenager (I am now 53). Over the same period, I also have a record of every cold …

Your article on possible links between dementia and diabetes argued that a high-sugar, high-fat diet is damaging to the brain by raising insensitivity to insulin (1 September, p 32) . However, type 1 diabetics take insulin to balance carbohydrate and sugar, not to deal with fat and protein. That suggests to me that raised insulin …

It says something about the financial sector's current reputation that, when I misread your headline "The algorithm that runs the world" (11 August, p 32) as "The algorithm that ruins the world", I immediately expected the story to be about automated trading. It wasn't, of course.

• The Feedback story about an "impossible restriction" (8 September) should have been credited to Mike Whittaker.