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To any persistent observer, the intelligence and personality of crows are undeniable – as outlined in Adrian Barnett's review of Gifts of the Crow (2 June, p 49) . While it could be argued that such interpretations are subjective, the growing number of observations of crow behaviour surely carries some scientific weight. As a hang-glider …

The presence of a modified component in messenger RNA (mRNA) – nucleotide base N6-methyladenosine – is an exciting and under-studied area (26 May, p 16) . Your article on the work of Samie Jaffrey's group at Cornell University in New York ( Cell , DOI:10.1016/j.cell.2012.05.003 ) gave the impression that this is a new discovery. …

There may be another explanation for how ichthyosaurs – "dino dolphins" – suffered the bends other than rapid surfacing in the presence of predators (26 May, p 17) . They would dive with one atmosphere of pressure in their lungs and when they surfaced, no matter how fast, they would have only one atmosphere of …

Lasting love and the benefits of rearing progeny through a joint effort have developed over centuries of trial and error, and cannot be boiled down to the simple interactions of a few hormones, as proposed in "Engineering love" (12 May, p 28) . Some 70 years ago, my father lamented that it was too easy …

In your editorial on a possible Greek exit from the eurozone, you wrote: "If the theorists are right, the eurozone was built on quicksand from the start" (26 May, p 3) . The "if" is superfluous and no "theorists" are needed. More interesting, from a scientific point of view, is why no serious scientific study …

Further to Ian Flett's letter on flying fish (19 May, p 32) , in essence, they are very sophisticated flying machines, lacking only an airborne propulsion system. It is generally considered that tree-dwellers capable of true flight went through a stage of gliding, like flying squirrels. Flying fish are already more capable than any arboreal …

The idea that the Yupno tribe of Papua New Guinea regard time as flowing uphill could be unwarranted (2 June, p 14) . When gesturing downriver, they're probably just indicating water (or events) that have passed them (or happened) some time ago: the "past". When pointing upriver, they're probably just indicating water (or events) still …

Your Instant Expert ( 2 June ) on the legacy of Alan Turing did not mention the Pilot ACE (Automatic Computing Engine) which has a strong claim to be regarded as the first high-speed, stored-program, Von Neumann-architecture digital computer. It was based on Turing's original design for a full ACE version and was built at …

The idea of a group coming to a correct or better answer than an individual as a result of our innate argumentative nature has its merits (26 May, p 32) . However, "groupthink" in the real world is often responsible for bizarre outcomes, in particular in politics. Coupled with the suggestion that individual choice is …

You reported Richard Cincotta's research, which shows that autocratic nations with a low median age are unlikely to secure democracy in the wake of revolution, such as the Arab spring (19 May, p 8) . Although birth rates had full coverage, a key contributor to understanding the data for ageing populations must also include survival …

You posed the question of how big an object can be and still show quantum properties (14 April, p 8) . In my experience, it can be at least as big as a sock, as they seem to pop out of existence at random (check the number of odd ones in the sock drawer). I …

• We got our moons in a muddle. In our story on possible liquid oceans on Neptune's satellite Triton we used a picture of Saturn's moon Titan (2 June, p 17) .