Paws for thought
The interesting discussion in Kate Ravilious’s article on the ecological impact of owning pets appeared to be based on a fundamental misconception about how pet food is produced (24 October, p 46).
The pet food industry makes use of material that is surplus to the requirements of the human food industry. In the UK, these by-products must meet the safety and quality criteria laid down in European legislation. Without us adding value to around 630,000 tonnes of animal by-products annually in the UK, this material might otherwise have to be disposed of via landfill or incineration, which is not very green.
We must not forget the health benefits of pets, either. Children from households with pets have stronger immune systems and take fewer days off school (), and people with pets make fewer visits to the doctor 鈥� 21 per cent less for elderly people (). What large polluting car improves your health and gets you out for a walk every day?
From Corey Watts
The environmental impact of pets is serious and deserves careful attention, but pet ownership also brings benefits. At least one study demonstrates a close correlation between membership of wildlife protection groups and a childhood spent with animal playmates ().
The need for animal companionship runs deep. By all means campaign for environmentally responsible pet care, but let’s also keep their fluffy, ecological pawprints in perspective.
Brunswick West, Victoria, Australia
From Richard Watts
In your article and editorial (24 October, p 5) about the environmental impacts of pets you claim, based on work by Peter Banks and Jessica Bryant in 2007, that dog walking has long-term impacts on bird populations.
What Banks and Bryant’s study actually showed is that dog walking reduces the number and diversity of birds seen for 10 minutes after the dog passes by, but has no long-term effects. In other words, don’t take your dog birdwatching, but you can otherwise walk your dog in woodlands with a clear conscience.
Watson, ACT, Australia
From Perry Bebbington
The article about the ecological footprint of pets completely misunderstands the relationship between humans and cats.
Humans do not have pet cats; cats have human slaves whose only function is to serve the cat, looking after its every need and making sure it has a comfortable life. From this point of view, what needs to be considered is the ecological footprint of a human cat-slave.
Cats should be encouraged to share their slaves rather than having one each. If the number of cat-slaves could be substantially reduced, most of the world’s problems would go away.
Kimberley, Nottinghamshire, UK
Dog trials
The extended online version of your report on drug trials carried out on pet dogs in the US quotes me as expressing some concern about the use of dogs suffering from cancer to test drugs intended for people (newscientist.com/article/dn17969; 17 October, p 7). I would like to make it clear that I do not object to the principle of scientifically relevant data from ethically conducted veterinary trials being used to benefit people, or indeed vice versa, provided due caution is accorded to the inevitable species differences.
However, I would need more information before being satisfied by the Comparative Oncology Trials Consortium’s claim that the interests of the canine patient are the top priority, given that the researchers ultimately want to know whether the drugs work in people, not dogs.
For example, would a particular drug necessarily be chosen for use in a dog with cancer if it was not ultimately intended for human use? How informed is consent? Are the dogs’ guardians being paid 鈥� perhaps via free treatment for their dogs 鈥� and therefore not really acting as free agents?
Only if I could be satisfied that there are sufficient safeguards in place for the dogs, and full transparency, would I consider this proposal ethically sound.
Scientific truths
According to Rory Allen (17 October, p 31), I was right to criticise Hume’s and Dawkins’s arguments against miracles but a misunderstanding of science mars my case (8 August, p 26). However, he attributes to me a view I did not express and do not hold.
He suggests that I assume scientific laws are statements of the form “if A, then B”, and that these represent “universal laws”. This is a misinterpretation of what I said. My case was that if we assume, as Hume suggests, that science pertains to “universal” laws 鈥� so-called “natural laws” 鈥� his and Dawkins’s arguments about the incompatibility of science and miracles are defective. I did not say that we should make that assumption.
I did not claim in my article that scientists typically frame their theories in terms of universal laws of the form “if A, then B”, nor did I claim that they should aspire to do so. Indeed, I have frequently explicitly written against both of these positions (see, for instance, ; ).
There are various forms that scientific theories can and do take. I am against philosophies of science such as that proposed by Popper in terms of which only particular, specified sorts of statements and methods are considered to be “scientific”.
We should be reluctant to stipulate a priori what sorts of statements scientists might make or what might count as evidence for considering them to be acceptable.
Virtopsies
Your report by Paul Marks makes a good case for virtual autopsies, which use 3D imaging of the exterior and CT scans of the interior of the body to create a faithful virtual double for diagnosis (24 October, p 22).
It is a promising tool that could add much information when used in combination with traditional autopsy. There are, however, some limitations to this procedure that mean it cannot be seen as a replacement for traditional autopsies 鈥� notably, in determining natural causes of death, as discussed in a review of the technique by Stephan Bolliger and others last year (). Scans may not show some details that are visible in a traditional autopsy, such as the nutmeg appearance of the liver of someone who suffered from cirrhosis. Also, distortions can arise in the images obtained if there are any metal objects lodged in the body: the fragments from a gunshot injury, for example.
Nuking asteroids
We cannot push asteroids away with nuclear explosions (26 September, p 30).
A nuclear explosion on Earth heats up and vaporises everything around it, producing a powerful shock wave. Space is a vacuum, so there is nothing to vaporise and heat except the bomb casing. All the energy from the nuclear explosion stays as electromagnetic radiation, which doesn’t push.
It may heat up or even vaporise part of the asteroid, though, if it’s close enough.
The editor writes:
鈥� A nuclear bomb detonated above the asteroid will vaporise its surface, thereby changing its momentum and nudging it onto a safer trajectory.
Farming roos
The letter from Calverley Redfearn implies that to increase harvests of kangaroo meat in Australia, the animals would need to be farmed like sheep or cattle (17 October, p 31).
Several million humanely culled kangaroos are harvested across Australia, but only a small proportion of the meat produced is destined for human consumption, the remainder being used as pet food.
Many environmentalists would prefer to see kangaroo populations better managed and harvested, as this could bring to an end the existing industries based on exotic cloven-hoofed animals grazing natural bushland.
DNA database
Emma Riccobena presents something of an under-informed, alarmist take on issues surrounding the UK’s National DNA Database (3 October, p 29). As one of the “experts” to whom she refers, I would be delighted to respond.
Riccobena’s contention that a DNA database would lead to corrupt experts framing celebrities for money applies to any other evidence type, including eyewitness testimony and CCTV, and disregards the excellent work done by scientific experts 鈥� working for the defence, in many cases 鈥� who enforce the rigorous application of science.
One way to prevent the planting of genetic material that has been stolen from a DNA database is a comprehensive national database in which only the profile 鈥� not the genetic material itself 鈥� is stored. The use of new, more advanced profiling tests can future-proof such a database, eliminating the need for tissue retention for future re-sampling. Such profiles do not include information specific to race, appearance or any genetic conditions that could be abused by any hypothetical, future, dystopian government, eliminating many of the privacy concerns such proposals often attract.
Lastly, the trustworthiness of forensic experts of all kinds is one of the hot topics in the UK forensic science community. The Forensic Science Society works to ensure that people giving evidence in our courts are qualified and competent to do so.
For the record
鈥� Our apologies to Jeff Greason for inserting the sentence “Stephen Hawking calls for moon and Mars colonies” into our interview with him. (24 October, p 27). This was the result of an editing glitch. Greason made no such statement to our interviewer.
鈥� The DOI reference in our article reporting the use of paper as a skeleton for growing animal tissue (24 October, p 10) should have read: .
鈥� The Copenhagen summit runs for four days longer than our “Instant expert” article suggested: it closes on 18 December (7 November, p 13).