Not as we know it
Large-scale DNA sequencing will undoubtedly shake up our picture of the tree of life (26 March, p 16). As your article reported, it has already led to the identification of new species and the reclassification of some known ones, and may now have resulted in the discovery of a whole new domain.
Sequencing removes the limitation that previously meant bacterial species were only discovered if they could be cultured in a lab. It is now possible to analyse the DNA of entire bacterial ecosystems, whether from a bucket of seawater, a handful of soil or a sample from the human gut. Such efforts clearly help us understand life on our planet and how it originated.
As all life depends on DNA, this approach does not miss any species, no matter how cryptic their lifestyle. Or does it? What if there is life out there which does not rely on DNA? Our focus in the search for new forms of life might be too narrow, and cause us to miss the most interesting ones.
Admittedly, the probability of alternative chemistries having evolved and survived over billions of years is vanishingly small. But given how little we know about most ecosystems and how tiny and inconspicuous microbes are, we will miss it if all we look for is DNA. And what a discovery it would be.
Empathy in reverse
Redefining cruelty in terms of the more measurable concept of zero empathy, as put forward by Simon Baron-Cohen in his interview with Liz Else (9 April, p 32), raises intriguing possibilities.
An autistic boy who places a plastic bag over his mother’s head so that he does not have to see her eyes, or punches his companion at the same time every day because he has learned that the behaviour-modification scheme applied to him as a result will give him some time in isolation, could clearly be seen as lacking empathy.
As a psychologist who shares Baron-Cohen’s interest in psychopathology and extreme cruelty, I am uneasy about the possibility of the application of this concept to the Nazi persecution of the Jews. Would it not seem more likely that these events were historically determined?
One could surmise that the most extreme acts of cruelty require a high degree of empathy, expressed as its mirror image. Sado-masochistic relationships also depend on the capacity to understand pain and knowingly inflict it to the fullest extent.
Defamation defence
Simon Singh rightly draws attention to proposed reforms to English libel law (2 April, p 26). One of the difficulties for legislators is that legislation can be double-edged, and the law cannot generally distinguish between good and bad claimants.
Imagine a scientist who has been vocal in publicising her findings that a new drug has serious side effects. The manufacturer decides to discredit her by encouraging its staff to post allegations that her research is biased because she is secretly in the pay of a competitor.
In this case, it is the innocent scientist who will be the potential claimant, and she will find that the proposed reforms may make it prohibitively expensive to clear her name, as she will now have to prove that the libel caused her “substantial harm”.
As Singh points out, there are proposals to extend the defence of qualified privilege to cover academic and scientific conferences, but they are too limited. The scientific community should focus more attention on expanding the remit of this exemption, perhaps to cover legitimate academic and scientific publications or comment in general.
Consultation on the proposed new law runs until 10 June. 杏吧原创s should make their voices heard.
Perverse pay-off
Writing on the role of financial incentives to change behaviour (9 April, p 40), Nic Fleming notes that the outcomes are often counter-intuitive.
In the academic year 2004-05 I, along with colleagues, ran a randomised controlled trial evaluating the use of financial incentives to encourage adult learners to attend literacy classes (). We found that adult learners in the classes that received a modest financial incentive attended fewer teaching sessions than learners in classes in the control group, who were not paid.
At that time, government policy encouraged the use of financial incentives to increase attendance at basic literacy classes. Given the evidence from this trial, it is clear that such incentives need careful evaluation before they are introduced.
Capturing costs
Your otherwise informative “Instant expert” article about new technologies for carbon capture (2 April) missed some important numbers.
For instance, how much is each technology likely, when mature, to add to the cost of a unit of electricity? And how does that compare with wind and solar?
If we decide we need to cut emissions by 50 per cent in 10 years, can we rule out building new capture-ready coal-fired plants? Is expensive retrofitting the main option?
The article also mentions capturing with algae to produce biomass, most likely as fuel for transport, but as the carbon emitted from vehicles could not be recaptured this would constitute only a single reuse. For maximal benefit, it would have to provide fuel for reuse at the power plant, and we are a very long way from that being viable.
It all adds up
Michael Brooks mentions the prevalence of 12 and 60 in ancient systems of numbers (26 March, p 43) and ascribes this to the Babylonians having 12 signs of the zodiac and considering 60 to be an auspicious number.
But I understand that it originated somewhere in the ancient Middle East, possibly in the Sumerian city of Ur. 10 wasn’t really a big enough number for traders who required a way of counting trade goods like goats, sacks of grain or jars of wine. So they developed a system that works as follows.
Hold your right hand out, palm facing you and fingers open. Now use your thumb to count off the segments of your fingers. Four fingers, three segments on each, that’s 12 goats. Now use the five digits on your left hand to total up the 12s like an abacus. 5脳12 is 60 goats.
From Robert Rounthwaite
As part of your cover story, Michael Brooks suggests we should base our time divisions on the number of fingers we have. Yet the number of digits we have is arbitrary; surely it would be more logical to measure time in a base unit that is evenly divisible by as many whole numbers as possible.
What if we chose a number that was factorable by 2, 3, 4 and 6, instead of just 2 and 5? Then we could represent fractions like 1/3, 1/4 and 1/6 evenly. As it happens, 12 fits the bill perfectly. In some cases it might be nice to get 5 and 10 as even divisions as well. Hey presto: 60!
Maybe those Babylonians were more than mere numerologists.
Fall City, Washington, US
Curing depression
The cover story on novel ways of treating disorders of the brain (9 April, p 35) stated that “until recently the only treatments available… were drugs or surgery”, and these disorders were implied to include depression. This is a common and damaging misconception.
There are other, well-researched treatments for depression, including cognitive behavioural therapy. , CBT has been shown to be as effective as drugs in many cases. It also has fewer side effects.
Origins of faith
The trinity of theism, non-theism and strong atheism by which Jonathan Lanman classifies religious belief and non-belief (26 March, p 38) seems a good description of affluent western Judaeo-Christian society. But what about the rest of the planet?
What conclusions about the origins of belief or non-belief can be drawn when viewed from the perspective of other societies, particularly those based on Buddhism, Islam and Hinduism?
Warmed by contrails
Cirrus-like cloud (2 April, p 16) that originates as aircraft contrails can be expected to have two effects: trapping heat from the ground, and reflecting solar energy back into space. It would help if the model described evaluated the net global warming effect.
London, UK
The editor writes:
Ulrike Burkhardt, whose results we reported, says her model does include both. She emphasised the trapping effect because it is larger.
Culture in the coop
I personally believe that chickens are not much more intelligent than broccoli, but as my wife keeps chickens and believes they are intelligent I thought she might enjoy the article “How to confuse a newborn chick” (26 March, p 22).
Her immediate response was that the minority of chicks drawn to the impossible Escher-like picture as opposed to a plain cube were clearly the more intelligent group, as they were obviously impressed by the art.
World of windmills
Your article says some free energy harnessed by wind farms will be lost as heat, affecting Earth’s energy balance (2 April, p 8). But isn’t all wind energy eventually converted to heat, whether we catch it or not? If it weren’t for windmills, that heat would be generated in forests, mountain slopes and everywhere else where wind slows down.
The good thing about windmills is they produce power to light up my house before that light is also converted to heat.
For the record
鈥� Luke Premo, who we quoted in our article on the fate of the Neanderthals (9 April, p 11), is at Washington State University.