Seeds of variety
Well done on highlighting the importance of the many varieties of banana as a food crop. You stated that the fruit is the fourth most important food crop internationally, following wheat, rice and maize (20 April, p 38). This got me thinking about the importance of diversity in our edible plants.
The Food and Agricultural Organization of the United Nations suggests there are 50,000 such species. There are those who suggest the world will need to look beyond the 15 or so species grown in industrial agriculture to ensure diversity and hence stable food supply in the face of threats like disease and climate change.
Having worked among subsistence farmers, I am aware of the hundreds and even thousands of cultivars of each subsistence food crop that may have been bred by such groups. So if there are 50,000 species, there are millions of cultivars, many of which are now rapidly being lost to the world. We need to ensure their survival.
Just add salt
Your feature on uneven global distribution of sea level rise as ice sheets melt highlights a double whammy for northern Europe: greater sea level rise coupled with cooling from a slowing of the Gulf Stream (4 May, p 36).
The cause, an influx of fresh water from Greenland, suggests that an abundant benign material could avert the Gulf Stream problem 鈥� salt. NASA estimates an annual influx of about 200 cubic kilometres of fresh water, which, based on the salinity of sea water, would equate to a deficit of 7 gigatonnes of salt per year.
Adding salt to the water would increase the local albedo, or reflectivity, of the water and also reduce acidification due to carbon dioxide. Moreover, widespread dumping of salt should have less impact on the ocean environment than other proposed geoengineering solutions.
Admittedly, current global salt production is only about 3 per cent of the amount required, but our wider mineral extraction industries already transport considerably more than that per year. I would also be interested to know if larger amounts of salt dumping would increase the transfer of warm water from the tropics to northerly regions.
I wonder if there would be a similar way of influencing ocean currents to reduce warm water transfer to the Antarctic?
Psychiatry today
You recently discussed the future of mental health research (11 May, p 8). We have been telling patients for several decades that we are waiting for biomarkers for mental disorders. We’re still waiting.
In the absence of such major discoveries, it is clinical experience and evidence, as well as growing empirical research, that have advanced our understanding of conditions such as autism spectrum disorder, bipolar disorder and schizophrenia.
This progress is recognised in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). It represents the strongest system available for classifying disorders.
Efforts like the US National Institute of Mental Health’s Research Domain Criteria (RDoC) project, with its emphasis on neurobiology, are vital to the continued progress of our collective understanding of mental disorders. But such an approach cannot serve us in the here and now, and cannot supplant DSM-5.
RDoC is a complementary endeavour to move us forward, which may one day see breakthroughs that will revolutionise our field.
However, every day we are dealing with impairment or tangible suffering, and must respond now. Our patients deserve no less.
The move away from unscientific Freudian-type psychology to unscientific behaviourism-type psychology has been equally disastrous. The US National Institute of Mental Health (NIMH) has taken the first step to remedy the situation, and to properly investigate these serious neurological problems.
Let’s see what is really behind them. That must be the way forward. Thank you, NIMH.
Pain and rain
I have been ambivalent about the pain ray since reading about its potential use as a non-lethal weapon (11 May, p 44). Initially I thought that the ability to incapacitate in a conflict without maiming or killing was a step in the right direction.
However, I recalled that waterboarding was described by some, probably incorrectly, as having no lasting physical effects. I wonder how long it will be before portable “pain rays” enter the interrogation room.
The pain ray’s millimetre-wavelength microwaves are stopped by the water in 0.4 millimetres of skin, but they can penetrate clothing. However, wet clothing might act like skin, and so an easy defence could be to soak your clothes.
High Wycombe, Buckinghamshire, UK
Pet detectives
Feedback highlighted that a gated housing development in Texas was taking swabs from residents’ dogs so that any faeces left on sidewalks could be traced back to their pets (13 April).
Perhaps we should applaud them for realising that a simple pack of swabs makes a cheap deterrent for those who don’t clear up after their dog, given the fear of naming and shaming, with no actual DNA analysis required.
So much hot air
Benjamin Clayton ponders the idea of recovering useful energy from waste sound (4 May, p 34).
So he will be disappointed to learn that the energy generated by the noise from a crowd of about 80,000 people at an international football match at Wembley stadium in London is sufficient to cook only a couple of eggs.
Bee careful
The weight of peer-reviewed scientific evidence does indeed suggest that field-relevant exposure to neonicotinoid pesticides can have adverse effects on bees (4 May, p 6). But whether the EU moratorium on the use of these chemicals will benefit bees depends on what alternative pest control is used.
Bees are exposed to multiple pesticides when foraging, so the risk assessment for pesticides should take account of this, as well as potential sub-lethal behavioural effects and longer-term impacts.
Each year, insects provide essential pollination worth at least 拢440 million to UK agriculture. Pesticides are a crucial tool for achieving high levels of crop production. Both have clear benefits. We need to ensure that pesticides are used in ways that minimise harm to pollinating insects.
Reality check
I must question David Hobday’s explanation of the illusion of self (27 April, p 35), with his example of Alice, who “knows enough to live a healthy, happy life, and expects to die and be reduced to ash. She has no beliefs.”
Alice may think that she exists without beliefs, but this is in itself a symptom of cognitive bias. She has simply elevated her beliefs to the point where she sees them as facts. For example, Alice believes that the world she perceives via her senses is real.
All art
In response to Nick Craddock’s article hoping that psychiatry gets its Higgs boson moment (27 April, p 30), Jeremy Holmes suggested that the discipline “is inherently a marriage of art and science” (11 May, p 31). I half agree: it is art.
Strange thoughts
Douglas Hofstadter and Emmanuel Sander speculate on the pervading nature of analogy in our thought processes, “from throwaway remarks to deep scientific and artistic insights” (4 May, p 30).
I’d point them to a statement sometimes attributed to the German artist Paul Klee: “Art is making the strange familiar and the familiar strange”.
In their emphasis on the importance of analogical thinking in making the strange familiar, of bringing order out of chaos, Hofstadter and Sander underplay its importance in making the familiar strange 鈥� which is an important part of discovering, inventing and finding new and surprising solutions.
400 and rising
The news that atmospheric carbon dioxide levels have reached 400 parts per million is depressing, but no surprise (18 May, p 5). There has been precious little serious effort to address the problem.
Even if net greenhouse gas emissions from human activity somehow became neutral 鈥� through carbon capture and storage, say 鈥� the genie may still be out of the bottle with regard to climate change. There is a time lag of decades between changes in gas levels and temperature changes.
For the record
鈥� Ei! The look at a common origin for seven families of Eurasian languages (11 May, p 10) included a map showing Estonia in the Indo-European family. In fact it is part of the Uralic family.
鈥� In our review of Frank Zelko’s book on the rise of Greenpeace (27 April, p 50), Fred Pearce said the group “began in the US”. In fact, Greenpeace was founded in Vancouver, Canada.
鈥� A bleak future was reported for the painted turtle amid rising temperatures (11 May, p 16). Researcher Rory Telemeco has asked us to clarify that the model used in his research predicted the extinction of one local population on the Mississippi river, rather than the species as a whole.