Editor's pick: Don't dismiss the power of dreaming
Philip Ball reports scepticism over the claim by a colleague of chemist Dmitri Mendeleev that the periodic table came to him in a dream (2 March, p 34). But there is evidence of the role of the unconscious mind in problem-solving (28 July 2018, p 34). This seems to be linked to the power of sleep to consolidate emerging ideas (24 March 2018, p 32).
The philosopher of science Thomas Kuhn claimed science is structured by “paradigms” that are replaced not by deliberation and interpretation, but by a relatively sudden and unstructured event. He wrote of scientists speaking of the “scales falling from the eyes” or the “lightning flash” that illuminates a previously obscure puzzle.
In Investigation, William Beveridge recounts a number of such descriptions, including the physicist Hermann von Helmholtz reporting: “Happy ideas came unexpectedly without effort, like an inspiration”. All were associated with a period of relaxation, apparently when the unconscious mind had been working on the problem.
First class post 鈥� 06 April 2019
As both Earth and life are rare and precious, it’s time to appreciate our home planet
Fleeting Flo from the news that out of 4000 exoplanets, none may be right for life (30 March, p 14)
Female and male brains and hormones' effects
George Chaplin (Letters, 23 March) and Lawrence Bernstein (Letters, 30 March) note the omission of the role of hormones in my article on male and female brains (2 March, p 28). The focus of the piece was on brain structure and function, but the role of hormones is very much part of the arguments I consider in my book .
I devote a chapter to the changing views on the extent and stability of sex differences that are informing research in cognitive neuroscience and those informing our understanding of the links between hormones and behaviour investigated by psychoneuroendocrinologists. This discipline is undergoing just the kind of rethink that is core to my argument for the need to revisit our answers to the question of whether women's brains are different from men's.
For example, evidence of socially induced plasticity in the levels of the hormone testosterone among fathers who are primary caregivers shows the need to acknowledge how entangled nature is with nurture.
This rethink will include the impacts of cultural expectations, biological factors and a multiplicity of brain-changing life factors. The power and influence of these will vary over time and in different situations.
Such flexibility and variability, both within and between sexes, in all measures of biology and behaviour, has major implications for the extent to which we can invoke evolutionary explanations or make reference to assumed biological or cultural universals in explaining individual differences in human behaviour.
Mixed messages on wood as sustainable fuel (1)
Graham Lawton says wood is a carbon-neutral biofuel so long as trees are replanted (16 March, p 33). But Michael Le Page reports the European Union being sued for making global warming worse by burning wood (9 March, p 9). He notes that wood burning might seem an appealing alternative to fossil fuels, but it produces more carbon dioxide than coal per unit of energy.
Mixed messages on wood as sustainable fuel (2)
Is wood burning good or bad for the climate? The answer is: it depends. Foresters are used to taking a long-term perspective. Good forestry means managing wood harvesting so the forest can continue to provide ecosystem services and maintain its carbon stock in the long term.
Whether or not wood can be considered as a renewable resource for building materials, furniture, paper and indeed renewable energy therefore depends on whether it is the product of good forestry practice.
As a rule of thumb, if producing bioenergy involves intense farming, its eco-balance is probably negative. But if biomass is used as a fuel at the end of its material life cycle, its eco-balance is, in most cases, positive. This means the way to go for wood is: use it first as a material and then, at the end of its life cycle, exploit the wood's fuel value in a clean process, such as gasification.
Other people cut fingers as a mark of defiance
Some peoples cut off fingers in mourning, report Margaret McGovern from Canada (Letters, 23 February) and Ted Webber from New Guinea (Letters, 23 March). When I worked in Papua New Guinea, a young employee walked in with a large bandage on a finger of her left hand. She had cut off the top joint in response to her parents trying to force her to do a thing that she definitely didn't want to do.
Barbaric practices – in 1950s New Zealand
Terrance Chapman says his mother-in-law had her teeth removed in her teens in the 1930s (Letters, 16 March). The practice continued in New Zealand in the 1950s. A neighbour's daughter had her teeth out when I was a child and I was puzzled at anyone voluntarily going through this. She told me it was because the daughter was getting married and having her teeth out would save her husband money.
Speed of climate change and the fate of insects
You report the alarming decline of insects due to habitat loss and climate change (16 February, p 6). The response of insects to the latter is likely to be adaptation by evolution. Creatures with shorter lifespans can adapt faster and displace those who live longer. Those with the shortest lifespans, such as cyanobacteria, are thriving as things are.
The suggests that adaptable, generalist insects will fill niches vacated by declining specialists. Generalist German and common wasps have already reached plague proportions in parts of New Zealand, while specialists such as honeybees have declined.
Specialists appear to be declining in response to the causes of climate change, such as changes in land use, and to pesticides and water pollution. If this is so, they may eventually arise once more in forms that are more tolerant of new conditions.
The writer of this letter has asked that their name be removed from it
Insect decline hidden by automotive design
Alan Wilkinson asks whether biologists should have noticed how windscreens were crushing fewer insects by the mid-1960s (Letters, 9 March). I have seen such a decline, but I put it down to aerodynamic improvements in the cars I drive. Has this been taken into account? I am also a motorcyclist and I haven't noticed a fall in the number of insects deposited on my visor or clothing.
Does it matter what television we watch?
You report that older people's memory may worsen if they watch lots of television (9 March, p 20). Does content matter? My husband and I watch quiz shows such as University Challenge – at which we compete fiercely – documentaries and comedy panel shows. Will we end up drooling?
The climate cost of cheese in context (1)
You illustrate the carbon footprint of a kilogram of cheese and other foods (16 February, p 30). It would be more useful to see the carbon footprint per kg of dry mass.
I estimate that milk (90 per cent water) has an impact of 12.5 kg of CO2 equivalent per kg of biomass; cheddar cheese (37 per cent water) an impact of 13.8; chicken (65 per cent water) 14.2 and pork (65 per cent water) 17.8.
The climate cost of cheese in context (2)
You make a persuasive case for looking at carbon dioxide emission per calorie. I would like to see a chart that shows this.
Pass the sourdough starter on the left side
Having yeast make cannabinoids sounds useful to medicine (2 March, p 9). I cannot imagine, though, that they will stay cloistered in the lab for long. They could be transferred as easily as a sourdough starter, allowing interesting wine, beer and bread to be made.
Not on me 'ead, mate: a case for reforming soccer'
You report that association football players are working harder and getting injured more often (2 March, p 16). These health and injury issues are common to many professional sports.
One of the worst problems in association football, though, is that players are expected to be able to head the ball – as are children in sports lessons.
This has been shown to cause irreversible brain damage just as blows to the head in boxing do. The sooner the rules of football are changed to treat heading as a foul, in the same way that a handball is, the better.
What if an illusionary entity has an illusion?
Willem Windig is surely right when he says that “illusion” is a word used far too freely (Letters, 9 March). The one view we cannot take of consciousness and mind is that they are an illusion. If we do then, logically, that view must itself be an illusion, since it is part of our illusory consciousness.
For the record 鈥� 06 April 2019
鈥� Inconstant wind: storm Idai crossed Mozambique into Malawi and went back out to sea. Then, upgraded to a cyclone, it crossed Mozambique to Zimbabwe (23 March, p 6).
鈥� They’ve really made the grade: it is the US space agency NASA that has a training cohort of whom half are women (23 March, p 24).
鈥� For tropical use: we have posted a corrected map showing the number of minutes’ sun you need to get your daily vitamin D at different latitudes at bit.ly/NS-sun (16 March, p 28).
