For whom the bell tills
While your article on regulation of the oestrogen mimic bisphenol A (23 October, p 26) was in press, Canada declared BPA “toxic”. Under North American Free Trade Agreement rules, affected parties in the US can challenge this ruling on the grounds that it restricts trade within NAFTA. It will be interesting to see how this plays out.
One source of the chemical you did not mention is thermal printing paper, to contain about 1 per cent BPA. The majority of printed till receipts use this, and small amounts of BPA of anyone who handles these. Most reports say the amount absorbed is small; perhaps they haven’t seen fast-food customers using folded receipts as toothpicks.
From Penny Gadd
Writing about possible harmful effects of bisphenol A, David Melzer and Tamara Galloway ask: “What more do regulators need?” They criticise the European Food Standards Agency for not revising the safety level or tolerable daily intake (TDI) of BPA. This invites the question: what is the function of a regulatory authority?
Complex technologies and innovative materials have given us greater health, greater wealth and longer lives. Like most products of human activity, they also carry some risk to people and to the environment. Society has to balance these risks against the benefits of the activity, while taking into account the risks of alternative technologies.
In Europe, this balancing is done by elected representatives establishing regulatory authorities and drafting laws and policy. The regulatory authorities have to implement these, with a strict regard for evidence and for the consequences of regulation.
Melzer and Galloway write that the dose at which BPA acts as a hormone mimic is subject to “intense scientific dispute” and that average exposure to BPA is “thought to be” orders of magnitude lower than the TDI. Regulators are unable to act when faced with such uncertainty.
The combination of scientific study and regulation has served us well so far, and is evolving to meet future needs. Let’s work constructively to keep it like that.
Weston-super-Mare, Somerset, UK
Mutual aid
Thank you for the all-too-brief article on super-evolution among the “50 Ideas” (9 October, p 32). It is clear enough to me that surviving millions of years is about resilient ecosystems, not selfish individuals. Even bacterial mats seem more aware of their community responsibilities than selfish capitalists. Looking at the heterogeneous colonies walking Wall Street, I can only assume that evolution produces a lot more cooperation than competition.
I look forward to more from researchers who are validating these hypotheses; and to the day when we have an evolutionary buzzword, to supplant “the selfish gene”, that speaks of cooperation, community and ecology.
Seconds out
Brian Bowsher, celebrating SI units’ anniversary, states that all bar one “have been defined by universal, natural constants” (30 October, p 29). But one SI base unit, the metre, is defined in terms of light travel based on another SI unit, the second. While the speed of light might be a universal, natural constant, the second is not.
While two units of mass, length or energy levels may be observed and compared directly in a single event, two seconds of time can never be set one against the other: 9 billion periods of radiation in a caesium atom may currently define a second, but how can we know whether any such batch of periods takes as long as another?
Lamarck's legacy
I was fascinated to learn that trauma experienced by mice can affect their offspring through epigenetic transfer (6 November, p 8), but searched the article in vain for one name: Jean-Baptiste Lamarck. Since he died before Darwin published On the Origin of Species, he did not get the chance to adjust his theories about transfer of acquired characteristics.
Now that there are examples of epigenetic transfer, perhaps Lamarck’s historical importance can be recognised. He may not have been completely right but was by no means entirely wrong 鈥� and was probably, via Robert Grant, an influence on Darwin.
Our bipedal origins
For 50 years we were assured that our ancestors became bipedal and naked as a result of living on the savannah. More recently it has been established that they became bipedal before they ever lived on the savannah. Why then did we ever acquire this unique form of locomotion? Your eight-page guide to human origins (6 November) clarified the current official response to that question. It is very simple: “Don’t ask.”
Grid puzzle
You seem to exaggerate the problem of solar power overloading the electricity grid (30 October, p 4). I understand that buildings with solar panels draw power from the grid when they need it but may supply it to the grid if they generate more than they need. I can’t believe it is beyond the wit of experts in the industry to devise a control system which ensures that the grid only receives power from solar panels when it needs it.
Heli go again
The problems outlined in your article on hybrid helicopters (16 October, p 20) have been solved several times during the history of flight. One notable British example was the Fairey Rotodyne, designed in the 1950s by the same company that produced the Swordfish torpedo bomber, used by the Royal Navy in the second world war.
The Rotodyne had two turboprop propeller engines for forward flight, and rotor blades for vertical take-off and landing. The clever part of the design was the way the rotors were turned: high-pressure air bled from the engines’ compressors fed jets at the tips of the blades.
This eliminated the problem of torque, so the Rotodyne had a conventional tailplane rather than a tail rotor. Sadly, although the prototype performed successfully, it fell victim to government spending cuts and never went into production.
Moral brains
Some writers in your section “Science wakes up to morality” (16 October, p 41) clearly feel they are engaged in territorial wars against philosophy and religion.
Several contributors, notably Patricia Churchland, plainly think that neurobiological explanation supersedes all other kinds of inquiry. But would a detailed account of the brain states used in mathematical thought make other inquiry about the meaning of mathematics, and its place in human life, unnecessary?
It seems bizarre to treat the brain, as Churchland does, as an independent agent, alien to the conscious self, generating policies on its own. The point of thus personifying it seems to be to show that it is not under our control. Yet Fiery Cushman writes (p 41) that seeing morality as a property of the mind will give us “a magical power of control over its future”. Magic will be needed here indeed.
Brains are organs 鈥� tools 鈥� which we use for thinking, just as we use our legs for walking. The only agent is the whole person. And, since ethics deals with the hugely complex relations between these whole persons, it will always raise many different kinds of question.
From Chris Wood
Can science really help decide matters of morality, as Peter Singer suggests (16 October, p 42)? It does not seem to be stopping the rush towards climate disaster. Nor has it done much to optimise levels of fishing. Biodiversity is also a disaster area.
If science is impotent in these rather scientific areas, how can we hope it will do much for ethics?
Hohenbrunn, Germany
Nature and nurture
Evelyn Fox Keller’s apparent dismissal of the use of statistical analysis to resolve the nature/nurture debate is too sweeping (18 September, p 28).
Imagine you could take a random sample of embryos and environments from a given community and try out all combinations of genes and environment. Standard regression tests would reveal which has the greater effect.
The key lies in the phrase “given community”. To take a musical analogy, if 10 violinists of similar accomplishment were to play violins ranging from cracked and broken to the finest made, you would conclude it is the violin that matters more. With 10 people off the street all with standard concert instruments you would take a different view.
It is the context that makes the question meaningful.
Fluffy tales
Your article about the healing power of pets (6 November, p 30) reminded me of a visit I made to a Reform synagogue in Boston one Friday evening this summer.
I was most surprised to see that one of the congregants, sitting quietly in the front row next to some children, was a small white terrier. After the service I asked why the dog was there and was told that he was a therapy dog, helping with the children’s learning. It seems dogs have been found to help with social skills and are a comfort to children who have little self-confidence.
Trained therapy dogs have apparently been used in American schools for many years to encourage children to read aloud and also to give friendship and support to those who find it hard to join in socially.
From Geoffrey Clark
Hal Herzog describes a study comparing pet owners and non-pet owners. I wonder where they purchased their non-pets, and are they soft and cuddly?
Douglas, Isle of Man
For the record
鈥� The cyber-security test range in Fareham, Hampshire, UK, is not a Ministry of Defence facility as we mistakenly implied. It was built, is owned and was opened by Northrop Grumman, with defence minister Gerald Howarth MP as its guest of honour (23 October, p 21).