The epidemic of myopia raises many questions (1)
The prospect that half the world will have myopia by 2050 might be good news for opticians, but is alarming for the rest of us. The fact that encouraging children to spend more time outdoors helps avoid myopia adds to the list of benefits of doing so, reinforcing the need not to shackle them to the house (16 November, p 40).
There is also evidence that sending children to formal school too early in life results in worse academic outcomes. Countries like Sweden and Estonia don’t start formal school until around the age of 7 while the UK and many others start at 4 or 5. Given children may spend more time inside at school, I wonder if there is a correlation with early-onset myopia.
Another possible factor is that more parents need to work, so more preschoolers are in nursery where the logistics make it harder to allow them much time outdoors.
The epidemic of myopia raises many questions (2)
I favour the idea, one of several raised, that exposure to wide open space outdoors is what reduces myopia rates in children, rather than light exposure. Indoors the eye can only look as far as the walls, while outdoors it needs to deal with vistas of hundreds of metres, if not kilometres. Without this, is it surprising eyes become adapted to seeing close up at the expense of being able to see what is far away?
Was this research really necessary?
Missing from the item about experiments in which researchers used monkeys to predict US election outcomes was the fact that they strapped them into restraint chairs for hours. Those who defend animal experiments claim that animals are only used for important research questions and when there is no alternative, but what was described is case-in-point that those words are meaningless platitudes (2 November, p 48).
Mars colonists could just head for the desert instead
I was glad to read Kelly and Zack Weinersmith’s debunking of Elon Musk’s idea of million-strong colonies on Mars. If people insist on living in hostile places either in domes or underground, the world has numerous deserts where they could establish themselves, with any problems concerning temperature, pressure, radiation or communication with the rest of us easily solved. The great urge to leave Earth and found colonies elsewhere is simply a manifestation of denial of the monstrous problems we shall all need to face here in the near future (16 November, p 48).
Early humans probably didn't need baby slings (1)
Your look at possible botanical craftwork pre-dating the Stone Age mentioned baby slings as a possible example. However, furry mothers don’t need them: their babies have something to cling to. When did humans lose their fur? I suspect a lot of other botanical craft came before baby slings (9 November, p 32).
Early humans probably didn't need baby slings (2)
If anyone still feels that tool use is what turned our animal ancestors into our human ancestors, may I suggest that the dividing line was when the first hominin used a leaf as toilet paper, though I doubt that any evidence survives.
For the real facts, look to the philosophers
One reader suggested a remedy to the issue of poor fact-checking in popular science books of sticking to the greatest scientist-writers. I contend we should instead turn to the writing of philosophers of the impeccable logic of Bertrand Russell or David Hume, say, who are better able to discern fact from fiction and hyperbole (Letters, 9 November).
Athenian democracy was highly questionable
No one should base ideas of democratic reform on the belief that ancient Athenian “democracy” was an ideal form of government (5 October, p 32).
Athens hardly invented democracy: there were very large polities in Eurasia that show no trace of hierarchy and must have been organised by council and consensus thousands of years before Athens, whose government never involved more than 17 per cent of the population.
Socrates, held to be the wisest man in the world, didn’t think Athens better than any other government. It was plagued by factions, demagogues, threats, violence and continual attempts to get opponents exiled or put to death. It ordered the massacre of two cities because they withdrew from an alliance. It decided to invade Syracuse, resulting in the loss of an entire Athenian army, and forced the continuance of war against Sparta, leading to final defeat. It wasn’t a great form of government, rather very irrational and ultimately self-destructive.
Why insects may not make good food for farmed fish
On the idea that insects hold the answer to the dilemma of how best to feed farmed fish, I recently coauthored, along with industry statements, casts doubt on the ability of insects to compete economically with fishmeal made from wild-caught fish (Letters, 16 November).
If insects don’t compete with fishmeal, obviously they won’t solve the serious environmental challenges posed. Even if they did, they score worse than the status quo on some environmental metrics, such as greenhouse gas emissions.
I see nothing worthwhile in free-energy principle
Neuroscience progresses through rigorous empirical measures of neural anatomy, circuitry and chemistry; studies of relationships to behaviour; and comparisons among species. Where is there added value from nebulous and simplistic abstractions such as Markov blankets and the free-energy principle(19 October, p 32)?
These ideas came primarily from philosophy rather than hard science. Their main proponent, Karl Friston, is quoted saying that “…all you can do with the free-energy principle is apply it. You… can’t falsify it, you can’t critique it”. So, essentially it isn’t testable.