Editor's pick: Extinction is not forever: revival is perennial
Sandrine Ceurstemont mentions plans to revive the extinct aurochs, a large ancestor of domestic cattle (25 February, p 37).
When I was a child, back in the 1960s, I subscribed to a magazine called Animal Life. In its May 1963 issue, I read (p 13) that German zoologists had, by selectively breeding existing cattle, succeeded “after many years” in . There were photos of a cow and bull.
The zoologists were Lutz Heck, , and his brother Heinz, . The unique features of the resurrected aurochs apparently included improved resistance to disease, especially foot and mouth, and a “wilder” disposition.
After this success the brothers turned their attention to the extinct tarpan horse, and, according to the article, had similar success.
I have since read of other scientists trying to do the same from time to time – most recently the Dutch team mentioned. Shouldn't we be awash with aurochs lookalikes?
Wherever cosmic brains arise, they're a headache
It's interesting to see Sean Carroll using anthropic reasoning to argue that we are not in a universe destined to expand forever (18 February, p 9). Such a universe, he says, would see a proliferation of Boltzmann brains, which would outnumber us. This would make it more likely that a random conscious observer would be one of these random fluctuations than a properly evolved human being – a potentially embarrassing situation for some theories.
It is not enough to argue, as Carroll does, that we are not in such a universe. If Boltzmann brains outnumber “normal” brains, then this is a problem wherever and whenever they are: in our universe trillions of light years distant, or in another corner of the multiverse.
We need to understand exactly what might cause some logically possible universes to exist and not others, or to get a statistical grasp on what would be the case if all logically possible universes exist.
First class post
I'd love to be able to hop to a new world about now
Melinda Ayres to TRAPPIST-1's planets being close enough for life to jump between them (18 March, p 14)
What pattern is hidden in the hidden pattern?
So the promising exploration of “hidden patterns” in boiling water has uncovered conformal symmetry (18 February, p 28). That is, features of the pattern look the same under “conformal transformations” that distort space but, within a small region, leave angles unchanged.
Back in 1915, Emmy Noether published her theorem, which states that every system that is invariant with regard to a group of symmetries satisfies a corresponding conservation law (25 April 2015, p 33). Is there a conservation law that is the consequence of conformal symmetry? Conservation of what?
Time considered as a sequence of snapshots
Anil Ananthaswamy describes Julian Barbour's idea of time as “the universe constantly changing from one snapshot to another” (4 February, p 29). That would retain time as a reality.
I understand Barbour's suggestion as defining time by the small differences between snapshots. Given a collection of detailed snapshots of a system, such that a continuous path can be constructed by placing those with the smallest differences adjacent, we would have a good chance of putting them in an order which we call chronological.
But why should weakly connected parts of the system result in the same order? If I watch an hourglass emptying, snapshots of it can be placed in an order, as can the snapshots of my memory (as a whole, not just of the hourglass), but why should the orders match?
A case for cold dark antigravity antimatter
I have long wondered whether antimatter would have the same effect on the curvature of space as normal matter, and was delighted to see that this is going to be tested in the next couple of years (7 January, p 28). In the unlikely event that it does turn out that antimatter has a negative gravitational mass, I wonder what this would say about dark matter.
Cold dark matter is now central to our understanding of the evolution of the universe. It provides the scaffolding for the aggregation of normal matter and the formation of galaxies and stars. Could there be cold dark antimatter with a negative gravitational mass? Could aggregations of this explain the normal matter voids that seem to be associated with dark energy, invoked to explain the accelerating expansion of the universe? In other words, could dark energy be explained by cold dark antimatter?
The editor writes:
• Such a scenario would work if dark antimatter does not gravitationally attract normal antimatter: normal antimatter gives out light just like matter does, and so would not appear to be a void.
Thinking about what is impossible to think
Your Leader proposing that to advance science we must think about the impossible (4 March, p 5) left me wondering whether what we think is constrained by the physical and biochemical construction of the human brain.
What thoughts, visions or dreams might emanate from a brain made of other materials? What effect may communicating these have?
We know that altering the chemistry of the brain can alter its output, don't we? Perhaps we need to experiment more with other aspects of such thoughts, and probe the nature of thoughts.
Give us this day our carbon-efficient bread
Michael Le Page explains that each loaf of bread represents half a kilo of carbon dioxide (4 March, p 14). But without some context, this does not answer the question of whether an intelligent UK consumer should be buying less bread or something else instead.
Bread is actually very efficient in terms of carbon emissions and land use. About 3.5 million tonnes are sold in the UK each year, which is about 150 grams per person per day and about 11 per cent of our daily food intake, allowing for waste.
As Le Page says, this causes 0.5 per cent of UK carbon emissions. Growing the wheat used takes only about a third of a million hectares.
So we can take a crumb of comfort: bread is a small problem. Meat and dairy are a different kettle of fish.
Maybe what you don't eat makes veg healthy
Should we be eating 10 portions of fruit and veg a day (4 March, p 19)? I am suspicious of this research and the recommendation coming out of it.
The 10 portions would amount to 800 grams in total. That's a lot.
Analysis should be able to tease out the effects of the quantity of fruit eaten versus those associated with varying amounts of meat, fat, carbohydrates and so forth. My gut feeling is that people who eat a lot of fruit and veg benefit partly because they are also likely to eat less meat than average, and probably a lot less fat.
What do brain scans really tell us?
Imagine a study finding that people who report feeling hungry have empty stomachs, followed by the finding that MRI scans of their brains show the “paying attention” part lighting up when you wave a bun in front of them. I don't think this would be widely followed up.
So I don't understand the excitement underlying your article on why some people hate chewing noises (11 February, p 14). All the story appears to say is that MRI scans of people who report feeling angry at certain noises show their brain is responding angrily to these sounds.
In the same issue you interview Daniel Dennett (p 42). If, like him, you do not believe that the mind is a mystical object separate from the brain, then it is not surprising that people's reported experience matches their brain's activity. I believe that our experiences form our brain, and our brain activity forms our experiences, in a complicated dance. What would be interesting is how such an unusual feedback loop arose in the first place.
The editor writes:
• A first step to understanding a newly recognised condition is detecting brain activity associated with it. We are learning that some people have a physiological reaction to chewing sounds that makes their lives very difficult. Finding that their brains for some reason devote more attention to these sounds weakens other hypotheses, such as the condition being caused by a preoccupation with polite behaviour.
Was echolocation once found in all mammals?
I was interested to learn that the dormouse also has echolocation (25 February, p 20). Echolocation is famously well developed in two groups of mammals, the bats and the dolphins and whales. Now it has been found in rodents as well, which are only distantly related to the others.
The conventional belief would be that these were three separate evolutions of the same unusual system. But I wonder whether it could be a hangover from primitive mammals, who all used it before the various orders of mammals separated. And maybe it was lost in most of them when mammals diversified after the extinction of the dinosaurs.
Mammalian predators might have been using the signals to track prey. They would lose it when there was no longer a strong advantage in keeping it. Life in the ocean, in the air or up trees might mean it retained an advantage.
For the record
• Water chlorination helps prevent diseases such as dysentery, cholera and typhoid (11 March, p 32).