Editor's pick: It's past time for ordinary climate solutions
Adam Vaughan reports measures we could take to reduce greenhouse gas emissions from transport (30 March, p 23). As he says, they will not be enough. That's because one thing is missing: panic. Academics and policy wonks are still talking as if we are facing an ordinary problem, like stagnant productivity. We are facing a crisis, an existential threat. As Greta Thunberg , we must “act as if the house is on fire. Because it is.”
The time for seeking ideas that don't damage economic growth is over. Trade and growth are parts of the problem. We need policies that reduce emissions every year this century.
Travel by road produces three-quarters of transport emissions. It is vital that we instigate a carbon tax, a rapid shift to electric vehicles and more and better public transport.
We should encourage low-traffic neighbourhoods and active travel, such as cycling. The lifestyle that follows will be healthier and happier, as we exercise more and breathe clearer air. What is good for us is what is good for the planet.
First class post 鈥� 20 April 2019
It's not just polar bears breeding with grizzlies: humans also interbred with others
Alice Outwater at Homo sapiens interbreeding relatively recently with Denisovans (6 April, p 9)
Your piece on the school strike gives me hope
I've grown up reading my father's copies of 快猫短视频, and as a student at the University of Texas at Austin, I have been learning about oceanography and the effects of climate change. I was delighted to read about the youth of the world coming together to combat the detrimental actions that have been contributing to global warming (newscientist.com/article/2194067).
The fact that they are taking a stand through the “school strikes for climate” at such a young age should be enough to show how urgent this situation is. Your article has also given me hope for the future: more kids are being educated and are actively helping to preserve our planet. Most elementary schools – especially in the US – don't have a solid curriculum for teaching about global warming, but this is starting to change. There has been a gradual shift in beliefs and behaviour by some parents, who are now doing what they can to help their kids speak out.
As a fellow student, I agree that climate change is very real, and there is an excess of scientific data that show the beginning of the disastrous impact of our past actions. The governments of the world need to act now, before it is too late.
Population replacement may have been different (1)
Colin Barras reports work on the spread of Yamnaya culture from the Eurasian steppes (30 March, p 29). In the UK, the people who built Stonehenge probably left a genetic legacy. show an influx of DNA from 2450 BC, after which Yamnaya DNA varied from 60 to 100 per cent between individuals. By 2100 BC, levels had stabilised to about 5 to 15 per cent Neolithic DNA, and this endured into the Iron Age of 800 BC.
It isn’t possible to draw more certain conclusions, since the relative population sizes are unknown. There is a gap in the data for about 27 generations from 3000 BC to 2450 BC, so we cannot assume a sudden influx.
Neolithic pottery was very similar to other “Beaker” styles. As Barras notes, life was changing before the steppe people arrived. There is very little evidence of conflict in Britain in 2500 BC. The that the newcomers were mostly male is . The effect seen in the DNA can be explained by a large influx of people arriving to meet a smaller initial population.
Population replacement may have been different (2)
I was most pleased to see my field of study – Corded Ware culture – featured on your cover. But the mention of genocide and “Stone Age conquerors” is, to my mind, overstating the evidence.
Migration is no doubt a factor in the changes observed in the third millennium BC in Europe, but that doesn't equal genocide or conquest. Genetic data indeed show a major shift in ancestry for the Beaker cultures; the data also show a resurgence of indigenous genetic material later.
We cannot interpret genetic data without taking into account biases related to geography, selection of areas of historical research foci and archaeological preservation. The interactions between “indigenous” cultures and Yamnaya migrants bear further analysis.
Population replacement may have been different (3)
Some questions sprang to mind about the spread of the livestock herders called the Yamnaya. Where does this name come from? Barras refers to some of the Yamnaya travelling to the Indian subcontinent. Is this perhaps the origin of the Indo-European family of languages?
The editor writes:
鈥� The name is from “Yamnaya Kultura”, a transliteration of the Russian for “pit culture” 鈥� named in modern times after the form of their “kurgan” graves. Many researchers do believe that these people spoke proto-Indo-European and introduced it to India (4 July 2015, p 28).
Ask the goldilocks planet: it doesn't care (1)
I was interested to read about evolution by persistence and its connection to the Gaia hypothesis of a self-regulating planet (23 March, p 34). It got me thinking about a crucial part of the theory.
Gaia doesn't care.
There is a danger that some people reading the article will take comfort in the belief that Gaia will “act” to ameliorate the effects of global warming and return us to a pre-industrial stable state.
This would miss the point that our current problem has arisen because whatever mechanisms exist to maintain an equilibrium have been overloaded.
It is possible, and perhaps it is probable, that Gaia will undergo a number of changes of state to arrive at a new equilibrium that removes the cause of the problem: us.
Ask the goldilocks planet: it doesn't care (2)
Isn't the most remarkable fact about the evolutionary process that, by means of the human brain on this planet, the “universe” is asking questions about its own existence?
Yet another odd reason for removing teeth
Terrance Chapman doesn't know the reason for his mother-in-law's total tooth removal in the 1930s (Letters, 16 March) and Aroha Mahoney says a neighbour's were removed in the 1950s to save her husband money (Letters, 6 April). My father, who suffered the same fate in the early 1900s, explained that this treatment was based on the idea of “” made popular around that time by the surgeons William Hunter and Frank Billings. Various supposedly superfluous parts of the human body such as teeth, tonsils, spleen and testicles were removed as a precaution against a range of ailments including anaemia, arthritis, schizophrenia and bipolar disorder. Having sacrificed only his teeth, he felt that he probably got off lightly.
Could Neanderthals have farmed these rabbits?
You suggest that the absence of infant rabbit bones at Neanderthal sites means that rabbits were hunted individually rather than flushed from burrows (16 March, p 20). It is also possible that rabbits were raised in captivity and harvested only as adults. I am sure that the Neanderthals were smart enough to cotton on to that concept.
Greens with a side of poisonous arsenic
So a species of caterpillar happily dines on arsenic-loaded leaves (16 March, p 20). I recall how a suggestion that microbes could substitute arsenic for phosphorus in their biochemistry (26 April 2008, p 10) caused a mild furore and then rebuttals (28 January 2012, p 6).
Wouldn't such caterpillars be the place to look for the biochemical co-option of arsenic, and even its active elimination, rather than microbes that are unavoidably – at the per-microbe level – washed in the element?
That these caterpillars bioaccumulate may be an indicator that eukaryotes don't have the biochemical flexibility to do more than isolate the stuff, and can't even excrete it.
Size matters for our friends' quantum views
You draw the conclusion that alternative facts are real from a paradox, which arises from a thought experiment about the states of friends of observers of a quantum event (2 March, p 7). This would only be true if we accepted that an unambiguously quantum object such as a single photon can be “an observer” equal in status to, say, a cat, and you quote physicist Renato Renner challenging this.
The formalism employed in analysis of the experiment treats observers, be they photon or cat, in exactly the same way. But this ignores the problem of how the size of an observer contributes to the decoherence of entangled superposition states. This means that a cat can never be observed in a superposition state from the point of view of a friend sitting next to it. The existence of these superposition states is essential to the conclusion that different observers will disagree about a particular fact.
We probably can't smell the presence of one gene
Geoff Convery suggests that cystic fibrosis carriers might recognise each other through olfaction (Letters, 2 March). But cystic fibrosis is caused by a mutation in a single gene. It seems extremely unlikely that one mutated gene among tens of thousands would be detectable by smell.
For the record 鈥� 20 April 2019
鈥� However it may be discovered that functional disorders arise, there is no suggestion that it is through conscious thinking (6 April, p 28).
鈥� The philosopher Daniel Dennett popularised the word “sphexish” to describe rigidly-determined behaviours, but did not coin it (6 April, p 34).