Ancient DNA tests must be used on Martian dirt
Laura Spinney’s informative article on the isolation of ancient DNA (aDNA) from soil raises an intriguing consideration. Soil collected by NASA’s Mars Perseverance rover will return to Earth as part of the Mars Sample Return mission, probably some time in the 2030s. I suspect I am not the only person now eagerly awaiting the analysis of these samples for aDNA and the possible answering of one of the oldest questions known to modern humankind (4 January, p 36).
Many possible causes of dip in obesity in US
Weight-loss drugs are probably playing a part in the slight dip in obesity in the US. But like many other parts of the world, the country has seen high inflation during the past few years, which has caused a cost-of-living crisis, raising food and energy prices. The consequence has almost certainly been lower food consumption and possibly less use of vehicles to save money, which would probably affect the rate of obesity (11 January, p 10).
Mars colony doomed after Earth extinction
A colony on Mars will fail as a back-up plan after a catastrophe on Earth. It is hard to see how it could repopulate Earth with a significant number of people. Returning to Earth from space is a logistical nightmare at the best of times and requires functioning landing sites or splashdowns, with rescue by ship or similar (Letters, 28 December 2024).
A Mars colony will be totally dependent on a technologically advanced society on Earth and is doomed without it. As far as I know, colonists aren’t expected to forge their own screwdrivers from Martian material. More broadly, life has thrived here for billions of years without us and will do so long after we become extinct.
Waitress robot was a bit much
When I saw the image of the server robot in a dress, with a feminine chest, I assumed its appearance would be addressed. In particular, the sexist practice of casting obviously female robots in subservient roles. But it wasn’t. I hope the modestly covered chest hides a pair of fembot boob missiles 鈥� she may need them (28 December 2024, p 9).
My cat showed that pets can have theory of mind
Thomas Lewton is left doubting that his dog considers him a being with a mind of his own. I don’t know about that, but my cat Dolcina, who lived 18 years, knew very well that humans have their own point of view on the world (14/21 December 2024, p 66).
Our house is in the country, and Dolcina often stayed outside all day and came home at night. To return, she used the door to the terrace, which was half-obscured by a semi-transparent curtain. Therefore, Dolcina could see us in the lighted room, but we couldn’t see her in the darkness outside and so wouldn’t know to open the door for her.
So the cat would climb along the mosquito net until her head was above the curtain, wait patiently for one of us to see her and stare at her, and jump down, confident that we would now let her in. In short, Dolcina realised that our view of the scenario was different from hers, and operated in such a way that her knowledge of being there waiting could be shared by us: a spontaneous experiment in cats’ capacity for “theory of mind”.
Well-adjusted AIs are in all our interests
Preparing to consider the welfare of synthetic thinking entities is prudent. Remember that HAL, the AI in 2001: A Space Odyssey, only became homicidal because Making sure AIs are happy and well adjusted is in our interest (28 December 2024, p 17).
Your views on how to be an optimist (1)
You report that being an optimist tends to lead to better outcomes, and yet I can’t help thinking that the cause/effect might be the other way around. The initial example about the bee seems to underline that possibility, where a positive experience makes the bee more optimistic. If our brains are working at a fundamentally Bayesian level, their model of the world would be updated with positive or negative outcomes, and so those with more good things going on would naturally become more optimistic (4 January, p 32).
Your views on how to be an optimist (2)
You report that a plausible way to become an optimist is the Best Possible Self exercise, which takes 20 minutes a day for a fortnight and then wears off in another week. As a teacher, I can suggest a better way. As all good teachers below degree level know, the role isn’t primarily about imparting skills or knowledge, but generating an experience of success and sense of achievement, the consequence of which is a feeling of self-worth and the ability to be effective. This is optimism that lasts a lifetime.
Fossil carbon is OK so long as it is kept from the air
On the subject of ensuring the carbon in goods doesn’t come from fossil fuels, what matters is the fate of the goods after use, not where their carbon came from. If you use something made from recycled plastic but then discard it and it turns into methane, you have added to global warming. If it is made from petroleum and afterwards remains intact forever, then you haven’t. And if products made from non-fossil carbon cost more (as they do), it is usually a sign that more resources and energy were used to produce them (4 January, p 22).
Confine all talk of time travel to fiction
Why even discuss “time” travel outside fiction? We have no concept of what “time” is or if it even exists, just measurements of events compared with each other, the decay of atoms, the movement of the stars, etc (14/21 December 2024, p 54).